访问Web服务的返回值

Question

I have a webservice which returns an arraylist of objects. I want to access this arraylist of objects in my android code. How do i do it? My webservice is

package com.chillum.first;

import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.QueryParam;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;

@Path("/hello")
public class ServerSide {

@GET
public ArrayList<myClass> Print (@QueryParam("param1") String key) throws IOException, InterruptedException
{
    Date date = new Date();
    SimpleDateFormat sdf = new SimpleDateFormat("MMddyyyyhmmss");
    String formattedDate = sdf.format(date);
    String command = "cmd /c start /wait C:\\python27\\tutorial\\check.bat "+key+" "+formattedDate;
    Process p=Runtime.getRuntime().exec(command);
    p.waitFor();
    myClass[] flipkart=new myClass[500];
    myClass[] amazon=new myClass[500];
    myClass[] myntra=new myClass[500];
    myClass[] jabong=new myClass[500];
    myClass[] shopclues=new myClass[500];
    myClass[] hs18=new myClass[500];
    myClass[] indiatimes=new myClass[500];
    myClass[] croma=new myClass[500];

    String xmlFileNames[]=new String[8];
    xmlFileNames[0]="C:/python27/tutorial/"+formattedDate+"flipkart.xml";
    xmlFileNames[1]="C:/python27/tutorial/"+formattedDate+"amazon.xml";
    xmlFileNames[2]="C:/python27/tutorial/"+formattedDate+"myntra.xml";
    xmlFileNames[3]="C:/python27/tutorial/"+formattedDate+"jabong.xml";
    xmlFileNames[4]="C:/python27/tutorial/"+formattedDate+"shopclues.xml";
    xmlFileNames[5]="C:/python27/tutorial/"+formattedDate+"hs18.xml";
    xmlFileNames[6]="C:/python27/tutorial/"+formattedDate+"indiatimes.xml";
    xmlFileNames[7]="C:/python27/tutorial/"+formattedDate+"croma.xml";

    String[] domain=new String[8];
    domain[0]="http://www.flipkart.com";
    domain[1]="";
    domain[2]="http://www.myntra.com";
    domain[3]="";
    domain[4]="http://www.shopclues.com";
    domain[5]="http://www.homeshop18.com";
    domain[6]="http://www.shopping.indiatimes.com";
    domain[7]="http://www.cromaretail.com/";


    try {
        random(flipkart, xmlFileNames[0], domain[0]);
        random(amazon, xmlFileNames[1], domain[1]);
        random(myntra, xmlFileNames[2], domain[2]);
        random(jabong, xmlFileNames[3], domain[3]);
        random(shopclues, xmlFileNames[4], domain[4]);
        random(hs18, xmlFileNames[5], domain[5]);
        random(indiatimes, xmlFileNames[6], domain[6]);
        random(croma, xmlFileNames[7], domain[7]);

    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    ArrayList<myClass> all= new ArrayList<myClass>();
    for(int i=0, j=0; i<50; i++, j++)
    {
        try
        {
            all.add(flipkart[i]);
            all.add(amazon[i]);
            all.add(myntra[i]);
            all.add(jabong[i]);
            all.add(shopclues[i]);
            all.add(hs18[i]);
            all.add(indiatimes[i]);
            all.add(croma[i]);
        }
        catch(NullPointerException npe)
        {
        }
            continue;
    }
    return all;
}
public static void random(myClass[] obj, String fileName, String domain) throws Exception
{
    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    DocumentBuilder builder = factory.newDocumentBuilder();
    try
    {
        Document document = builder.parse(new InputSource(new FileReader( new File(fileName))));
        NodeList title = document.getElementsByTagName("title");
        NodeList price = document.getElementsByTagName("price");
        NodeList link = document.getElementsByTagName("link");
        NodeList image = document.getElementsByTagName("image");
        for (int i = 0; i < title.getLength(); i++) {
            int objcount=0;
            NodeList titleChildList = title.item(i).getChildNodes();
            NodeList priceChildList = price.item(i).getChildNodes();
            NodeList linkChildList = link.item(i).getChildNodes();
            NodeList imageChildList = image.item(i).getChildNodes();
            for (int j = 0; j < titleChildList.getLength(); j++) {
                obj[objcount]=new myClass();
                Node titleChildNode = titleChildList.item(j);
                if ("value".equals(titleChildNode.getNodeName())) {

                    obj[objcount].title=titleChildList.item(j).getTextContent()
                            .trim();
                }
                Node priceChildNode = priceChildList.item(j);
                if ("value".equals(priceChildNode.getNodeName())) {
                    obj[objcount].price=priceChildList.item(j).getTextContent()
                            .trim();
                }   
                Node linkChildNode = linkChildList.item(j);
                if ("value".equals(linkChildNode.getNodeName())) {
                    obj[objcount].link=domain+linkChildList.item(j).getTextContent()
                        .trim();
                }
                Node imageChildNode = imageChildList.item(j);
                if ("value".equals(imageChildNode.getNodeName())) {
                    obj[objcount].image=imageChildList.item(j).getTextContent()
                        .trim();
                }
                objcount++;
            }
        }   
    }
    catch(NullPointerException npe) {
    }

}

}

And my java class which returns to android is

package com.example.chillum;

import android.net.http.AndroidHttpClient;

import com.example.chillum.Utils;

import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.util.EntityUtils;

import java.util.ArrayList;

public class HttpManager {

public static ArrayList<myClass> getdata(String uri)
{
    AndroidHttpClient client=AndroidHttpClient.newInstance("AndroidAgent");
    HttpGet request=new HttpGet(uri);
    HttpResponse response;
    try{
        response=client.execute(request);
        return //what?;
    }
    catch(Exception e)
    {
        e.printStackTrace();
        return null;
    }
    finally
    {
        client.close();
    }
}
}

What should i return such that i get the array list? This methods returns to an async task where the other operations are to be done with the arraylist. please help.

Answer 1

You can't transfer a Java Object from the server to the client using HTTP. HTTP uses basic ASCII text to transfer data (hence Hyper Text Transfer Protocol).

The workaround that needs to be used is using a standard markup language to encode the data you are sending from the server. The major ones that are used right now are JSON and XML.

JSON looks like this :

{ 
"company": Volkswagen,
"name": "Vento",
"price": 800000
}

And XML Looks like this :

<car>
<company>Volkswagen</company>
<name>Vento</name>
<price>800000</price>
</car>

In simple terms: You will have to convert the Object you want to send to JSON/XML before emitting to the client request. Then use a JSON decode function at the client side to get back the object.

There are quite a good number of tutorials to show how to use JSON/XML to transfer data between server and Android Activity.

Hope this helps.