servlet
1 //输出JSON格式的省份信息 2 @WebServlet("/ServletDemo1") 3 public class ServletDemo1 extends HttpServlet { 4 private static final long serialVersionUID = 1L; 5 6 7 public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { 8 response.setContentType("text/html;charset=UTF-8"); 9 PrintWriter out = response.getWriter(); 10 String str = "{name:‘山东省‘}"; 11 out.write(str); 12 }
json jsp中应用
eval函数用于转换成 json的文本 来让以后代码使用
1 <%@ page language="java" pageEncoding="utf-8"%> 2 3 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 4 <html> 5 <head> 6 <title>级联菜单</title> 7 <script type="text/javascript" src="./xmFile.js"> </script> 8 </head> 9 <body> 10 <select id="province" name="province"> 11 <option value="">请选择....</option> 12 </select> 13 <select id="city" name="city"> 14 <option value="">请选择.....</option> 15 </select> 16 <script type="text/javascript"> 17 window.onload=function(){ 18 var xhr = createXmlHttpRequest(); 19 xhr.onreadystatechange=function(){ 20 if(xhr.readyState==4){ 21 if(xhr.status==200||xhr.status==304){ 22 var data = xhr.responseText;//JSON数据，服务端是普通字符串返回的 23 var provinceJson = eval("("+data+")");//把普通的JSON字符串文本变成真正的JSON数据 24 25 var optionElement = document.createElement("option"); 26 optionElement.setAttribute("value",provinceJson.name); 27 var textNode = document.createTextNode(provinceJson.name); 28 optionElement.appendChild(textNode); 29 30 document.getElementById("province").appendChild(optionElement); 31 32 } 33 } 34 } 35 xhr.open("GET","${pageContext.request.contextPath}/ServletDemo1?time="+new Date().getTime()); 36 xhr.send(null); 37 } 38 function createXmlHttpRequest(){ 39 var xmlHttp; 40 try{ //Firefox, Opera 8.0+, Safari 41 xmlHttp=new XMLHttpRequest(); 42 }catch (e){ 43 try{ //Internet Explorer 44 xmlHttp=new ActiveXObject("Msxml2.XMLHTTP"); 45 }catch (e){ 46 try{ 47 xmlHttp=new ActiveXObject("Microsoft.XMLHTTP"); 48 }catch (e){} 49 } 50 } 51 return xmlHttp; 52 } 53 </script> 54 </body> 55 </html>