初学Android,绑定本地Service并与之通信(五十九)

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如果Service和访问者之间需要进行方法调用或数据交换,则需要使用bindService()和unbindService()方法启动，关闭服务

BindService和Started Service都是Service，有什么地方不一样呢：
1. Started Service中使用StartService（）方法来进行方法的调用，调用者和服务之间没有联系，即使调用者退出了，服务依然在进行【onCreate()- >onStartCommand()->startService()->onDestroy()】，注意其中没有onStart()，主要是被onStartCommand()方法给取代了，onStart方法不推荐使用了。

2. BindService中使用bindService()方法来绑定服务，调用者和绑定者绑在一起，调用者一旦退出服务也就终止了【onCreate()->onBind()->onUnbind()->onDestroy()】。

定义服务类

class="language-java">package WangLi.Service.BindService;

import class="tags" href="/tags/ANDROID.html" title=android>android.app.Service;
import class="tags" href="/tags/ANDROID.html" title=android>android.content.Intent;
import class="tags" href="/tags/ANDROID.html" title=android>android.os.Binder;
import class="tags" href="/tags/ANDROID.html" title=android>android.os.IBinder;

public class BindService extends Service {
	private int count;
	private boolean quit;
	// 定义onBinder方法所返回的对象
    private MyBinder binder = new MyBinder();
	// 通过继承Binder来实现IBinder类
	public class MyBinder extends Binder {
		public int getCount()
		{
			//获取Service的运行状态:count
			return count;
		}
	}
    //必须实现的方法
	@Override
	public IBinder onBind(Intent arg0) {
		System.out.println("Service is Binded");
		//返回IBinder对象
		return binder;
	}

	//Service被创建时回调该方法
	@Override
	public void onCreate()
	{
		super.onCreate();
		System.out.println("Service is Created");
		//启动一条线程,动态地修改count状态值
		new Thread()
		{
			@Override
			public void run()
			{
				while(!quit)
				{
					try
					{
						Thread.sleep(1000);
					}
					catch(InterruptedException e)
					{
						
					}
					count++;
				}
			}
		}.start();
	}
	//Service断开连接时回调该方法
	@Override
	public boolean onUnbind(Intent intent)
	{
		System.out.println("Service is Unbinded");
		return true;
	}
	//Serice被关闭之前回调
	@Override
	public void onDestroy()
	{
		super.onDestroy();
		this.quit = true;
		System.out.println("Service is Destroyed");
	}
}

绑定，解除服务

class="language-java">package WangLi.Service.BindService;

import class="tags" href="/tags/ANDROID.html" title=android>android.app.Activity;
import class="tags" href="/tags/ANDROID.html" title=android>android.app.Service;
import class="tags" href="/tags/ANDROID.html" title=android>android.content.ComponentName;
import class="tags" href="/tags/ANDROID.html" title=android>android.content.Intent;
import class="tags" href="/tags/ANDROID.html" title=android>android.content.ServiceConnection;
import class="tags" href="/tags/ANDROID.html" title=android>android.os.Bundle;
import class="tags" href="/tags/ANDROID.html" title=android>android.os.IBinder;
import class="tags" href="/tags/ANDROID.html" title=android>android.view.View;
import class="tags" href="/tags/ANDROID.html" title=android>android.view.View.OnClickListener;
import class="tags" href="/tags/ANDROID.html" title=android>android.widget.Button;
import class="tags" href="/tags/ANDROID.html" title=android>android.widget.Toast;

public class MainActivity extends Activity {
	Button bind, unbind, getServiceStatus;
	// 保持所启动的Service的IBinder对象
	BindService.MyBinder binder;
	// 定义一个ServiceConnection对象
	private ServiceConnection conn = new ServiceConnection() {
		@Override
		public void onServiceConnected(ComponentName name, IBinder class="tags" href="/tags/SERVICE.html" title=service>service) {
			System.out.println("--Service Connected--");
			// 获取Service的onBind方法所返回的MyBinder对象
			binder = (BindService.MyBinder) class="tags" href="/tags/SERVICE.html" title=service>service;
		}

		@Override
		public void onServiceDisconnected(ComponentName arg0) {
			System.out.println("--Service Disconnected--");
		}
	};

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		// 获取程序界面中的start,stop,getServiceStatus按钮
		bind = (Button) findViewById(R.id.bind);
		unbind = (Button) findViewById(R.id.unbind);
		getServiceStatus = (Button) findViewById(R.id.getServiceStatus);
		// 创建启动Service的Intent
		final Intent intent = new Intent();
		// 为Intent设置Action属性
		intent.setAction("WangLi.Service.Bind_Service");
		bind.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View arg0) {
				// 绑定指定的Service
				bindService(intent, conn, Service.BIND_AUTO_CREATE);
			}
		});
		unbind.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				// 解除绑定Service
				unbindService(conn);
			}
		});
		getServiceStatus.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				// 获取并显示Service的count值
				Toast.makeText(MainActivity.this,
						"Service的count值为:" + binder.getCount(), 4000).show();
			}
		});
	}
}