使用ajax请求时候:
响应的数据类型由ajax设置的接受数据方式决定：
responseText决定响应的数据类型是文本;
responseXML决定响应的数据类型xml文档。当返回xml文档时候Servlet一定要设置response.setContentType("text/xml;charset=utf-8");根据是否需要缓存，可以设置response.setHeader("Cache-control", "no-cache");
响应数据的格式由Servlet设置ContentType决定：
text/xml xml
text/html html
text/plain 文本
application/json json
下面是jsp--servlet 返回文本、xml文档、json、html的代码：
index.jsp
[html] view plain copy print ? <%@ 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 getXMLHttpRequest() { var xmlReq; if (window.XMLHttpRequest) {// code for IE7+, Firefox, Chrome, Opera, Safari xmlReq = new XMLHttpRequest(); } else {// code for IE6, IE5 xmlReq = new ActiveXObject("Microsoft.XMLHTTP"); } return xmlReq; } //返回文本数据测试 function ajaxText() { var oReq = getXMLHttpRequest(); oReq.open("POST", "TextServlet", true); oReq.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); //提交表单必须 oReq.send("name=我是文本&pwd=123"); oReq.onreadystatechange = function() { if (oReq.readyState == 4 && oReq.status == 200) { document.getElementById("myDiv").innerHTML = oReq.responseText; //responseText响应类型是文本 } } } //返回XML文档测试 function ajaxXML() { var oReq = getXMLHttpRequest(); oReq.open("POST", "HanderServlet", true); oReq.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); //提交表单必须 oReq.send("name=我是xml&pwd=111"); oReq.onreadystatechange = function() { if (oReq.readyState == 4 && oReq.status == 200) { var xmlObj=oReq.responseXML; //responseXML响应类型是XML文档 var names=xmlObj.documentElement.getElementsByTagName("name"); var name=names[0].firstChild.nodeValue; var pwds=xmlObj.documentElement.getElementsByTagName("pwd"); var pwd=pwds[0].firstChild.nodeValue; document.getElementById("myDiv").innerHTML=name+","+pwd; } } } //返回json文档测试 function ajaxJSON() { var oReq = getXMLHttpRequest(); oReq.open("POST", "JsonServlet", true); oReq.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); //提交表单必须 oReq.send("name=我是json&pwd=111"); oReq.onreadystatechange = function() { if (oReq.readyState == 4 && oReq.status == 200) { var resObj=oReq.responseText; //json字符串用文本形式接收 var jsonObj1=eval('('+resObj+')'); var name1=jsonObj1.name; var pwd1=jsonObj1.pwd; document.getElementById("myDiv").innerHTML=name1+","+pwd1; } } } //返回html function ajaxHTML() { var oReq = getXMLHttpRequest(); oReq.open("POST", "HtmlServlet", true); oReq.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); //提交表单必须 oReq.send("name=我是html&pwd=111"); oReq.onreadystatechange = function() { if (oReq.readyState == 4 && oReq.status == 200) { var resObj=oReq.responseText; //html用文本形式接收 document.getElementById("myDiv").innerHTML=resObj; } } } </script> </head> <body> <button onclick="ajaxText()">ajax请求文本</button> <button onclick="ajaxXML()">ajax请求XML文档</button> <button onclick="ajaxJSON()">ajax请求json字符串</button> <button onclick="ajaxHTML()">ajax请求html</button> <div id="myDiv"></div> </body> </html> 返回文本的Servlet:
[java] view plain copy print ? package com.ajax.test; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class TextServlet extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { System.out.println("in text"); request.setCharacterEncoding("utf-8"); String name=request.getParameter("name"); String pwd=request.getParameter("pwd"); System.out.println("name:"+name+",pwd:"+pwd); //返回文本数据 response.setContentType("text/plain;charset=utf-8"); ServletOutputStream outputStream = response.getOutputStream(); outputStream.write(name.getBytes("utf-8")); outputStream.write(pwd.getBytes("utf-8")); outputStream.flush(); outputStream.close(); } }
返回xml文档的Servlet
[java] view plain copy print ? package com.ajax.test; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class HanderServlet extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { System.out.println("in xml"); request.setCharacterEncoding("utf-8"); String name=request.getParameter("name"); String pwd=request.getParameter("pwd"); System.out.println("name:"+name+",pwd:"+pwd); //返回xml文档 response.setContentType("text/xml;charset=utf-8"); response.setHeader("Cache-control", "no-cache"); ServletOutputStream outputStream = response.getOutputStream(); StringBuffer sb=new StringBuffer(); sb.append("<?xml version='1.0' encoding='utf-8'?>"); sb.append("<user><name>"+name+"</name><pwd>"+pwd+"</pwd></user>"); outputStream.write(sb.toString().getBytes("utf-8")); outputStream.flush(); outputStream.close(); } }
返回json字符串的Servlet
[java] view plain copy print ? package com.ajax.test; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class JsonServlet extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { System.out.println("in json"); request.setCharacterEncoding("utf-8"); String name=request.getParameter("name"); String pwd=request.getParameter("pwd"); System.out.println("{'name':"+name+",'pwd':"+pwd+"}"); //返回json字符串数据 response.setContentType("application/json;charset=utf-8"); ServletOutputStream outputStream = response.getOutputStream(); String res="{'name':'"+name+"','pwd':'"+pwd+"'}"; //json字符串要写成"{'name':'tom'}"的形式，里面的key和value也要加''写成字符串的形式 outputStream.write(res.getBytes("utf-8")); outputStream.flush(); outputStream.close(); } }
返回html的Servlet
[java] view plain copy print ? package com.ajax.test; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class HtmlServlet extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { System.out.println("in html"); request.setCharacterEncoding("utf-8"); String name=request.getParameter("name"); String pwd=request.getParameter("pwd"); System.out.println("name:"+name+",pwd:"+pwd); //返回html文档 response.setContentType("text/html;charset=utf-8"); response.setHeader("Cache-control", "no-cache"); ServletOutputStream outputStream = response.getOutputStream(); String res="<font size='2' color='blue'>"+name+pwd+"</font>"; outputStream.write(res.getBytes("utf-8")); outputStream.flush(); outputStream.close(); } }
