一、普通服務
1 . 定義服務
package com.ysy.mythreaddemo;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
public class MyService extends Service {
public MyService () {
}
@Override
public void onCreate () {
super.onCreate ();
}
@Override
public int onStartCommand (Intent intent, int flags, int startId) {
return super.onStartCommand (intent, flags, startId);
}
@Override
public IBinder onBind (Intent intent) {
throw new UnsupportedOperationException ("Not yet implemented");
}
@Override
public void onDestroy () {
super.onDestroy ();
}
}
2 . 啟動和停止服務
- 啟動服務
Intent service = new Intent (this,MyService.class);
startService (service);
- 停止服務
stopService (service);
3 . 綁定和解綁服務、調用服務中的方法。
- 綁定服務前的準備
在服務中定義一個公共的繼承Binder類，并實現一個自定義的接口（為了調用服務中的方法）的MyBinder類，在服務的onBind()方法中創建MyBinder對象并返回。
public class MyBinder extends Binder implements IService{
@Override
public void startDownload () {
Log.d ("ysy","start download!");
}
@Override
public int getProgress () {
Log.d ("ysy","get progress!");
return 0;
}
}
@Override
public IBinder onBind (Intent intent) {
return new MyBinder ();
}
在活動中創建實現ServiceConnection接口的類，用于綁定服務。
public class MyConnection implements ServiceConnection{
@Override
public void onServiceConnected (ComponentName name, IBinder service) {
MyService.MyBinder mService = (MyService.MyBinder) service;
mService.startDownload ();
int progress = mService.getProgress ();
Log.d ("ysy","progress "+progress);
}
@Override
public void onServiceDisconnected (ComponentName name) {
}
}
- 綁定服務
conn = new MyConnection ();
Intent service = new Intent (this,MyService.class);
bindService (service,conn,BIND_AUTO_CREATE);
解綁服務
unbindService (conn);調用服務中的方法
@Override
public void onServiceConnected (ComponentName name, IBinder service) {
MyService.MyBinder mService = (MyService.MyBinder) service;
mService.startDownload ();
int progress = mService.getProgress ();
Log.d ("ysy","progress "+progress);
}
4 . 服務的幾個規則
- 服務可以被多次啟動，每次啟動都會執行onStartCommand()方法
- 服務可以多次綁定，但只會執行一次onBind()方法。
- 服務只能解綁一次，解綁多次會出錯。
- 服務的onCreate()方法只會在第一次啟動或者第一次綁定時調用。
- 服務的onDestory()方法只會在停止服務的時候，或者在未啟動但綁定狀態下，解綁時調用。
二、前臺服務
- 前臺服務與普通服務的區別是，前臺服務啟動起來之后，會在系統的狀態欄一直有個圖標顯示，下拉狀態之后會看到更詳細的信息。
- 前臺服務的定義與普通服務定義的不同是，前臺服務會在普通服務的onCreate()方法中添加以下代碼。
Intent intent = new Intent (this,MainActivity.class);
PendingIntent pi = PendingIntent.getActivity (this,0,intent,0);
Notification build = new NotificationCompat.Builder (this)
.setContentTitle ("this is title")
.setContentText ("this is content")
.setSmallIcon (R.mipmap.ic_launcher)
.setWhen (System.currentTimeMillis ())
.setContentIntent (pi)
.build ();
startForeground (1,build);
- 前臺服務的啟動與普通服務的啟動相同。
三、在服務中做耗時操作
- 服務是運行在主線程中的，android規定不能在主線程中做耗時操作。
- 使用IntentService可以在服務中做耗時操作，定義如下:
package com.ysy.mythreaddemo;
import android.app.IntentService;
import android.content.Context;
import android.content.Intent;
import android.util.Log;
/**
* An {@link IntentService} subclass for handling asynchronous task requests in
* a service on a separate handler thread.
* <p>
* TODO: Customize class - update intent actions, extra parameters and static
* helper methods.
*/
public class MyIntentService extends IntentService {
// TODO: Rename actions, choose action names that describe tasks that this
// IntentService can perform, e.g. ACTION_FETCH_NEW_ITEMS
private static final String ACTION_FOO = "com.ysy.mythreaddemo.action.FOO";
private static final String ACTION_BAZ = "com.ysy.mythreaddemo.action.BAZ";
// TODO: Rename parameters
private static final String EXTRA_PARAM1 = "com.ysy.mythreaddemo.extra.PARAM1";
private static final String EXTRA_PARAM2 = "com.ysy.mythreaddemo.extra.PARAM2";
public MyIntentService () {
super ("MyIntentService");
}
/**
* Starts this service to perform action Foo with the given parameters. If
* the service is already performing a task this action will be queued.
*
* @see IntentService
*/
// TODO: Customize helper method
public static void startActionFoo (Context context, String param1, String param2) {
Intent intent = new Intent (context, MyIntentService.class);
intent.setAction (ACTION_FOO);
intent.putExtra (EXTRA_PARAM1, param1);
intent.putExtra (EXTRA_PARAM2, param2);
context.startService (intent);
}
/**
* Starts this service to perform action Baz with the given parameters. If
* the service is already performing a task this action will be queued.
*
* @see IntentService
*/
// TODO: Customize helper method
public static void startActionBaz (Context context, String param1, String param2) {
Intent intent = new Intent (context, MyIntentService.class);
intent.setAction (ACTION_BAZ);
intent.putExtra (EXTRA_PARAM1, param1);
intent.putExtra (EXTRA_PARAM2, param2);
context.startService (intent);
}
@Override
protected void onHandleIntent (Intent intent) {
if (intent != null) {
final String action = intent.getAction ();
if (ACTION_FOO.equals (action)) {
final String param1 = intent.getStringExtra (EXTRA_PARAM1);
final String param2 = intent.getStringExtra (EXTRA_PARAM2);
handleActionFoo (param1, param2);
} else if (ACTION_BAZ.equals (action)) {
final String param1 = intent.getStringExtra (EXTRA_PARAM1);
final String param2 = intent.getStringExtra (EXTRA_PARAM2);
handleActionBaz (param1, param2);
}
}
Log.d ("ysy","Thread is "+Thread.currentThread ().getId ());
}
/**
* Handle action Foo in the provided background thread with the provided
* parameters.
*/
private void handleActionFoo (String param1, String param2) {
// TODO: Handle action Foo
throw new UnsupportedOperationException ("Not yet implemented");
}
/**
* Handle action Baz in the provided background thread with the provided
* parameters.
*/
private void handleActionBaz (String param1, String param2) {
// TODO: Handle action Baz
throw new UnsupportedOperationException ("Not yet implemented");
}
@Override
public void onDestroy () {
super.onDestroy ();
Log.d ("ysy","onDestroy");
}
}
- 可以將耗時操作放在MyIntentService的onHandleIntent ()方法中，這個方法中的代碼是運行在子線程中。
