一、工程目录结构

GetUsersListServlet.java

package com.cuit.hello.web;

import java.io.IOException;

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

public class GetUsersListServlet extends HelloServlet{
	
	private String name = "";
	
	//获取数据
	@Override
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
			response.setCharacterEncoding("utf-8");
			//JSON 数据格式
			String content = "{'name':'"+name+"','age':18,'sex':'男'}";
			
			response.getWriter().append(content);
		
	}
	
	//提交数据
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		
		//接收参数
		String nameStr = req.getParameter("name");
		
		name = nameStr;
		
		resp.setCharacterEncoding("utf-8");
		//JSON 数据格式
		String content = "{'name':'"+nameStr+"','age':28,'sex':'男'}";
		
		//Servlet上下文
		//不同的接口之间共享数据
		ServletContext context = getServletContext();
		context.setAttribute("name", nameStr);
		
		
		resp.getWriter().append(content);
	}

}

HelloServlet.java

package com.cuit.hello.web;

import java.io.IOException;

import javax.servlet.ServletConfig;
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;

@WebServlet(name = "Hello", urlPatterns = { "/Hello" })
public class HelloServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    public HelloServlet() {
        super();
    }
    
    @Override
    public void init(ServletConfig config) throws ServletException {
    	//servlet初始化时调用
    	super.init(config);
    }
    
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    	//init之后调用
    	super.service(req, resp);
    }
    
    @Override
    public void destroy() {
    	//摧毁时调用
    	super.destroy();
    }
    
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		response.setCharacterEncoding("utf-8");
		ServletContext context = getServletContext();
		response.getWriter().append("Hello "+context.getAttribute("name"));
	}

}

Web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" id="WebApp_ID" version="4.0">
  <display-name>01_HelloServlet</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>
  
  <servlet>
  		<servlet-name>GetUsersList</servlet-name>
  		<servlet-class>com.cuit.hello.web.GetUsersListServlet</servlet-class>
  </servlet>
  
  <servlet-mapping>
  		<servlet-name>GetUsersList</servlet-name>
  		<url-pattern>/GetUserList</url-pattern>
  </servlet-mapping>
</web-app>