Android入门：通过JSON数据与服务器进行通信

package org.xiazdong.servlet;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

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

import org.json.JSONStringer;
import org.xiazdong.domain.Person;


@WebServlet("/ListServlet")
public class ListServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		doPost(request,response);
	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		List<Person> list = new ArrayList<Person>();
		for(int i=0;i<4;i++){
			Person person = new Person(i,"xiazdong-"+i,20+i);
			list.add(person);
		}
		//将List<Person>组织成JSON字符串
		JSONStringer stringer = new JSONStringer();
		try{
			stringer.array();
			for(Person person:list){
				stringer.object().key("id").value(person.getId()).key("name").value(person.getName()).key("age").value(person.getAge()).endObject();
			}
			stringer.endArray();
		}
		catch(Exception e){}
		response.getOutputStream().write(stringer.toString().getBytes("UTF-8"));
		response.setContentType("text/json; charset=UTF-8");  //JSON的类型为text/json
	}

}

package org.xiazdong.personlist;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.json.JSONArray;
import org.json.JSONObject;
import org.xiazdong.domain.Person;
import org.xmlpull.v1.XmlPullParser;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.util.Xml;
import android.widget.ListView;
import android.widget.SimpleAdapter;

public class MainActivity extends Activity {
	private ListView listView;

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		listView = (ListView) this.findViewById(R.id.listview);
		List<Person> persons = null;
		try {
			persons = getJSONData();
		} catch (Exception e) {
			e.printStackTrace();
		}
		List<Map<String, Object>> maps = new ArrayList<Map<String, Object>>();
		for (Person person : persons) {
			HashMap<String, Object> map = new HashMap<String, Object>();
			map.put("id", person.getId());
			map.put("name", person.getName());
			map.put("age", person.getAge());
			maps.add(map);
		}
		SimpleAdapter adapter = new SimpleAdapter(this, maps, R.layout.item,
				new String[] { "id", "name", "age" }, new int[] { R.id.id,
						R.id.name, R.id.age });
		listView.setAdapter(adapter);
	}

	//读取JSON数据并转为List<Person>
	private List<Person> getJSONData() throws Exception {
		List<Person> persons = new ArrayList<Person>();
		URL url = new URL("http://192.168.0.103:8080/Server/ListServlet");
		HttpURLConnection conn = (HttpURLConnection) url.openConnection();
		conn.setRequestMethod("GET");
		if (conn.getResponseCode() == 200) {
			InputStream in = conn.getInputStream();
			persons = parseJSON(in);
		}
		return persons;

	}
	private List<Person> parseJSON(InputStream in)throws Exception{
		List<Person> persons = new ArrayList<Person>();
		Person person = null;
		String str = read(in);
		JSONArray array = new JSONArray(str);
		int length = array.length();
		for(int i=0;i<length;i++){
			JSONObject object = array.getJSONObject(i);
			person = new Person(object.getInt("id"), object.getString("name"), object.getInt("age"));
			persons.add(person);
		}
		return persons;
	}
	private String read(InputStream in) throws IOException {
		byte[] data;
		ByteArrayOutputStream bout = new ByteArrayOutputStream();
		byte[]buf = new byte[1024];
		int len = 0;
		while((len = in.read(buf))!=-1){
			bout.write(buf, 0, len);
		}
		data = bout.toByteArray();
		return new String(data,"UTF-8");
	}
}