1.小实例:注册用户名是否存在。
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1.小实例:注册用户名是否存在。
Favour 发表于2年前
1.小实例:注册用户名是否存在。
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<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
<script type="text/javascript">
	function checkUserName(){
		var userName=document.getElementById("userName").value;
		var xmlHttp;
		if(window.XMLHttpRequest){
			xmlHttp=new XMLHttpRequest();
		}else{
			xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
		}
		xmlHttp.onreadystatechange=function(){
			if(xmlHttp.readyState==4 && xmlHttp.status==200){
				alert(xmlHttp.responseText);
				var dataObj=eval("("+xmlHttp.responseText+")");
				if(dataObj.exist){
					document.getElementById("tip").innerHTML="<img src='no.png'/>&nbsp;该用户名已经存在";
				}else{
					document.getElementById("tip").innerHTML="<img src='ok.png'/>&nbsp;该用户名可用";
				}
			}
		};
		xmlHttp.open("get", "GetAjaxInfoServlet?action=checkUserName&userName="+userName, true);
		
	    xmlHttp.send();
	}
</script>
</head>
<body>
<table>
	<tr>
		<th>用户注册</th>
	</tr>
	<tr>
		<td>用户名:</td>
		<td><input type="text" id="userName" name="userName" onblur="checkUserName()"/>&nbsp;&nbsp;<font id="tip"></font></td>
	</tr>
	<tr>
		<td>密码:</td>
		<td><input type="text" id="password" name="password"/></td>
	</tr>
	<tr>
		<td>确认密码:</td>
		<td><input type="text" id="password2" name="password2"/></td>
	</tr>
	<tr>
		<td><input type="submit" value="注册"/></td>
		<td><input type="button" value="重置"/></td>
	</tr>
</table>
</body>
</html>

 

package 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();
	}
	
}

 

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
	xmlns="http://java.sun.com/xml/ns/javaee" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
	xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
	http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
  <servlet>
    <description>This is the description of my J2EE component</description>
    <display-name>This is the display name of my J2EE component</display-name>
    <servlet-name>GetAjaxInfoServlet</servlet-name>
    <servlet-class>web.GetAjaxInfoServlet</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>GetAjaxInfoServlet</servlet-name>
    <url-pattern>/GetAjaxInfoServlet</url-pattern>
  </servlet-mapping>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

 

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