ajax与后台的交互demo

这个demo主要演示ajax与tomcat服务器的简单交互操作！

思路：在输入框中输入用户名，如用户名为空，则显示“请输入用户名”；如输入的用户名已存在，则显示“错号”图片；不存在相同的用户名，则显示“对号”图片

源码链接：https://github.com/longhaicheng/ajax-and-java(可以给我一个star就好了！)

• 目录截图
  

• 前端界面（比较简单）
  

• 未输入
  

• 随机输入用户名
  

• 输入已存在的用户名
  

• 代码：
  前端界面：

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>








	
	
	
	

	
	点击

服务器端：

package testservlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.net.URLDecoder;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class test
 */
@WebServlet("/test")
public class test extends HttpServlet {
	private String teacher = "张三";
	private static final long serialVersionUID = 1L;

	/**
	 * @see HttpServlet#HttpServlet()
	 */
	public test() {
		super();
		// TODO Auto-generated constructor stub
	}

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		request.setCharacterEncoding("utf-8"); // 设置编码
		response.setCharacterEncoding("utf-8"); // 设置编码
		String name = request.getParameter("username"); // 得到前面的值
		String username = URLDecoder.decode(name, "utf-8"); // 对URL进行编码
		String url = "";
		if (teacher.equals(username.trim())) {
			url = "image/false.png";
		} else {
			url = "image/true.png";
		}
		// 返回路径
		response.getWriter().println(url);
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
	}

}