ajax与json

1.ajax请求servlet(picnews.js)

		
		
		//1定义
  		var xmlHttp  = false;
  		
  		//2，创建
  		function createXmlHttp() {
  			if(window.ActiveXObject) {
  				xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
  			} else {
  				xmlHttp = new XMLHttpRequest();
  			}
  			
  		}
  		
  		function getData() {
  			createXmlHttp();
  			var  url = "servlet/FocusNewsServlet";
  			//打开异步请求
  			xmlHttp.open("get",url,"true");
  			
  			//监听异步请求状态
  			xmlHttp.onreadystatechange = callback;
  			
  			//发送异步请求
  			xmlHttp.send();
  			
  			
  		}
  		function callback(){
  			
  			if(xmlHttp.readyState == 4) {
  			
  			
  				var json = xmlHttp.responseText;
  				
  				
  				var res = eval('('+json+')');
  				
  				
  				
  				
	  			//for(var i in json)
 				// {
 				// alert("picId"+i+"="+res.list[i].picId);	//alert:imgUrl2=images/homead/2011060301.jpg
 				// }
 				
 				showFocus(res); 
	  			
  				
  			}
  		};
  		



	function showFocus(res)
	{
		var focus_width=280;
		var focus_height=180;
		var text_height=0;
		var swf_height=focus_height + 0;
		var pic1=res.list[2].picUrl;
		var pics="UploadImages/"+res.list[0].picUrl+"###UploadImages/"+res.list[1].picUrl+"###UploadImages/"+res.list[2].picUrl+"###UploadImages/"+res.list[3].picUrl+"###UploadImages/"+res.list[4].picUrl;
		var links=res.list[0].picLink+"###"+res.list[1].picLink+"###"+res.list[2].picLink+"###"+res.list[3].picLink+"###"+res.list[4].picLink;
		var texts=res.list[0].picText+"###"+res.list[1].picText+"###"+res.list[2].picText+"###"+res.list[3].picText+"###"+res.list[4].picText;
		var descripts=res.list[0].picDescripts+"###"+res.list[1].picDescripts+"###"+res.list[2].picDescripts+"###"+res.list[3].picDescripts+"###"+res.list[4].picDescripts+"";
		var fo = new SWFObject("swf/pix.swf", "_FocusObj", focus_width, swf_height, "7","F6F8FA");
		fo.addVariable("pics", pics);
		fo.addVariable("links", links);
		fo.addVariable("texts", texts); 
		fo.addVariable("descripts", descripts);
		fo.addVariable("borderwidth", focus_width);
		fo.addVariable("borderheight", focus_height);
		//fo.addVariable("textheight", text_height);
		fo.addVariable("border_color", "#666"); 
		//fo.addVariable("fontsize", "24"); 
		//fo.addVariable("fontcolor", "FFFFFF");
		fo.addVariable("is_border", "");
		fo.addVariable("is_text", "1");
		fo.addParam("wmode", "opaque");
		fo.write("FocusObj");
	}					
					
		getData();		

 

 

2.servlet返回json至前端

package com.bc.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import net.sf.json.JSONObject;

import com.bc.bean.AdminSheet;
import com.bc.dao.AdminOrclDAO;
import com.bc.dao.impl.daoImpl;

public class FocusNewsServlet extends HttpServlet {

	/**
	 * Constructor of the object.
	 */
	public FocusNewsServlet() {
		super();
	}

	/**
	 * Destruction of the servlet. <br>
	 */
	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}

	/**
	 * The doGet method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to get.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		
		response.setContentType("text/html;charset=UTF-8");
		PrintWriter out = response.getWriter();
		AdminOrclDAO dao=new AdminOrclDAO();
		List list=dao.findAllPicNewsSheet();
//		request.setAttribute("list", list);
//		RequestDispatcher requestDispatcher = request.getRequestDispatcher("/Admin/PortalFlashList.jsp");
//		requestDispatcher.forward(request,response);
//		String[] adName={};
//		for (int i = 0; i < list.size(); i++) {
//			System.out.println(((AdminSheet)(list.get(i))).getAdName());
//			out.print(((AdminSheet)(list.get(i))).getAdName());
//		}
		Map<String,Object> map = new HashMap<String,Object>();
//		map.put("a", "aaaa");
		map.put("list",list );
		JSONObject obj=JSONObject.fromObject(map);
		
//		out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
//		out.println("<HTML>");
//		out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");
//		out.println("  <BODY>");
//		out.print("${requestScope.}");
//		out.print(this.getClass());
//		out.println(", using the GET method");
//		out.println("  </BODY>");
//		out.println(list);
		out.println(obj);
		out.flush();
		out.close();
		
	}

	/**
	 * The doPost method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to post.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		out.println("...");
		out.flush();
		out.close();
	}

	/**
	 * Initialization of the servlet. <br>
	 *
	 * @throws ServletException if an error occurs
	 */
	public void init() throws ServletException {
		// Put your code here
	}

}

 

 

3.js解析json,取出数据

 

代码已在1,picnews.js内,解析方式:var res = eval('('+json+')');

 

取值json对象方式为:

 

res.list[i].picId