需求：
在web页面输入参数，通过Ajax将参数传入服务器，在服务器端进行接收
1、新建一个web项目，名称：Ajax
2、修改index.jsp
代码如下
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<%@ page contentType="text/html; charset=UTF-8" %>
<html xmlns="http://www.w3.org/1999/xhtml">
<html>
<head>
<title>www.mldnjava.cn，MLDN高端Java培训</title>
</head>
<body>
<script language="JavaScript">
var xmlHttp; //Ajax核心对象名称
function createXMLHttp() { //创建XMLHttpRequest核心对象
if (window.XMLHttpRequest) { //判断当前使用的浏览器类型
xmlHttp = new XMLHttpRequest(); //表示当前使用的是FireFox内核的浏览器
} else {
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
}
}
function checkUserid() {
createXMLHttp(); //建立xmlHttp核心对象
//设置一个请求，通过地址重写的方式将userid传递到JSP中
var userid = document.getElementById("userid").value;
xmlHttp.open("POST", "Ajax/CheckServlet?userid=" + userid);
xmlHttp.send(null); //发送请求，不传递任何参数
document.getElementById("msg").innerHTML = "传输结束";
}
</script>
用户ID:
<input type="text" id="userid">
<span id="msg"></span>
<br>
<button onclick="checkUserid()">传输</button>
</body>
</html>
3、创建CheckServlet.java
package com.ajax;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class CheckServlet extends HttpServlet {
<span style="white-space:pre"> </span>public void doGet(HttpServletRequest request,
<span style="white-space:pre"> </span>HttpServletResponse response) throws ServletException, IOException {
<span style="white-space:pre"> </span>this.doPost(request, response);
<span style="white-space:pre"> </span>}
<span style="white-space:pre"> </span>public void doPost(HttpServletRequest request,
<span style="white-space:pre"> </span>HttpServletResponse response) throws ServletException, IOException {
<span style="white-space:pre"> </span>request.setCharacterEncoding("UTF-8");
<span style="white-space:pre"> </span>response.setContentType("text/html"); // 设置回应的MIME
<span style="white-space:pre"> </span>String userid = request.getParameter("userid"); // 接收验证的userid
<span style="white-space:pre"> </span>System.out.println(userid);
<span style="white-space:pre"> </span>}
}
4、在web.xml中配置
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1"> <display-name>Ajax</display-name> <welcome-file-list> <welcome-file>index.html</welcome-file> <welcome-file>index.htm</welcome-file> <welcome-file>index.jsp</welcome-file> <welcome-file>default.html</welcome-file> <welcome-file>default.htm</welcome-file> <welcome-file>default.jsp</welcome-file> </welcome-file-list> <servlet> <servlet-name>CheckServlet</servlet-name> <servlet-class>com.ajax.CheckServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>CheckServlet</servlet-name> <url-pattern>/Ajax/CheckServlet</url-pattern> </servlet-mapping> </web-app>
这样就可以在后台接收到前端发送过来的参数了