Ajax实例

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1. ajax验证用户名

2. ajax二级联动

GetAjaxInfoServlet.java

package com.andrew.web;

import java.io.IOException;
import java.io.PrintWriter;

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

import net.sf.json.JSONArray;
import net.sf.json.JSONObject;

public class GetAjaxInfoServlet extends HttpServlet{

    private static final long serialVersionUID = 1L;

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        this.doPost(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=utf-8");
        String action=request.getParameter("action");
        if("checkUserName".equals(action)){
            this.checkUserName(request, response);
        }else if("ejld".equals(action)){
            this.ejld(request, response);
        }
        
    }

    
    private void checkUserName(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        PrintWriter out=response.getWriter();
        String userName=request.getParameter("userName");
        JSONObject resultJson=new JSONObject();
        if("jack".equals(userName)){
            resultJson.put("exist", true);
        }else{
            resultJson.put("exist", false);
        }
        out.println(resultJson);
        out.flush();
        out.close();
    }
    
    private void ejld(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        PrintWriter out=response.getWriter();
        String shengId=request.getParameter("shengId");
        JSONObject resultJson=new JSONObject();
        JSONArray jsonArray=new JSONArray();
        JSONObject temp=null;
        switch(Integer.parseInt(shengId)){
            case 1:{
                temp=new JSONObject();temp.put("id", 1);temp.put("text", "南京");jsonArray.add(temp);
                temp=new JSONObject();temp.put("id", 2);temp.put("text", "南通");jsonArray.add(temp);
                temp=new JSONObject();temp.put("id", 3);temp.put("text", "泰兴");jsonArray.add(temp);
                break;
            }
            case 2:{
                temp=new JSONObject();temp.put("id", 4);temp.put("text", "济南");jsonArray.add(temp);
                temp=new JSONObject();temp.put("id", 5);temp.put("text", "烟台");jsonArray.add(temp);
                temp=new JSONObject();temp.put("id", 6);temp.put("text", "蓬莱");jsonArray.add(temp);
                break;
            }
            case 3:{
                temp=new JSONObject();temp.put("id", 7);temp.put("text", "杭州");jsonArray.add(temp);
                temp=new JSONObject();temp.put("id", 8);temp.put("text", "宁波");jsonArray.add(temp);
                temp=new JSONObject();temp.put("id", 9);temp.put("text", "温州");jsonArray.add(temp);
                break;
            }
        }
        resultJson.put("rows", jsonArray);
        out.println(resultJson);
        out.flush();
        out.close();
    }
    
}

web.xml


      getAjaxInfoServlet
      com.andrew.web.GetAjaxInfoServlet


      getAjaxInfoServlet
      /getAjaxInfo


checkUserName.jsp

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









    

        
用户注册
    
    

        
用户名：
        
  
    
    

        
密码：
        

    
    

        
确认密码：
        

    
    

        

        

    




ejld.jsp

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









    

        
用户注册
    
    

        
用户名：
        
  
    
    

        
密码：
        

    
    

        
确认密码：
        

    
    

        

        

    




http://localhost:8080/HeadFirstAjaxJsonChap04/ejld.jsp
http://localhost:8080/HeadFirstAjaxJsonChap04/checkUserName.jsp
该用户名可用