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这几天一直在反复学习的内容，Servlet，Filter，Session，MySQL，jsp。
今天以一个完整的小项目作为BS入门基础的总结。
用户在jsp页面上输入用户名和密码，经过filter进入servlet，与数据库中的数据进行匹配，密码和用户名输入正确则跳转欢迎界面，否则返回登录页面重新输入。
项目ProjectOne_FirstTryBS 有：
src底下有：四个package（servlet，filter，model，util）和一个数据库配置文件jdbc.properties。
WebContent底下有：jsp，META-INF，WEB-INF和web.xml。
具体索引如图：
lib里面有很多类库，我压缩成.rar放在资源上了。
我这里用的是tomcat3.0，所以web.xml是不用自己配置的。
首先，我写了三个jsp页面：login.jsp ，error.jsp，welcome.jsp。login负责用户输入用户名和密码，是个登录页面；error是用户输入错误时跳转的一个中转页面；welcome是登陆成功的欢迎页面。images文件夹里面有一张背景图片bg.jpg。
login.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ page import="javax.servlet.http.*" %>
<%@ page import="com.yan.model.User"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>JSP登陆界面</title>
</head>
<body style="background:url('images/bg.jpg') no-repeat;">
<div style="text-align:center; position:absolute; top:30%; left:45%" >
<div style="width:100px; margin:0 auto;" >
<form name="form" action="../../ProjectOne_FirstTryBS/checkservlet" method="post" >
<h4>用户名：</h4><input type="text" name="username" ><br>
<h4>密 码：</h4><input type="password" name="passwd" ><br><br>
<input type="submit" name="submit" value="登录">
<input type="reset" name="reset" value="重置">
</form>
</div>
</div>
</body>
</html>form标签下action指向你项目下的servlet文件，因为servlet里面有验证数据库中的用户名和密码，而filter是默认每一个请求之后都会进入的。在正常情况下，应该是通过filter进入servlet的。
error.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>中转站界面</title>
</head>
<body style="background:url('images/bg.jpg') no-repeat;">
<div style="text-align:center; position:absolute; top:30%; left:45%" >
<div style="width:100px; margin:0 auto;" >
<input type="submit" value="返回" onclick="window.location.href='login.jsp'" />
</div>
</div>
</body>
</html>我的error.jsp上只有一个返回login.jsp的按钮，目的就是能让地址从servlet回到login.jsp
welcome.jsp
<%@page import="com.yan.model.User"%>
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>jsp欢迎界面</title>
</head>
<body style="background:url('images/bg.jpg') no-repeat;">
<div style="text-align:center; position:absolute; top:30%; left:45%" >
<div style="width:100px; margin:0 auto;" >
<%
User user = (User)session.getAttribute("user");
%>
<div>
<h4>用户的ID是：</h4><%=user.getId() %><br/>
<h4>你的Name是：</h4><%=user.getName() %><br/>
<h4>你的Password是：</h4><%=user.getPasswd() %><br/>
</div>
</div>
</div>
</body>
</html>在脚本中，将user类放在session里面，获取用户输入的用户名和密码，以及数据库中对应的ID。
web.xml也放上来吧，至此，WebContent的内容就结束了。
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>ProjectOne_FirstTryBS</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
</web-app>
jbdc.porpertise
#mysql DB properties #MYSQL_DB_DRIVER_CLASS=com.mysql.jdbc.Driver #MYSQL_DB_URL=jdbc:mysql://localhost:3306/UserDB //3306是我连接MySQL的端口号，你写你的 #MYSQL_DB_USERNAME=pankaj #MYSQL_DB_PASSWORD=pankaj123 #Oracle DB Properties ORACLE_DB_DRIVER_CLASS=oracle.jdbc.driver.OracleDriver #ORACLE_DB_URL=jdbc:oracle:thin:@192.168.100.36:1521:TFS ORACLE_DB_URL=jdbc:oracle:thin:@10.50.9.63:1521:orcl ORACLE_DB_USERNAME=PBYL1030 ORACLE_DB_PASSWORD=pbtestforhr2014 #Oracle DB Properties 2 ORACLE_DB_DRIVER_CLASS2=oracle.jdbc.driver.OracleDriver ORACLE_DB_URL2=jdbc:oracle:thin:@192.168.100.36:1521:easdbtest ORACLE_DB_USERNAME2=PBYL1030 ORACLE_DB_PASSWORD2=pbyl20140418fortest mysqldriverclass=com.mysql.jdbc.Driver mysqljdbcurl=jdbc:mysql://主机IP地址:端口号/库名 mysqluser=root mysqlpassword=你的登录MySQL的密码
package com.yan.util;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;
import javax.sql.DataSource;
import org.apache.commons.dbcp.BasicDataSource;
import org.apache.commons.dbutils.QueryRunner;
public class OracleConnection {
private static DataSource dataSource;
private static void initOracle()
{
Properties props = new Properties();
InputStream in = null;
//props.load(ToSaveErrlog.class.getClassLoader().getResourceAsStream("save2logdb.properties"));
try {
in = OracleConnection.class.getClassLoader()
.getResourceAsStream("jdbc.properties");
props.load(in);
} catch (FileNotFoundException e) {
System.out.println("jdbc.properties not found");
e.printStackTrace();
} catch (IOException e) {
System.out.println("read error in jdbc.properties ");
e.printStackTrace();
}
BasicDataSource dbcpDataSource = new BasicDataSource();
dbcpDataSource.setUrl(props.getProperty("mysqljdbcurl"));
dbcpDataSource.setDriverClassName(props.getProperty("mysqldriverclass"));
dbcpDataSource.setUsername(props.getProperty("mysqluser"));
dbcpDataSource.setPassword(props.getProperty("mysqlpassword"));
dbcpDataSource.setDefaultAutoCommit(true);
dbcpDataSource.setMaxActive(10);
dbcpDataSource.setMaxIdle(5);
dbcpDataSource.setMaxWait(500);
OracleConnection.dataSource = (DataSource)dbcpDataSource;
System.out.println("Initialize dbcp...");
}
public static Connection getConnection()
{
try {
if(OracleConnection.dataSource==null){
initOracle();
return OracleConnection.dataSource.getConnection();
}else
{
return OracleConnection.dataSource.getConnection();
}
} catch (SQLException e) {
e.printStackTrace();
}
return null;
}
public static QueryRunner getQueryRunner(){
if(OracleConnection.dataSource==null){
initOracle();
return new QueryRunner(OracleConnection.dataSource);
}else
{
return new QueryRunner(OracleConnection.dataSource);
}
}
}
其中，name和passwd是用户自定义的，而id是用户不知道的，我在数据库中对id的定义是（写的不是正规语法，你们看得懂就行）：
'id' (int(8), NOT NULL, AUTO INCREMENT, PRIMARY KEY)
package com.yan.model;
import java.io.Serializable;
public class User implements Serializable {
private static final long serialVersionUID = -1734127774270588940L;
private String id;
private String name;
private String passwd;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPasswd() {
return passwd;
}
public void setPasswd(String passwd) {
this.passwd = passwd;
}
}
LogFilter.java
package com.yan.filter;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
//日志过滤器，记录登录过滤信息，可以显示在console，也可以录入数据库
@WebFilter(filterName = "logfilter",urlPatterns = {"/*"})
public class LogFilter implements Filter {
private FilterConfig fConfig;
public void init(FilterConfig fConfig) throws ServletException {
this.fConfig = fConfig;
}
public void destroy() {
this.fConfig = null;
}
//核心过滤部分
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
/*---------下面代码用于对用户请求执行预处理---------*/
//获取ServletContext对象，用于记录日志
ServletContext context = this.fConfig.getServletContext();
long before = System.currentTimeMillis();
System.out.println("开始过滤...");
//将请求转换成HttpServletRequest请求
HttpServletRequest hrequest = (HttpServletRequest)request;
//记录日志
context.log("Filter已经截获到用户的请求地址： " + hrequest.getServletPath());
//Filter只是链式处理，请求依然放行到目的地址
chain.doFilter(request, response);
/*---------下面代码用于对服务器响应执行后处理---------*/
long after = System.currentTimeMillis();
//记录日志
context.log("过滤结束");
//再次记录日志
context.log("请求被定位到" + hrequest.getRequestURI() + "所花的时间为: " + (after - before));
}
public LogFilter() {}
}
package com.yan.filter;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebFilter;
import javax.servlet.annotation.WebInitParam;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
//登录过滤器，记录用户是否登录
@WebFilter(filterName = "authorityfilter",
urlPatterns = {"/*"},
initParams = {
@WebInitParam(name = "encoding", value = "GBK"),
@WebInitParam(name = "loginPage", value = "/jsp/login.jsp"),
@WebInitParam(name = "checkservlet", value = "/checkservlet"),
@WebInitParam(name = "proLogin", value = "/jsp/welcome.jsp")
})
public class AuthorityFilter implements Filter {
private FilterConfig fConfig;
public AuthorityFilter() {}
public void destroy() {
this.fConfig = null;
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
//获取该filter的配置参数
String encoding = fConfig.getInitParameter("encoding");
String loginPage = fConfig.getInitParameter("loginPage");
String proLogin = fConfig.getInitParameter("proLogin");
String checkservlet = fConfig.getInitParameter("checkservlet");
//设置request编码用的字符集
request.setCharacterEncoding(encoding);
HttpServletRequest requ = (HttpServletRequest)request;
HttpSession session = requ.getSession(true);
//获取客户请求页面
String requestPath = requ.getServletPath();
//如果session范围的user为null，即没有登录
//并且用户请求的既不是登陆页面，也不是处理登录的页面
/* 1.如果user为null，即从未登陆过，应该跳转login页面
* 2.如果用户访问的不是login页面，应该跳转login页面
* 3.如果用户没有访问过checkservlet，应该跳转login页面
* */
if(session.getAttribute("user") == null
&& !requestPath.endsWith(loginPage)
&& !requestPath.endsWith(checkservlet)) {
//forward到登录页面
request.setAttribute("tip", "您还没有登录");
request.getRequestDispatcher(loginPage).forward(request, response);
} else {
//“放行”请求
chain.doFilter(request, response);
}
}
public void init(FilterConfig fConfig) throws ServletException {
this.fConfig = fConfig;
}
}
package com.yan.servlet;
import java.io.IOException;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import javax.swing.JOptionPane;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import com.mysql.jdbc.Connection;
import com.mysql.jdbc.PreparedStatement;
import com.yan.model.User;
import com.yan.util.OracleConnection;
import java.awt.*;
import javax.swing.*;
import java.util.regex.*;
@WebServlet("/checkservlet")
public class CheckServlet<AttenAudit> extends HttpServlet {
private static final long serialVersionUID = 1L;
public CheckServlet() {
super();
}
public void process (HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("现在开始执行CheckServlet.java");
String u = request.getParameter("username");
String p = request.getParameter("passwd");
String sql = "select * from User where name = ? and passwd = ? " ;
//u和p放在Object里面传给userList
List<User> userList = new ArrayList<User>();
try {
userList = OracleConnection.getQueryRunner().query(sql, new BeanListHandler<User>(User.class),new Object[]{u,p});
} catch (SQLException e) {
e.printStackTrace();
}
//userList的内容不为空代表输入的用户名和密码的组合在数据库中存在；为空则表示用户名或者密码错误
if(userList.size()>0) {
HttpSession session = request.getSession(true);
session.setAttribute("user", userList.get(0)); //取userList里面的第一组值Object[u,p]
request.getRequestDispatcher("/jsp/welcome.jsp").forward(request, response);
} else {
JOptionPane.showMessageDialog(null, "用户名或密码错误，请重新输入！", "哎呀呀", JOptionPane.WARNING_MESSAGE);
//response.sendRedirect("../jsp/error.jsp");
request.getRequestDispatcher("/jsp/error.jsp").forward(request, response);
}
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
process(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
process(request, response);
}
}
首先你要启动tomcat，然后在浏览器中输入http://localhost:8080/ProjectOne_FirstTryBS/login.jsp，进入login.jsp
输入错误的话，会有弹窗，然后console上也会有所反映。
跳转到error.jsp，再回到login.jsp。输入正确的话，
可以从通过以下语句传参，再从welcome.jsp提取。
request.getRequestDispatcher("/jsp/welcome.jsp").forward(request, response);
以上，就是全过程。
【Servlet】连接MySQL实现验证密码登录（附带详细解析及lib附件）
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原文地址：http://blog.csdn.net/chuck_0430/article/details/43239503
