神奇的Ajax

1.Ajax: 不刷新整个页面，只刷新局部

1.1无刷新的好处：

1.1.1 提供连续的用户体验

1.1.2提供类似C/S的交互效果，操作更方面

2.常用属性:

2.1onreadystatechange：指定回调函数 readystate: XMLHttpRequest的状态信息

2.2status：HTTP的状态码

        2.3 responseText：获得响应的文本内容

2.4responseXML：获得响应的XML文档对象

3.使用Ajax：

技术实现异步交互

创建XMLHttpRequest对象

通过 XMLHttpRequest对象设置请求信息

向服务器发送请求 创建回调函数，根据响应状态动态更新页面

代码块

登录login

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









		用户名：

		密码：

		
		
		

package com.zking.servlet;

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

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 com.zking.dao.T277Dao;
import com.zking.entity.T277;


@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		System.out.println("来了 老弟");
		//接收数据
		String uname = request.getParameter("uname");
		String upwd = request.getParameter("upwd");
		String uinfo = request.getParameter("uinfo");
		System.out.println("uname:"+uname);
		System.out.println("upwd:"+upwd);
		request.setCharacterEncoding("utf-8");
		
		//获取响应的 输出流
		PrintWriter out = response.getWriter();
		T277Dao dd = new T277Dao();
		ArrayList tt = dd.getAll();
		int c = 0;
		for (int j = 0; j < tt.size(); j++) {
			if(tt.get(j).getUname().equals(uname) && tt.get(j).getUpwd().equals(upwd)) {
				c=1;
				break;
			}else {
				c=2;
			}
			}
			if(c==1) {
				out.print("ok");
			}else {
				out.print("no");
			}
			out.close();
		}
			
		
	
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}