标签：== 过程 数据类型 数据 名称 res request对象 eal tde
1、通过request对象获取
request.getServletContext();
2、通过HttpServlet对象获取
this.getServletContext();
1、获取MIME类型：
* MIME类型：在互联网通信过程中定义的一种文件数据类型
* 格式：大类型/小类型 如：text/html image/jpeg
* 获取：String getMimeType(String file)
package com.ServletContext; import javax.servlet.ServletContext; 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 java.io.IOException; @WebServlet("/servletContextDemo01") public class ServletContextDemo01 extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //1、通过request对象获取 ServletContext context1 = req.getServletContext(); //2、通过this获取 ServletContext context2 = this.getServletContext(); System.out.println(context1 == context2); //true //3、定义文件名称 String filename = "a.jpg"; //4、获取mime类型 String mimeType = context1.getMimeType(filename); System.out.println(mimeType);//image/jpeg } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { this.doGet(req, resp); } }
2、域对象：共享数据
1、setAttribute(String name, Object value)
2、getAttribute(String name)
3、removeAttribute(String name)
* ServletContext对象范围：所有用户请求的数据
3、获取文件的真实（服务器）路径
1、方法：String getRealPath(String path)
package com.ServletContext; import javax.servlet.ServletContext; 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 java.io.File; import java.io.IOException; @WebServlet("/servletContextDemo04") public class ServletContextDemo04 extends HttpServlet { @Override protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { //1、通过request对象获取 ServletContext context = req.getServletContext(); //获取文件的服务器路径 //web目录下资源访问 String realPath = context.getRealPath("/a.txt"); System.out.println(realPath);//D:\IntelliJ IDEA 2019.3.1\workspace\Web\out\artifacts\Web_war_exploded\a.txt //WEB-INF目录下的资源访问 String c = context.getRealPath("/WEB-INF/c.txt"); //src目录下资源访问 String d = context.getRealPath("/WEB-INF/classes/c.txt"); } @Override protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { this.doGet(req, resp); } }
Servlet（五）----ServletContext对象
标签：== 过程 数据类型 数据 名称 res request对象 eal tde
原文地址：https://www.cnblogs.com/21seu-ftj/p/12549391.html
