传递数据的一个更好的办法是直接将活动绑定到服务上，这样活动可以直接用服务的任何公共成员和方法。

活动

package com.example.androidtest;

import java.net.MalformedURLException;
import java.net.URL;

import android.app.Activity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.util.Log;
import android.view.View;
import android.widget.Toast;

public class ServicesActivity2 extends Activity {

	MyService2 serviceBinder;
	Intent i;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_services);
	}
	
	public void startService(View view){
		i = new Intent(ServicesActivity2.this, MyService2.class);
		bindService(i, connection, Context.BIND_AUTO_CREATE);
	}
	
	public void stopService(View view){
		stopService(new Intent(ServicesActivity2.this, MyService2.class));
	}
	
	//监控服务连接状态
	private ServiceConnection connection = new ServiceConnection(){
		//连接成功
		@Override
		public void onServiceConnected(ComponentName name, IBinder service) {
			// TODO Auto-generated method stub
			Toast.makeText(ServicesActivity2.this, "Service onServiceConnected", Toast.LENGTH_SHORT).show();
			
			serviceBinder = ((MyService2.MyBinder)service).getService();
			try {
				URL[] urls = new URL[] {
						new URL("http://www.amazon.com/somefile.pdf"),
						new URL("http://www.wrox.com/somefile.pdf"),
						new URL("http://www.google.com/somefile.pdf"),
						new URL("http://www.learn.com/somefile.pdf")	
				};
				serviceBinder.urls = urls;
			}catch(MalformedURLException e){
				Log.d("AndroidTest", e.getMessage());
			}
			startService(i);
		}
		//连接断开
		@Override
		public void onServiceDisconnected(ComponentName name) {
			// TODO Auto-generated method stub
			Toast.makeText(ServicesActivity2.this, "Service onServiceDisconnected", Toast.LENGTH_SHORT).show();
			
			serviceBinder = null;
		}
		
	};
}

服务

package com.example.androidtest;

import java.net.URL;

import android.app.Service;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Binder;
import android.os.IBinder;
import android.util.Log;
import android.widget.Toast;

public class MyService2 extends Service {
	
	URL[] urls;
	private final IBinder binder = new MyBinder();
	
	//为了将活动绑定到一个服务，必须首先在服务中声明一个扩展Binder类的内部类。
	public class MyBinder extends Binder {
		MyService2 getService(){
			return MyService2.this;
		}
	}

	@Override
	public IBinder onBind(Intent intent) {
		// TODO Auto-generated method stub
		return binder;
	}
	
	@Override
	public int onStartCommand(Intent intent, int flags, int startId){
		Toast.makeText(this, "Service Started", Toast.LENGTH_LONG).show();
		new DoBackgroundTask().execute(urls);
		return START_STICKY;
	}

	@Override
	public void onDestroy(){
		super.onDestroy();
		Toast.makeText(this, "Service Destroyed", Toast.LENGTH_LONG).show();
	}
	
	private int DownLoadFile(URL url)
	{
		try{
			Thread.sleep(5000);//模拟文件下载
		}catch(InterruptedException e){
			Log.d("AndroidTest", e.getMessage());
		}
		return 100;//文件大小
	}
	
	private class DoBackgroundTask extends AsyncTask<URL, Integer, Long>
	{
		/**
		 * 这个方法用于放置需要长时间运行的代码并在后台线程中执行。
		 * @param	progress	参数类型(Integer)由AsyncTask<>的第1个泛型参数类型定义
		 * @return				返回类型(Long)由AsyncTask<>的第3个泛型参数类型定义
		 */
		@Override
		protected Long doInBackground(URL... urls) {
			int count = urls.length;
			long totalBytesDownloaded = 0;
			for (int i=0; i<count; i++) {
				totalBytesDownloaded += DownLoadFile(urls[i]);
				//报告进度
				publishProgress((int) (((i+1)/(float)count)*100));
			}
			return totalBytesDownloaded;
		}
		
		/**
		 * 这一方法在UI线程中启动并在调用publishProgress()方法时调用。
		 * @param	progress	参数类型(Integer)由AsyncTask<>的第2个泛型参数类型定义
		 */
		protected void onProgressUpdate(Integer... progress)
		{
			String percent = String.valueOf(progress[0]) + "% downloaded";
			Log.d("AndroidTest", percent);
			Toast.makeText(getBaseContext(), percent, Toast.LENGTH_SHORT).show();
		}
		
		/**
		 * 这一方法在UI线程中启动并在doInBackground()方法执行完毕后调用。
		 * @param	result	参数类型(Long)由AsyncTask<>的第3个泛型参数类型定义
		 */
		protected void onPostExecute(Long result)
		{
			String str = "Downloaded "+result+" bytes";
			Toast.makeText(getBaseContext(), str, Toast.LENGTH_SHORT).show();
			//注意: 当后台线程执行完毕时，需要手动调用stopSelf()方法来停止服务
			//stopSelf()方法相当于调用stopService()方法来停止服务。
			stopSelf();
		}
	}
}