JavaWeb-09(HttpServletRequest对象&会话管理之Cookie)

时间：2015-04-01 11:30:06 阅读：238 评论：0 收藏：0 [点我收藏+]

JAVAWEB-09：HttpServletRequest对象&会话管理之Cookie

HttpServletRequest

一、HttpServletRequest对象：

代表客户端的请求，当客户端通过HTTP协议访问服务器时，HTTP请求头中的所有信息都封装在这个对象中，开发人员通过这个对象的方法，可以获得客户这些信息。

二、request常用方法

1、获得客户机信息

getRequestURL方法返回客户端发出请求时的完整URL。

getRequestURI方法返回请求行中的资源名部分。

getQueryString 方法返回请求行中的参数部分。

getRemoteAddr方法返回发出请求的客户机的IP地址

getRemoteHost方法返回发出请求的客户机的完整主机名

getRemotePort方法返回客户机所使用的网络端口号

getLocalAddr方法返回WEB服务器的IP地址。

getLocalName方法返回WEB服务器的主机名

getMethod得到客户机请求方式

实验：/day0900httpServletRequest工程工程架构如下：

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配置文件web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
    xmlns="http://java.sun.com/xml/ns/javaee" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <display-name></display-name>
  <servlet>
    <servlet-name>ServletRequest1</servlet-name>
    <servlet-class>com.heima.request.ServletRequest1</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletRequest2</servlet-name>
    <servlet-class>com.heima.request.ServletRequest2</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletReqeust3</servlet-name>
    <servlet-class>com.heima.request.ServletReqeust3</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletReqeust4</servlet-name>
    <servlet-class>com.heima.request.ServletReqeust4</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletReqeust5</servlet-name>
    <servlet-class>com.heima.request.ServletReqeust5</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletRequest6</servlet-name>
    <servlet-class>com.heima.request.ServletRequest6</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletRequest7</servlet-name>
    <servlet-class>com.heima.request.ServletRequest7</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletRequest8</servlet-name>
    <servlet-class>com.heima.request.ServletRequest8</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletRequest9</servlet-name>
    <servlet-class>com.heima.request.ServletRequest9</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>ServletRequest1</servlet-name>
    <url-pattern>/servlet/ServletRequest1</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletRequest2</servlet-name>
    <url-pattern>/servlet/ServletRequest2</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletReqeust3</servlet-name>
    <url-pattern>/servlet/ServletReqeust3</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletReqeust4</servlet-name>
    <url-pattern>/servlet/ServletReqeust4</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletReqeust5</servlet-name>
    <url-pattern>/servlet/ServletReqeust5</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletRequest6</servlet-name>
    <url-pattern>/servlet/ServletRequest6</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletRequest7</servlet-name>
    <url-pattern>/servlet/ServletRequest7</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletRequest8</servlet-name>
    <url-pattern>/servlet/ServletRequest8</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletRequest9</servlet-name>
    <url-pattern>/servlet/ServletRequest9</url-pattern>
  </servlet-mapping>    
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

User.java

import java.io.Serializable;
import java.util.Arrays;
//属性名和表单控件的名字一致
public class User implements Serializable {

    private String username ;

    private String[] password ;

    private String gander ;

    private String[] loves ;

    private String graduation ;

    private String bake ;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String[] getPassword() {
        return password;
    }

    public void setPassword(String[] password) {
        this.password = password;
    }


    public String getGander() {
        return gander;
    }

    public void setGander(String gander) {
        this.gander = gander;
    }

    public String[] getLoves() {
        return loves;
    }

    public void setLoves(String[] loves) {
        this.loves = loves;
    }

    public String getGraduation() {
        return graduation;
    }

    public void setGraduation(String graduation) {
        this.graduation = graduation;
    }

    public String getBake() {
        return bake;
    }

    public void setBake(String bake) {
        this.bake = bake;
    }

    @Override
    public String toString() {
        return "User [username=" + username + ", password="
                + Arrays.toString(password) + ", gander=" + gander + ", loves="
                + Arrays.toString(loves) + ", graduation=" + graduation
                + ", bake=" + bake + "]";
    }

//  @Override
//  public String toString() {
//      return "User [username=" + username + ", password="
//              + Arrays.toString(password) + "]";
//  }

}

ServletRequest1.java

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ServletRequest1 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter() ;

        String contextpath = request.getContextPath() ;
        String  localAddr =  request.getLocalAddr() ;
        int localport = request.getLocalPort() ;
        StringBuffer url = request.getRequestURL() ;
        String uri = request.getRequestURI() ;
        String romoteaddr = request.getRemoteAddr() ;
        int rport = request.getRemotePort() ;
        String host = request.getRemoteHost() ;
        String method = request.getMethod() ;
        String query = request.getQueryString() ;

        out.write("获得上下文路径： " + contextpath + "<br>") ;  //"/" + 工程路径 
        out.write("获取服务器的IP地址：" + localAddr + "<br>") ;
        out.write("获取服务器的端口号：" + localport + "<br>") ;
        out.write("获取浏览器的请求地址：" + url + "<br>") ;
        out.write("获取浏览器的ip地址：" + romoteaddr + "<br>") ;
        out.write("获取浏览器访问的URI:：" + uri + "<br>") ;  // contextpath + "资源地址"
        out.write("获取客户端访问的端口号：" + rport + "<br>") ;
        out.write("获取客户端的机器Ip:：" + host + "<br>") ;
        out.write("获取请求方式：" + method + "<br>") ;
        out.write("获取请求参数：" + query + "<br>") ;

    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}

在浏览器输入http://localhost:8080/day0900httpServletRequest/servlet/ServletRequest1，结果如下

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2、获得客户机请求头

getHead(name)方法 

getHeaders(String name)方法 

getHeaderNames方法

ServletRequest2.java

import java.io.IOException;
import java.util.Enumeration;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//获取请求头信息
public class ServletRequest2 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");

        //获取单个请求头信息
//      String value = request.getHeader("Accept-Language") ;
//      System.out.println("Accept-Language:" + value);

        //获取单个名称多个值的请求头
//      Enumeration<String> enu = request.getHeaders("Accept-Language") ;
//      while(enu.hasMoreElements()){
//          String value = enu.nextElement() ;
//          System.out.println(value);
//      }

        //获取所有的请求头名称和值
        Enumeration<String> enu = request.getHeaderNames() ;
        while(enu.hasMoreElements()){
            String name = enu.nextElement() ;
            Enumeration<String> values = request.getHeaders(name) ;
            while(values.hasMoreElements()){
                String value = values.nextElement() ;
                System.out.println(name + ":" + value);
            }
        }
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}

在浏览器输入：http://localhost:8080/day0900httpServletRequest/servlet/ServletRequest2，浏览器会发送以下一段http的头信息到服务器：

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服务器接收到了这些头信息之后，servlet处理并输出以下结果：

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3、获得客户机请求参数(客户端提交的数据)

getParameter(name)方法

getParameterValues（String name）方法

getParameterNames方法 

getParameterMap方法  //做框架用，非常实用

getInputStream

<!DOCTYPE html>
<html>
  <head>
    <title>register.html</title>

    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="this is my page">
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">

    <!--<link rel="stylesheet" type="text/css" href="http://blog.163.com/faith_yee/blog/./styles.css">-->

  </head>

  <body>
        <form action="/day09_00_httpServletRequest/servlet/ServletReqeust3" method="post">
            姓名： <input type="text" name = "username"><br>
            密码： <input type="password" name = "password"><br>
            确认密码： <input type="password" name = "password"><br>
            <input type = "submit" value = "注册">
        </form>
  </body>
</html>

ServletReqeust3.java

import java.beans.PropertyDescriptor;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.Enumeration;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.beanutils.BeanUtils;


//演示获取客户端的请求参数
public class ServletReqeust3 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");

//      tes1(request) ;
//      tes2(request) ;
//      tes3(request) ;
//      tes4(request) ;
//      tes5(request) ;
        tes6(request) ;
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }
    //1.拿到单个表单控件的的值:拿取姓名的值
    public void tes1(HttpServletRequest request){
        String name = request.getParameter("username") ;
        System.out.println(name);
    }

    //2.拿到表单控件的的值（同名控件的多个值）:拿取密码的值
    public void tes2(HttpServletRequest request){
        String[] password = request.getParameterValues("password") ;
        for (String string : password) {
            System.out.println(string);
        }
    }

    //3.拿到所有控件的名字和值
    public void tes3(HttpServletRequest request){
        Enumeration<String> names = request.getParameterNames() ;
        while(names.hasMoreElements()){
            String name = names.nextElement() ;
            String[] values = request.getParameterValues(name) ;
            System.out.println(name + ":" + Arrays.asList(values));
        }
    }


    //4.将获取的参数应当封装到javabean中: 采用PropertyDesciptor
    public void tes4(HttpServletRequest request){
        User user = new User() ;
        System.out.println("封装前： " + user);
        //获取所有的表单控件的名字
        Enumeration<String> names = request.getParameterNames() ;
        //循环封装
        while(names.hasMoreElements()){
            //拿取控件的名字
            String name = names.nextElement() ;
            //控件的值
            String[] values = request.getParameterValues(name) ;

            try {
                PropertyDescriptor pd = new PropertyDescriptor(name, User.class) ;  //拿到User对象的属性name的属性描述器
                Method m = pd.getWriteMethod() ;   //拿到属性的set方法
                //为了兼容jdk1.4的版本，虚拟机会将values拆分成一个一个值进行传递
                if(values !=null && values.length == 1)
                    m.invoke(user, values) ;
                else{
                    //方法一：强转成一个object
                    //m.invoke(user, (Object)values) ;
                    //方法二：创建一个数组
                    m.invoke(user, new Object[]{values}) ;
                }
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

        System.out.println("封装后： " + user);
    }

    //5.将获取的参数应当封装到javabean中: 采用BeanUtils
    public void tes5(HttpServletRequest request){
        User user = new User() ;
        System.out.println("封装前： " + user);
        //获取所有的表单控件的名字
        Enumeration<String> names = request.getParameterNames() ;
        //循环封装
        while(names.hasMoreElements()){
            //拿取控件的名字
            String name = names.nextElement() ;
            //控件的值
            String[] values = request.getParameterValues(name) ;

            try {
                BeanUtils.setProperty(user, name, values) ;
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }

        System.out.println("封装后： " + user);
    }

    //6.将获取的参数应当封装到javabean中: 采用BeanUtils的另一种方式
    public void tes6(HttpServletRequest request){
        User user = new User() ;
        System.out.println("封装前： " + user);
        //拿到键值对的映射
        Map<String,String[]> map = request.getParameterMap() ;

        for (Map.Entry<String, String[]> entry : map.entrySet()) {   //entry就是键值对
            String name = entry.getKey() ;  //拿到键
            String[] values = entry.getValue() ;  //拿到值

            try {
                BeanUtils.setProperty(user, name, values) ;
            } catch (Exception e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }

        System.out.println("封装后： " + user);
    }

    //7.终极必杀技 (采用beanUtils类)(推荐)
    public void tes7(HttpServletRequest request){
        User user = new User() ;
        System.out.println("封装前： " + user);
        try {
            BeanUtils.populate(user, request.getParameterMap()) ;
        } catch (IllegalAccessException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        System.out.println("封装后： " + user);
    }
}

在浏览器中输入：http://localhost:8080/day0900httpServletRequest/register.html，弹出以下页面，并输入信息：

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输入信息之后，信息会提交到服务器并servlet处理之后得出以下结果：

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4、各种表单输入项数据的获取

text、password、radio、checkbox、file、select、textarea、 hidden、image、button给js编程用

<!DOCTYPE html>
<html>
  <head>
    <title>register.html</title>

    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="this is my page">
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">

    <!--<link rel="stylesheet" type="text/css" href="http://blog.163.com/faith_yee/blog/./styles.css">-->

  </head>
     <script type="text/javascript">
        function tosubmit(){
            document.forms[0].method = "get" ;
            document.forms[0].submit() ;
        }
     </script>
  <body>
        <form action="/day09_00_httpServletRequest/servlet/ServletReqeust4" method="post"> 
            姓名： <input type="text" name = "username"><br>
            密码： <input type="password" name = "password"><br>
            确认密码： <input type="password" name = "password"><br>
            性别：  <input type="radio" name = "gander" value = "male">男<input type="radio" name = "gander" value = "female">女<br>
            爱好： <input type="checkbox" name = "loves" value = "lanqiou">篮球<input type="checkbox" name = "loves" value = "football">足球<input type="checkbox" name = "loves" value = "handball">排球<br>
            学历： <select name = "graduation">
                <option value = "daxue">大学</option>
                <option value = "zhongxue">中学</option>
                <option value = "xiaoxue">小学</option>
            </select><br>
            备注：<textarea rows="5" cols="20" name = "bake">大神，留下你的足迹吧!!!</textarea><br>
            <!-- <input type = "submit" value = "注册"> -->
            <input type = "button" value = "注册" onclick="tosubmit()">
        </form>
  </body>
</html>

ServletReqeust4.java

import java.io.IOException;
import java.lang.reflect.InvocationTargetException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.beanutils.BeanUtils;

//演示封装所有表单控件的值
public class ServletReqeust4 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");

        User user = new User() ;
        System.out.println("封装前： " + user);
        try {
            BeanUtils.populate(user, request.getParameterMap()) ;
        } catch (IllegalAccessException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        System.out.println("封装后： " + user);
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}

在浏览器中输入：http://localhost:8080/day0900httpServletRequest/register1.html，弹出以下页面，并填写选项提交，把信息提交到了服务器中：

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服务器反馈如下信息：

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5、请求参数的中文乱码问题

浏览器是什么编码就以什么编码传送数据？

解决：
request.setCharacterEncoding(“UTF-8”);//POST有效

new String(username.getBytes(“ISO-8859-1”),“UTF-8”);//GET方式

超链接：<a href=“/JavaWeb/RequestDemo2?name=中国”>cn</a>//GET方式

更改Tomcat的配置解决URL编码问题：<Connector URIEncoding=“UTF-8”/>

<!DOCTYPE html>
<html>
  <head>
    <title>register.html</title>

    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="this is my page">
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">

    <!--<link rel="stylesheet" type="text/css" href="http://blog.163.com/faith_yee/blog/./styles.css">-->

  </head>

  <body>
        <form action="/day09_00_httpServletRequest/servlet/ServletReqeust5" method="get">
            姓名： <input type="text" name = "username"><br>
            <input type = "submit" value = "注册">
        </form>
  </body>
</html>

ServletReqeust5.java

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//演示中文乱码的解决
public class ServletReqeust5 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        response.setContentType("text/html;charset=UTF-8");

        //post方式提交的乱码解决
        //request.setCharacterEncoding("UTF-8");  //将请求数据用utf-8进行解码,只能针对post方式

        //针对get方式解决
        String name = request.getParameter("username") ;
        name = new String(name.getBytes("iso-8859-1"),"UTF-8") ;   //此种方式针对少量的中文

        //当多个控件中都存在中文的时候，此时推荐修改服务器的编码,找出服务器server.xml文件，修改<connector>里的URIEncoding属性为"UTF-8"
        System.out.println(name);

    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}

来浏览器中输入：http://localhost:8080/day0900httpServletRequest/login.html，弹出以下页面：

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输入信息后提交到了服务端，服务端的servlet处理完后得到以下结果：

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三、request对象实现请求转发：

请求转发指一个web资源收到客户端请求后，通知服务器去调用另外一个web资源进行处理。

request对象提供了一个getRequestDispatcher方法，该方法返回一个RequestDispatcher对象，调用这个对象的forward方法可以实现请求转发。

request对象同时也是一个域对象，开发人员通过request对象在实现转发时，把数据通过request对象带给其它web资源处理。

setAttribute方法 

getAttribute方法  

removeAttribute方法

getAttributeNames方法

包含：

包含：Servelt(源组件)把其他web组件(目标组件)生成的响应结果包含到自身的响应结果中。

ServletRequest6.java

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//演示请求转发
public class ServletRequest6 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");

        //请求对象也是一个域对象
        request.setAttribute("name", "任盈盈") ;
        PrintWriter out = response.getWriter() ;
        //out.write("哈哈哈啊啊") ;  //页面上输不出来
        //out.flush() ;   //不能再转发之前提交

        //请求转发 (先清空了缓冲区)
//      RequestDispatcher rd = request.getRequestDispatcher("/servlet/ServletRequest7") ;
        RequestDispatcher rd = request.getRequestDispatcher("ServletRequest7") ;
        rd.forward(request, response) ;


        /*
         *  ServletContext对象的请求转发与request对象的请求转发的不同：
         *        1.request对象的请求转发可以写相对路径, ServletContext对象的请求转发只能写绝对路径
         * */
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}

ServletRequest7.java

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ServletRequest7 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");

        String name = (String) request.getAttribute("name") ;
        System.out.println(name);
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}

在浏览器中输入： http://localhost:8080/day0900httpServletRequest/servlet/ServletRequest6，在服务器中输出的结果为：任盈盈

四、RequestDispather

1、表示请求分发器，它有两个方法：

forward():把请求转发给目标组件

public void forward(ServletRequest request,ServletResponse response)throws ServletException,java.io.IOException

include():包含目标组件的响应结果

public void include(ServletRequest request,ServletResponse response)throws ServletException,java.io.IOException

2、得到RequestDispatcher对象

1、ServletContext对象的getRequestDispather(String path1) path1必须用绝对路径，即以”/”开头，若用相对路径会抛出异常IllegalArgumentException

2、ServletRequest对象的getRequestDispatcher(String path2) path2可以用绝对路径也可以用相对路径

3、dispatcher.forward(request,response)的处理流程：

1、清空用于存放响应正文数据的缓冲区

2、如果目标组件为Servlet或JSP，就调用它们，把它们产生的响应结果发送到客户端；如果目标组件为文件系统中的静态HTML文档，就读取文档中的数据并把它发送给客户端。

特点：

1、由于forward()方法先清空用于存放响应正文数据的缓冲区，因此源组件生成的响应结果不会被发送到客户端，只有目标组件生成的响应结果才会被送到客户端。

2、如果源组件在进行请求转发之前，已经提交了响应结果（如调用了response的flush或close方法），那么forward（）方法会抛出IllegalStateException。为了避免该异常，不应该在源组件中提交响应结果。

4、include()方法的处理流程：

1、如果目标组件为Servlet或JSP，就执行它们，并把它们产生的响应正文添加到源组件的响应结果中；如果目标组件为HTML文档，就直接把文档的内容添加到源组件的响应结果中。

2、返回到源组件的服务方法中，继续执行后续代码块。

特点：

1、源组件与被包含的目标组件的输出数据都会被添加到响应结果中。

2、在目标组件中对响应状态代码或者响应头所做的修改都会被忽略。

ServletRequest8.java

import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//演示请求包含
public class ServletRequest8 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");

        RequestDispatcher rd = request.getRequestDispatcher("ServletRequest9") ;

        rd.include(request, response) ;

        String name = (String) request.getAttribute("name" ) ;
        System.out.println(name);

        response.getWriter().write("你好") ;


    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}

ServletRequest9.java

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ServletRequest9 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");

        request.setAttribute("name", "令狐冲") ;
        response.getWriter().write("中国") ;

    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}

在浏览器中输入：http://localhost:8080/day0900httpServletRequest/servlet/ServletRequest8，页面返回的结果是：

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同时，服务器也打印出了

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五、请求范围：

1、web应用范围内的共享数据作为ServeltContext对象的属性而存在(setAttribute)，只要共享ServletContext对象也就共享了其数据。

2、请求范围内的共享数据作为ServletRequest对象的属性而存在(setAttribute)，只要共享ServletRequest对象也就共享了其数据。

六、重定向

重定向机制的运作流程

1、用户在浏览器端输入特定URL，请求访问服务器端的某个组件

2、服务器端的组件返回一个状态码为302的响应结果。

3、当浏览器端接收到这种响应结果后，再立即自动请求访问另一个web组件

4、浏览器端接收到来自另一个web组件的响应结果。

HttpServeltResponse的sendRedirect(String location)用于重定向

特点

a. Servlet源组件生成的响应结果不会被发送到客户端。response.sendRedirect(String location)方法一律返回状态码为302的响应结果。

b. 如果源组件在进行重定向之前，已经提交了响应结果，会抛出IllegalStateException。为了避免异常，不应该在源组件中提交响应结果。

c. 在Servlet源组件重定向语句后面的代码也会执行。

d. 源组件和目标组件不共享同一个ServletRequest对象。

e. 对于sendRedirect(String location)方法的参数，如果以“/”开头，表示相对于当前服务器根路径的URL。以“http"//”开头，表示一个完整路径。

f. 目标组件不必是同一服务器上的同一个web应用的组件，它可以是任意一个有效网页。

请求转发和请求重定向的区别：

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会话管理之Cookie

一、会话

1、问题：什么是会话？

会话可简单理解为：用户开一个浏览器，点击多个超链接，访问服务器多个web资源，然后关闭浏览器，整个过程称之为一个会话。

2、会话过程中要解决的一些问题？

每个用户在使用浏览器与服务器进行会话的过程中，不可避免各自会产生一些数据，程序要想办法为每个用户保存这些数据。

例如：用户点击超链接通过一个servlet购买了一个商品，程序应该想办法保存用户购买的商品，以便于用户点结帐servlet时，结帐servlet可以得到用户购买的商品为用户结帐。

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思考：用户购买的商品保存在request或servletContext中行不行？

二、保存会话数据的两种技术

1、Cookie

Cookie是客户端技术，程序把每个用户的数据以cookie的形式写给用户各自的浏览器。当用户使用浏览器再去访问服务器中的web资源时，就会带着各自的数据去。这样，web资源处理的就是用户各自的数据了。

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2、HttpSession

Session是服务器端技术，利用这个技术，服务器在运行时可以为每一个用户的浏览器创建一个其独享的HttpSession对象，由于session为用户浏览器独享，所以用户在访问服务器的web资源时，可以把各自的数据放在各自的session中，当用户再去访问服务器中的其它web资源时，其它web资源再从用户各自的session中取出数据为用户服务。

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三、Cookie API

javax.servlet.http.Cookie类用于创建一个Cookie，response接口中定义了一个addCookie方法，它用于在其响应头中增加一个相应的Set-Cookie头字段。同样，request接口中也定义了一个getCookies方法，它用于获取客户端提交的Cookie。

Cookie类的方法：

public Cookie(String name,String value)

setValue与getValue方法 

setMaxAge与getMaxAge方法 (秒)

setPath与getPath方法

setDomain与getDomain方法

getName方法

四、Cookie细节

1、一个Cookie只能标识一种信息，它至少含有一个标识该信息的名称（NAME）和设置值（VALUE）。

2、一个WEB站点可以给一个WEB浏览器发送多个Cookie，一个WEB浏览器也可以存储多个WEB站点提供的Cookie。

3、浏览器一般只允许存放300个Cookie，每个站点最多存放20个Cookie，每个Cookie的大小限制为4KB。

4、如果创建了一个cookie，并将他发送到浏览器，默认情况下它是一个会话级别的cookie（即存储在浏览器的内存中），用户退出浏览器之后即被删除。若希望浏览器将该cookie存储在磁盘上，则需要使用maxAge，并给出一个以秒为单位的时间。将最大时效设为0则是命令浏览器删除该cookie。

5、注意，删除cookie时，path必须一致，否则不会删除

6、浏览器到底带不带Cookie，谁说了算呢？

浏览器到底带不带Cookie是由浏览器说了算。
浏览器通过判断  你在地址栏中敲入的资源地址. starWith(在硬盘上存储的Cookie里面存储的路径) 为true ,那就带，否则就不带.

实验：/day0901cookie 工程架构：

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配置文件web.xml内容如下：

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
    xmlns="http://java.sun.com/xml/ns/javaee" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <display-name></display-name>
  <servlet>
    <servlet-name>ServletCookie1</servlet-name>
    <servlet-class>com.heima.cookie.ServletCookie1</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletCookie2</servlet-name>
    <servlet-class>com.heima.cookie.ServletCookie2</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletDemo1</servlet-name>
    <servlet-class>com.heima.cookie1.ServletDemo1</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletCookie3</servlet-name>
    <servlet-class>one.ServletCookie3</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ServletCookie4</servlet-name>
    <servlet-class>one.ServletCookie4</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>MainServlet</servlet-name>
    <servlet-class>one.MainServlet</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ShowAllBookServlet</servlet-name>
    <servlet-class>two.servlet.ShowAllBookServlet</servlet-class>
  </servlet>
  <servlet>
    <servlet-name>ShowDetailInfoServlet</servlet-name>
    <servlet-class>two.servlet.ShowDetailInfoServlet</servlet-class>
  </servlet>


  <servlet-mapping>
    <servlet-name>ServletCookie1</servlet-name>
    <url-pattern>/servlet/ServletCookie1</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletCookie2</servlet-name>
    <url-pattern>/servlet/ServletCookie2</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletDemo1</servlet-name>
    <url-pattern>/ServletDemo1</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletCookie3</servlet-name>
    <url-pattern>/servlet/ServletCookie3</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ServletCookie4</servlet-name>
    <url-pattern>/servlet/ServletCookie4</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>MainServlet</servlet-name>
    <url-pattern>/servlet/MainServlet</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ShowAllBookServlet</servlet-name>
    <url-pattern>/servlet/ShowAllBookServlet</url-pattern>
  </servlet-mapping>
  <servlet-mapping>
    <servlet-name>ShowDetailInfoServlet</servlet-name>
    <url-pattern>/servlet/ShowDetailInfoServlet</url-pattern>
  </servlet-mapping>    
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

ServletCookie1.java

import java.io.IOException;
import java.io.PrintWriter;
import java.text.SimpleDateFormat;
import java.util.Date;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//演示记录上次访问的时间
public class ServletCookie1 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter() ;

        out.write("你上次访问的时间是： " ) ;

        //获取浏览器携带的Cookie
        Cookie[] cs = request.getCookies() ;
        //循环判断
        for (int i = 0; cs !=null && i < cs.length; i++) {
            Cookie c = cs[i] ;
            if(c.getName().equals("lastaccesstime")){
                //找到了存储上次访问时间的Cookie
                String time = c.getValue() ; 
                //转换成long
                long t = Long.parseLong(time) ;
                //采用SimpleDateformat
                SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss") ;
                String s = sdf.format(new Date(t)) ;

                out.write(s) ;
                out.write("<a href = ‘/day09_01_cookie/servlet/ServletCookie2‘>清空Cookie</a>") ;
                break ;
            }
        }
        //创建一个Cookie对象
        Cookie cookie = new Cookie("lastaccesstime",new Date().getTime() + "") ;
        //设置存活时间，一旦设置存活时间之后，那么Cookie将会存储在客户端的硬盘上
        cookie.setMaxAge(Integer.MAX_VALUE) ;
        //设置携带Cookie的路径
        cookie.setPath(request.getContextPath()) ;

        //cookie.setPath("/") ;  //表示服务器根路径，所以访问其他工程时，浏览器也带此Cookie

        //发送到客户端
        response.addCookie(cookie) ;
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}

ServletCookie2.java

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//演示删除Cookie
public class ServletCookie2 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");

        //新建一个Cookie,设置生命周期为0,立刻失效
        Cookie c = new Cookie("lastaccesstime","") ;

        c.setMaxAge(0) ;

        response.addCookie(c) ;
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}

第一次在浏览器中输入：http://localhost:8080/day0901cookie/servlet/ServletCookie1，得到如下结果：

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浏览器和服务器的信息头文件的内容如下：观察没有cookie产生

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第二次输入：http://localhost:8080/day0901cookie/servlet/ServletCookie1，页面产生了时间的信息，cookie生成

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查看信息头，显示cookie内容

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从浏览器的Internet选项里点击设置选项，弹出网站数据设置框，点击查看文件，查看cookie文件，

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文件夹显示输入工程路径后生成的cookie文件

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打开文件后查看cookie内容

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内容说明如下：

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实验二、记住登录用户名

ServletCookie3.java

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//记住用户名
/**
 * 产生一个登陆页面
 * @author Administrator
 *
 */
public class ServletCookie3 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter() ;

        String username = "" ;
        String pass = "" ;

        //拿到浏览器携带的Cookie
        Cookie[] cs = request.getCookies() ;
        for (int i = 0; cs != null && i < cs.length; i++) {
            Cookie c = cs[i] ;
            if(c.getName().equals("username")){
                //找到了存储用户名的Cookie
                username = c.getValue() ;
            }
            if(c.getName().equals("pass")){
                //找到了存储密码的Cookie
                pass = c.getValue() ;
            }
        }

        //拿取错误信息
        String error = (String) request.getAttribute("error") ;
        if(error != null)
            out.write(error) ;

        //创建登陆页面
        out.write("<form action = ‘/day09_01_cookie/servlet/ServletCookie4‘ method = ‘post‘>") ;
        out.write("姓名：<input type = ‘text‘ name = ‘username‘ value = ‘" + username +"‘><br>") ;
        out.write("密码：<input type = ‘password‘ name = ‘pass‘ value = ‘" + pass + "‘><br>") ;
        out.write("<input type = ‘checkbox‘ name = ‘remenber‘ value = ‘remenber‘>记住信息两周<br>") ;
        out.write("<input type = ‘submit‘ value = ‘登陆‘>") ;
        out.write("</form>") ;
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}

ServletCookie4.java

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/*
 *  此类有两个功能：
 *      1. 判断用户是否是合法用户
 *      2. 发送Cookie
 * */
public class ServletCookie4 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter() ;        

        //用户名和密码的逆序相同就认为是合法用户
        //拿到浏览器提交的数据
        String username = request.getParameter("username") ;
        String pass = request.getParameter("pass") ;
        String remenber = request.getParameter("remenber") ;

        //判断是否是合法用户
        String pass1 = new StringBuffer(pass).reverse().toString() ;
        if(username.equalsIgnoreCase(pass1)){
            //说明是合法用户
            //看是否要记录信息
            Cookie c = new Cookie("username",username) ;
            Cookie c1 = new Cookie("pass",pass) ;
            if(remenber == null){
                //说明要删除Cookie
                c.setMaxAge(0) ;
                c1.setMaxAge(0) ;
            }else{
                //记录信息
                c.setMaxAge(2*7*24*3600) ;
                c1.setMaxAge(2*7*24*3600) ;
            }
            c.setPath(request.getContextPath()) ;
            c1.setPath(request.getContextPath()) ;

            //发送Cookie
            response.addCookie(c) ;
            response.addCookie(c1) ;

            request.getRequestDispatcher("MainServlet").forward(request, response) ;
        }else{
            request.setAttribute("error", "用户名或者密码错误") ;
            request.getRequestDispatcher("ServletCookie3").forward(request, response) ;
        }
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}

MainServlet.java

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class MainServlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");

        response.getWriter().write("欢迎进入主界面") ;
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}

在浏览器输入：http://localhost:8080/day0901cookie/servlet/ServletCookie3，得到以下页面：

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输入姓名：abcde，密码：edcba，点击checkbox对话框，点击登录：得到以下画面：

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如果在输入界面输入：姓名：abcde，密码：sdasda，点击checkbox对话框，点击登录：

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实验三、利用cookie实现浏览记录

工程架构如下：

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Book.java

public class Book {

    private String id ;

    private String bookName ;

    private String author ;

    private float price ;

    private String discription ;


    public Book() {
    }

    public Book(String id, String bookName, String author, float price,
            String discription) {
        super();
        this.id = id;
        this.bookName = bookName;
        this.author = author;
        this.price = price;
        this.discription = discription;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getBookName() {
        return bookName;
    }

    public void setBookName(String bookName) {
        this.bookName = bookName;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public float getPrice() {
        return price;
    }

    public void setPrice(float price) {
        this.price = price;
    }

    public String getDiscription() {
        return discription;
    }

    public void setDiscription(String discription) {
        this.discription = discription;
    }

    @Override
    public String toString() {
        return "Book [id=" + id + ", bookName=" + bookName + ", author="
                + author + ", price=" + price + ", discription=" + discription
                + "]";
    }

}

BookUtils.java

import java.util.HashMap;
import java.util.Map;

import two.bean.Book;

public class BookUtils {

    public static Map<String,Book> map = new HashMap<String,Book>() ;

    static{
        map.put("1", new Book("1","葵花宝典","陈冠希",100,"欲练此功，必先练好java基础")) ;
        map.put("2", new Book("2","金瓶梅","阿娇",80,"一本好书啊，。。。。。。。")) ;
        map.put("3", new Book("3","水浒传","施耐庵",50,"3个女人和105个男人的故事")) ;
        map.put("4", new Book("4","辟邪剑谱","安培晋三",70,"小日本的绝世神功")) ;
        map.put("5", new Book("5","神雕侠侣","金庸",120,"一段感动天地的旷世绝恋")) ;
        map.put("6", new Book("6","红楼梦","曹雪芹",40,"一群女人和一个男人的故事")) ;
        map.put("7", new Book("7","韦小宝是怎么炼成的","屌丝",90,"羡慕啊。。。。。。。")) ;
    }
    //返回所有的书
    public static Map<String,Book> getAllBook(){
        return map ;
    }

    //返回根据id查找的书
    public static Book findBookById(String id){
        return map.get(id) ;
    }
}

ShowDetailInfoServlet.java

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.LinkedList;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import two.bean.Book;
import two.utils.BookUtils;

/**
 * 功能有两个：
 *      1.显示书的详细信息
 *      2.发送历史浏览记录
 * @author Administrator
 *
 */

public class ShowDetailInfoServlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter() ;

        //显示书的详细信息
        //拿到传递的参数名
        String id = request.getParameter("id") ;
        //获取书
        Book book = BookUtils.findBookById(id) ;
        //输出
        out.write(book + "<a href = ‘/day09_01_cookie/servlet/ShowAllBookServlet‘>返回继续浏览</a>") ;

        //生成一个历史记录Cookie
        String histroy = getHistory(request,id) ;
        //创建Cookie
        Cookie c = new Cookie("history", histroy) ;
        c.setMaxAge(Integer.MAX_VALUE) ;
        c.setPath(request.getContextPath()) ;
        response.addCookie(c) ;
    }
   //生成历史记录的Cookie
    /**
     *  浏览器携带的Cookie    当前点击的id       需要形成的Id字符串
     *    1. 无       1           1
     *    2. 1       1          1
     *    3. 1       2           2-1
     *    4. 1-2         1           1-2
     *    5  1-2        2            2-1
     *    6  1-2         3          3-1-2
     *    7  1-2-3       1                     1-2-3
     *    8  1-2-3      2           2-1-3
     *    9  1-2-3       3          3-1-2
     *    10 1-2-3      4           4-1-2
     */
    private String getHistory(HttpServletRequest request,String id) {
        Cookie history = null ;
        Cookie[] cs = request.getCookies() ;
        for (int i = 0; cs!=null && i < cs.length; i++) {
            if(cs[i].getName().equals("history")){
                //找到了历史记录的Cookie
                history = cs[i] ;
                break ;
            }
        }

        //考虑情况1
        if(history == null){
            return id ;
        }
        //考虑情况2,3
        String value = history.getValue() ;

        if(value.length() == 1){
            if(value.equals(id)){
                //点击的就是存储的历史记录
                return id ;
            }else
                return id + "-" + value ;
        }

        //考虑4,5,6
        LinkedList<String> list = new LinkedList<String>(Arrays.asList(value.split("-"))) ;
        if(value.length() == 3){
            int index = list.indexOf(id) ;
            if(index == -1){
                //点击的是没有浏览过的
                list.addFirst(id) ;
            }else{
                list.remove(index) ;
                list.addFirst(id) ;
            }
        }

        //考虑7,8,9,10
        if(value.length() > 3){
            int index = list.indexOf(id) ;
            if(index == -1){
                //点击的是没有浏览过的
                list.removeLast() ;
                list.addFirst(id) ;
            }else{
                list.remove(index) ;
                list.addFirst(id) ;
            }
        }

        //将list中的数据转换成需要的格式字符串
        StringBuffer sb = new StringBuffer(list.get(0)) ;
        for (int j = 1; j < list.size(); j++) {
            sb.append("-" + list.get(j)) ;
        }

        return sb.toString();
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}

ShowAllBookServlet.java

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import two.bean.Book;
import two.utils.BookUtils;
/**
 * 功能；
 *      1. 显示所有的书籍
 *      2. 显示历史浏览记录
 * @author Administrator
 *
 */
public class ShowAllBookServlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter() ;

        //显示所有的书籍
        out.write("本站有以下好书<br>") ;
        Map<String,Book> map = BookUtils.getAllBook()  ;
        for (Map.Entry<String, Book> entry : map.entrySet()) {
            Book b = entry.getValue() ;
            out.write( b.getBookName() + "<a href = ‘/day09_01_cookie/servlet/ShowDetailInfoServlet?id=" + b.getId() +"‘>查看详细信息</a><br>") ;
        }
        out.write("<br>") ;
        out.write("<br>") ;
        out.write("<br>") ;
        out.write("<br>") ;
        //显示历史浏览记录: 记录浏览记录的最近的3条记录  假设记录的值的形式是1-2-3
        Cookie[] cs = request.getCookies() ;
        for (int i = 0; i < cs.length; i++) {
            Cookie c = cs[i] ;
            if(c.getName().equals("history")){
                //找到了记录浏览记录的Cookie
                out.write("您的浏览历史记录如下：<br> ") ;
                String s = c.getValue() ;
                String[] ids = s.split("-") ;
                for (String id : ids) {
                    //拿到对应的书
                    Book book = BookUtils.findBookById(id) ;
                    out.write(book.getBookName() + "<br>") ;
                }
            }
        }
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}

在浏览器中输入：http://localhost:8080/day0901cookie/servlet/ShowAllBookServlet。进入菜单栏界面，如下：

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