如何使用JSP将JSON数据发送到服务器并获取JSON / XML作为响应

Question

I am a beginner for web application. I created a dynamic web project using java EE on glassfish server. Now I want to let client send data using json to server and receive data from server using json or xml. By searching online, I am now clear with how to program on server side. Now I use ajax to send json data. However, maybe it's to easy to code on the server, I can't find any code related to server. My server side should use JSP to read the json data, using a bean(finished) to generate some data and send the data back. Here is the code and I don't where is the problem. Can anyone give any advice to me? your help means a lot for me!

this is the ajax code on the client side. I sent two input number from a form

$(function() {
    $("#myform").submit(function() {
        var lat = $("#num1").val();
        var lon = $("#num2").val();
        alert("form");

        if (num1 == '' || num2 == '') {
            $('.success').fadeOut(200).hide();
            $('.error').fadeOut(200).show();
        } else {
            $.ajax({
                type : "POST",
                url : "marker.jsp",
                contenttype : 'application/json; charset=utf-8',
                data : {
                    "num1" : "wtf",
                    "num2" : $("#num2").val(),
                },

                success : function(msg) {
                    $('.success').fadeIn(200).show();
                    $('.error').fadeOut(200).hide();
                    alert(msg);

                }
            });
        }

        return false;
    });
});

but after I switch to the jsp page, I only found two null values displayed, here's the code on the server, I planned to send xml at the beginning and I am not sure whether the request.getParameter can work and how to send back these xml data or using json format to send the data back. Help!

<?xml version="1.0" encoding="UTF-8"?>
<%@ page contentType="text/xml" %>
<%@ page             import="javax.naming.InitialContext,net.roseindia.ejb3.stateless.*,javax.ejb.EJB,java.util.*"%>

<%
        try {

            String s1 = request.getParameter("num1");
            String s2 = request.getParameter("num2");
    %>
            <%=s1%>
            <%=s1%>

    <%
            if (s1 != null && s2 != null) {
                List<String> textdatas = cal.GetTextResults(s1, s2);

                for (String textdata : textdatas) {

                String textLocation= "("+textdata.split("\\t",2)[0]+")";
                System.out.println(textLocation);
    %>
    <text>
        <location><%=textLocation%></location>
        <event> <%=textdata.split("\\t",2)[1]%></event>
    </text>
    <%
                }

                List<String> images = cal.getImage();

                for(String image: images){
                System.out.println(image);
    %>          
    <image>
        <imglocation><%=image.split("\\t",2)[0]%></imglocation>>
        <path><%=image.split("\\t",2)[0]%></path>
    </image>



    <%          
            }
            }
        }// end of try
        catch (Exception e) {
            e.printStackTrace();
            //result = "Not valid";
        }
    %>

Answer 1

If you are not using any MVC framework I suggest you to adopt one. It doesn't seem that rendering an XML/JSON from a JSP is a good/easy practice. Its not difficult to see that your code its getting too cumbersome... not to say that it might not be valid code.

I suggest that you adopt a MVC framework - I use VRaptor which is quite a good and simple one, allows you to develop RESTful web apps without even being aware of it. Make sure to check this one minute guide !!! This framework by encapsulating ThoughWorks XStream Framework makes it dead simple to accomplish your task. Take a look at what would be needed to respond to a request with a JSON object:

    import static br.com.caelum.vraptor.view.Results.*;

    @Resource
    public class ClientsController {

    private final Result result;
    private final ClientDao dao;

    //result and dao parameters gets inject by VRaptor that
    //by its turn lets you chose which Dependency Injection framework
    //you wouldd like to be using with - pretty much as a plugin
    public ClientsController(Result result, ClientDao dao) {
        this.result = result;
        this.dao = dao;
    }

    @Get("/client/json")
    public void loadJson(MyParam param) {
        result.use(json()).from(dao.getClient(param.id)).serialize();
    }

    @Get("/client/xml")
    public void loadXml(MyParam param) { 
        result.use(xml()).from(dao.getClient(param.id)).serialize();
    }
}

Note that Vraptor deserializes MyParam object from JSON and also injects it to your controller action request arrives!

This example was taken from this page !