[ ajax登记验证 ]

2012-11-15

[ ajax注册验证 ]1.客户端:JSP%@ page languagejava pageEncodingGBK%htmlheadtitleindex.j

[ ajax注册验证 ]
1.客户端:JSP

<%@ page language="java" pageEncoding="GBK"%><html><head><title>index.jsp</title></head><mce:script type="text/javascript"><!--var xhr = false;function checkUserName(){//1.创建XMLHttpRequest对象；//IE Browser:try{       xhr = new ActiveXObject("Microsoft.XMLHTTP");}catch(e){try{xhr = new ActiveXObject("Msxml2.XMLHTTP");}catch(e){xhr = false;}}if(!xhr&&typeof XMLHttpRequest!="undefined"){xhr = new XMLHttpRequest();}//2.发出请求：var url ="serverPort?username="+escape(document.userForm.elements("name").value);xhr.open("POST",url,true);xhr.onreadystatechange = process;xhr.send(null);}function process(){if(xhr.readyState == 4){if(xhr.status == 200){document.getElementById("userSpan").innerHTML = xhr.responseText;}}}// --></mce:script><body><form action="" method="post" name="userForm"><table><caption>用户注册！</caption><tr><td>用户名：</td><td><input type="text" name="name" onblur="checkUserName()"><span id="userSpan">*</span></td></tr><tr><td>密码：</td><td><input type="password" name="password" ></td></tr></table></form></body></html>

2.服务端:Servlet

package servlet;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;public class ServerPort extends HttpServlet{private static final long serialVersionUID = 1L;public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {response.setContentType("text/html;charset=GBK");String userName = request.getParameter("username");PrintWriter out = response.getWriter();if(userName.trim().length()==0||userName==null){out.println("<font color='red'>用户名不能为空!</font>");}else if("neyjar".equals(userName)){out.println("<font color='red'>用户已存在!</font>");}else{out.println("<font color='blue'>可以使用此用户名!</font>");}}public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request, response);}}

3.web.xml中配置那个Servlet:

 <servlet>  <servlet-name>servletPort</servlet-name>  <servlet-class>servlet.ServerPort</servlet-class>  </servlet>  <servlet-mapping>  <servlet-name>servletPort</servlet-name>  <url-pattern>/serverPort</url-pattern>  </servlet-mapping>

这就是全部了! 1 楼 kevintang 2010-12-13 不错，详细说明了每个技术点。现在项目中可能都要从数据库中提取数据了。
这个得根据个人的需要添加了 2 楼逍遥虎 2010-12-16 写的不错，但是只是针对ajax刚入门的人来说是一个很好的例子，你还可以解释一下为什么要判断等于4、200。我认为刚入门ajax对这些地方都是比较模糊的。如果只是追求好用还不如用jquery。 3 楼 lao1984wang 2011-04-07 怎么照着做不对啊。。。。。。

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