首先是jsp页面和脚本，为了方便写在一个里面
这是一个很常见的检测用户名是否存在的功能
这里用的是struts
<%@ page contentType="text/html; charset=GBK" %>
<html>
<head>
<title>
ajax
</title>
</head>
<body bgcolor="#ffffff">
<h1>
<input name="username" type="text" maxlength="20" />
<input id="chk-name-btn" type="button" value="检测帐号" />
<div id="view_name"></div>
</h1>
</body>
</html>
<script language="javascript">
if (window.ActiveXObject &;amp;&;amp; !window.XMLHttpRequest) {
window.XMLHttpRequest=function() {
return new ActiveXObject((navigator.userAgent.toLowerCase().indexOf('msie 5') != -1) ? 'Microsoft.XMLHTTP' : 'Msxml2.XMLHTTP');
};
}//取得XMLHttpRequest对象
function testName(path){
//path是取得系统路径
var view_name=document.getElementById("view_name");
var req=new XMLHttpRequest();
if (req) {
req.onreadystatechange=function() {
if (req.readyState==4 &;amp;&;amp; req.status==200) {//判断状态，4是已发送，200已完成
if(req.responseText==0){
view_name.style.color='green';
view_name.innerHTML='该用户名可以正常使用';
}else if(req.responseText==1){
view_name.style.color='red';
view_name.innerHTML='该用户名已经被使用';
}else{
view_name.style.color='red';
view_name.innerHTML='该用户名含有非法字符！';
}
}
}
req.open('POST', path '/ajax.do');//struts
//req.open('POST', path '/ajax.servlet');//servlet
//req.open('POST', path '/ajax.action');//webwork
req.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
req.send("");//发送参数如果有参数req.send("username=" user_name);用request取得
}
}
</script>
这个jsp页面并没有取得用户名，就是演示一下。还有<div>可以换span，具体作用问美工吧。
接受ajax请求的action。
import org.apache.struts.action.*;
import javax.servlet.http.*;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.PrintWriter;
/**
* <p>Title:AjaxAction </p>
*/
public class AjaxAction extends Action {
public ActionForward execute(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws Exception {
PrintWriter out = response.getWriter();
out.print(1);//ajax取得都是字符的输出。如果数据量大的话，还可以用xml来发送和接受
return null;
}
}
struts-config.xml
<action type="test.whw.upload.AjaxAction" validate="false" scope="request" path="/ajax"/>
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如果是servlet
web.xml
<servlet>
<servlet-name>AjaxServlet </servlet-name>
<servlet-class>servlet.AjaxServlet </servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>AjaxServlet </servlet-name>
<url-pattern>/AjaxServlet .servlet</url-pattern>
</servlet-mapping>
AjaxServlet.java
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 AjaxServlet extends HttpServlet {
Logger log = Logger.getLogger(this.getClass());
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException,IOException {
response.setContentType("text/xml; charset=GBK");
PrintWriter out = response.getWriter();
out.print(2);
}
}
//Process the HTTP Post request
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
//Process the HTTP Put request
public void doPut(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
}
//Process the HTTP Delete request
public void doDelete(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
}
//Clean up resources
public void destroy() {
}
}
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如果是webwork
xwork.xml
<action name="ajax" class="com.whw.upload.action.webwork.AjaxAction" method="ajax"/>
AjaxAction.java
import java.io.PrintWriter;
public class AjexAlbumAction extends ActionSupport implements Action{
public void ajax()throws IOException {
PrintWriter pw = ServletActionContext.getResponse().getWriter();
ServletActionContext.getResponse().setContentType("text/html;charset=GBK");
pw.print(1);
pw.close();
}
}
本例子在winXPsp2、JB9、Eclipse3，j2sdk1.4.1 、Tomcat5、Tomcat4.1都能运行
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