原文地址:http://www.iteye.com/topic/1130452

Jsonp(JSON with Padding)是资料格式 json 的一种“使用模式”,可以让网页从别的网域获取资料。

关于Jsonp更详细的资料请参考http://baike.baidu.com/view/2131174.htm,下面给出例子:

一.客户端

<!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" src="resource/js/jquery-1.7.2.js"></script>
    </head>
    <script type="text/javascript">
        $(function(){
            /*//简写形式,效果相同
            $.getJSON("http://app.example.com/base/json.do?sid=1494&busiId=101&jsonpCallback=?",
            function(data){$("#showcontent").text("Result:"+data.result)});*/
                $.ajax({
                    type : "get",
                    async:false,
                    url : "http://app.example.com/base/json.do?sid=1494&busiId=101",
                    dataType : "jsonp",//数据类型为jsonp
                    jsonp: "jsonpCallback",//服务端用于接收callback调用的function名的参数
                    success : function(data){
                        $("#showcontent").text("Result:"+data.result)
                    },
                    error:function(){
                        alert('fail');
                    }
                });
            });
    </script>
    <body>
        <div id="showcontent">Result:</div>
    </body>
</html>

二.服务器端

import java.io.IOException;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import net.sf.json.JSONObject;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class ExchangeJsonController {
    @RequestMapping("/base/json.do")
    public void exchangeJson(HttpServletRequest request,HttpServletResponse response) {
        try {
            response.setContentType(text/plain);
            response.setHeader("Pragma", "No-cache");
            response.setHeader("Cache-Control", "no-cache");
            response.setDateHeader("Expires", 0);
            Map<String,String> map = new HashMap<String,String>();
            map.put("result", "content");
            PrintWriter out = response.getWriter();
            JSONObject resultJSON = JSONObject.fromObject(map); //根据需要拼装json
            String jsonpCallback = request.getParameter("jsonpCallback");//客户端请求参数
            out.println(jsonpCallback+"("+resultJSON.toString(1,1)+")");//返回jsonp格式数据
            out.flush();
            out.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

原文地址:http://www.iteye.com/topic/1130452