JSON AJAX

JavaScript  Json http://www.dreamdu.com/blog/2008/10/19/json_in_javascript/

JSON :http://www.json.org/json-zh.html

 

<script type="  text/javascript  " src="js/json2.js  "></script>
<script type = "text/javascript">
var xmlHttp;
/*创建XMLHttpRequest对象 兼容Firefox，Ie浏览器*/
function createXMLHttpRequest(){
     if(window.ActiveXObject){
        xmlHttp = new  ActiveXObject( " Microsoft.XMLHTTP " );
    }  
     else if(window.XMLHttpRequest){
        xmlHttp = new XMLHttpRequest();
    }
}
/*发出Ajax请求并调用处理函数*/    
function  doJSON()  {
    var car = getCarObject();
     // Use the JSON JavaScript library to stringify the Car object
     var  carAsJSON  =  JSON.stringify(car);
    alert( " Car object as JSON:\n  "   +  carAsJSON + " type "+typeof carAsJSON);
    var  url  =   "JSONExample.json";
   
    createXMLHttpRequest();
    xmlHttp.open("POST" , url,  true);
    xmlHttp.onreadystatechange  =  handleStateChange;
    xmlHttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded");    
    xmlHttp.send(carAsJSON);
}
/*判断XMLHttpRequest对象的返回状态*/    
function  handleStateChange()  {
     if (xmlHttp.readyState  ==   4 )  {
         if (xmlHttp.status  ==   200 )  {
            parseResults();
        }
    }
}
/*处理从服务器返回的结果*/
function  parseResults()  {
     
     var result = xmlHttp.responseText;
     alert(result +" before JSON.parse(String) type "+typeof result);
     var resultObj = JSON.parse(result);
     alert(resultObj.name +" "+resultObj.height+" after JSON.parse(String) type  "+typeof resultObj);
     
     var  responseDiv  =  document.getElementById("serverResponse");
     if (responseDiv.hasChildNodes())  {
        responseDiv.removeChild(responseDiv.childNodes[ 0 ]);
    }
    var  responseText  =  document.createTextNode(xmlHttp.responseText);
    
    responseDiv.appendChild(responseText);
}
/*获得一个Car对象*/
function getCarObject(){
     return new Car("Dodge","Coronet R/T",1968,"yellow");
}
/*Car对象*/
function  Car(make, model, year, color)  {
     this.make  =  make;
     this.model  =  model;
     this.year  =  year;
     this.color  =  color;
}

</script>

   
<br/><br/>  
<form action="#">  
<input type="button" value="Click here to send JSON data to the server" onclick="doJSON();"/>  
</form>  

<h2>Server Response:</h2>  
<div id="serverResponse"></div>  

package com.nstars;

import java.io.BufferedReader;
import java.io.IOException;

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

import org.json.JSONException;
import org.json.JSONObject;

public class JSONExample extends HttpServlet {
	public  void doGet(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		doPost(request,response);
	}
	/*响应Post请求*/
	public void doPost(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		
		String json = readJSONStringFromRequestBody(request);

		// Use the JSON-Java binding library to create a JSON object in Java
		JSONObject jsonObject = null;
		try {
			jsonObject = new JSONObject(json);
		} catch (Exception e) {
			e.printStackTrace();
		}

		String responseText = "";
		try {
			responseText = " You have a  " + jsonObject.getInt("year")
					+ "   " + jsonObject.getString("make") + "   "
					+ jsonObject.getString("model") + "   " + "  that is  "
					+ jsonObject.getString("color") + "  in color. ";
		} catch (JSONException e) {
			e.printStackTrace();
		}
		
		JSONObject jsonObj = new JSONObject();
		try {
			jsonObj.putOnce("name", "边苏涛");
			jsonObj.put("height", 176);
		} catch (JSONException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		response.setContentType("text/xml");
		response.setCharacterEncoding("UTF-8");
		response.getWriter().print(jsonObj);
	}
	/*从request对象中读取JSON对象字符串*/
	private String readJSONStringFromRequestBody(HttpServletRequest request) {
		StringBuffer json = new StringBuffer();
		String line = null;
		try {
			BufferedReader reader = request.getReader();
			while ((line = reader.readLine()) != null) {
				json.append(line);
			}
		} catch (Exception e) {
			System.out.println(" Error reading JSON string:  " + e.toString());
		}
		return json.toString();
	}
}