服务的简单说明

一、前台服务与IntentService：

前台服务可以一直保持运行状态，而不会由于系统内存不足的原因导致被回收

service服务测试的准备代码

我们通过一个具体的案例来说明start与bind方式的service服务的生命周期的介绍。项目结果如下：

一、在MainActivity.java中做一些初始化工作，如下代码：

private final static String TAG = "MyIntentService";private MyIntentService.MyBinder binder;private ServiceConnection connection = new ServiceConnection() {    @Override    public void onServiceConnected(ComponentName name, IBinder service) {        binder = (MyIntentService.MyBinder) service;        binder.sayHello(name.getClassName());    }    @Override    public void onServiceDisconnected(ComponentName name) {        Log.i(TAG, "service disconnect: " + name.getClassName());    }};@Overrideprotected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);}

二、创建一个简单的IntentService服务类：MyIntentService

package com.example.linux.intentservicetest;import android.app.IntentService;import android.content.Intent;import android.os.Binder;import android.os.IBinder;import android.util.Log;public class MyIntentService extends IntentService {    private final static String TAG = "MyIntentService";    private MyBinder myBinder = new MyBinder();    class MyBinder extends Binder {        public void sayHello(String name) {            Log.i(TAG, "say hello method: " + name);        }        public void sayWorld(String name) {            Log.i(TAG, "say world method: " + name);        }    }    @Override    public IBinder onBind(Intent intent) {        return myBinder;    }    public MyIntentService() {        super("MyIntentService");        Log.i(TAG, "myintent service constructor.");    }    @Override    public void onCreate() {        Log.i(TAG, "on create.");        super.onCreate();    }    @Override    protected void onHandleIntent(Intent intent) {        Log.i(TAG, "handle intent: " + intent.getStringExtra("username") + ", thread: " + Thread.currentThread());    }    @Override    public void onDestroy() {        super.onDestroy();        Log.i(TAG, "on destroy.");    }    @Override    public int onStartCommand(Intent intent, int flags, int startId) {        Log.i(TAG, "on start command.");        return super.onStartCommand(intent, flags, startId);    }    @Override    public boolean onUnbind(Intent intent) {        //默认返回false        String username = intent.getStringExtra("username");        Log.i(TAG, "on unbind: " + super.onUnbind(intent) + ", username: " + username);        return true;    }    @Override    public void onRebind(Intent intent) {        Log.i(TAG, "on rebind");        super.onRebind(intent);    }}

三、创建一个简单的前台服务类：FrontService

package com.example.linux.intentservicetest;import android.app.Notification;import android.app.PendingIntent;import android.app.Service;import android.content.Intent;import android.os.IBinder;import android.util.Log;public class FrontService extends Service {    private final static String TAG = "MyIntentService";    public FrontService() {        Log.i(TAG, "front service constructor");    }    @Override    public IBinder onBind(Intent intent) {        return null;    }    @Override    public void onCreate() {        super.onCreate();        Notification.Builder builder = new Notification.Builder(this);        Intent intent = new Intent(this, MainActivity.class);        PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent,                PendingIntent.FLAG_CANCEL_CURRENT);        builder.setSmallIcon(R.mipmap.ic_launcher).setTicker("ticker");        builder.setWhen(System.currentTimeMillis()).setAutoCancel(true);        builder.setContentTitle("content title").setContentText("content text");        builder.setContentIntent(pendingIntent);        Notification notify = builder.getNotification();        notify.defaults = Notification.DEFAULT_ALL;        startForeground(10, notify);    }}

四、在AndroidManifest.xml中注册服务与活动：

Intent服务的使用

一、在MainActivity中创建方法，启动停止服务：

// 开启服务public void startService(View view) {    Intent intent = new Intent();    intent.putExtra("username", "linux");    intent.setClass(MainActivity.this, MyIntentService.class);    startService(intent);}// 停止服务public void stopService(View view) {    Intent intent = new Intent();    intent.setClass(MainActivity.this, MyIntentService.class);    stopService(intent);}

二、在MainActivity中创建方法，绑定解绑服务：

// 绑定服务public void bindService(View view) {    Intent intent = new Intent();    intent.setClass(MainActivity.this, MyIntentService.class);    intent.putExtra("username", "linux");    boolean isBind = bindService(intent, connection, Context.BIND_AUTO_CREATE);    Log.i(TAG, "bind service: " + isBind);}// 解绑服务public void unbindService(View view) {    Intent intent = new Intent();    intent.setClass(MainActivity.this, MyIntentService.class);    unbindService(connection);}

三、运行结果：

点击start：

03-25 08:01:53.460 8389-8389/? I/MyIntentService: myintent service constructor.03-25 08:01:53.460 8389-8389/? I/MyIntentService: on create.03-25 08:01:53.475 8389-8389/? I/MyIntentService: on start command.03-25 08:01:53.477 8389-8727/? I/MyIntentService: handle intent: linux, thread: Thread[IntentService[MyIntentService],5,main]03-25 08:01:53.478 8389-8389/? I/MyIntentService: on destroy.

点击stop：无输出

点击bind：

03-25 08:02:25.421 8389-8389/? I/MyIntentService: bind service: true03-25 08:02:25.422 8389-8389/? I/MyIntentService: myintent service constructor.03-25 08:02:25.422 8389-8389/? I/MyIntentService: on create.03-25 08:02:25.432 8389-8389/? I/MyIntentService: say hello method: com.example.linux.intentservicetest.MyIntentService

点击unbind：

03-25 08:02:28.486 8389-8389/? I/MyIntentService: on unbind: false, username: linux03-25 08:02:28.490 8389-8389/? I/MyIntentService: on destroy.

前台服务的使用

一、在MainActivity中创建方法，启动前台服务：

// 前台服务的使用public void frontService(View view) {    Intent intent = new Intent();    intent.setClass(MainActivity.this, FrontService.class);    startService(intent);}

二、运行结果：在手机的通知栏中

IntentService的原理分析

一、 intentService是继承Service的抽象方法：

public abstract class IntentService extends Service

二、 intentService包含的一些字段引用如下：

private volatile Looper mServiceLooper;private volatile ServiceHandler mServiceHandler;private String mName;private boolean mRedelivery;private final class ServiceHandler extends Handler {    public ServiceHandler(Looper looper) {        super(looper);    }    @Override    public void handleMessage(Message msg) {        onHandleIntent((Intent)msg.obj);        stopSelf(msg.arg1);    }}

二、和service一样在启动的时候，首先是执行构造方法，接着是onCreate方法，然后是onStartCommand方法，在onStartCommand中执行了onStart方法(执行流程在讲过)：

onCreate方法，开启了一个线程，并且得到Looper与初始化了一个Handler

@Overridepublic void onCreate() {    // TODO: It would be nice to have an option to hold a partial wakelock    // during processing, and to have a static startService(Context, Intent)    // method that would launch the service & hand off a wakelock.    super.onCreate();    HandlerThread thread = new HandlerThread("IntentService[" + mName + "]");    thread.start();    mServiceLooper = thread.getLooper();    mServiceHandler = new ServiceHandler(mServiceLooper);}

onStart方法，用上述的Handler发送信息

@Overridepublic void onStart(Intent intent, int startId) {    Message msg = mServiceHandler.obtainMessage();    msg.arg1 = startId;    msg.obj = intent;    mServiceHandler.sendMessage(msg);}

onStartCommand方法，调用onStart方法，发送信息

@Overridepublic int onStartCommand(Intent intent, int flags, int startId) {    onStart(intent, startId);    return mRedelivery ? START_REDELIVER_INTENT : START_NOT_STICKY;}

最后上述的Handler得到信息，调用handleMessage方法，其中有stopSelf(msg.arg1)方法，停止了服务：

三、这里附上service类的两个方法，源代码是android6.0的

在Service中的onStart方法已经被废弃了：

/** * @deprecated Implement {
    @link #onStartCommand(Intent, int, int)} instead.*/@Deprecatedpublic void onStart(Intent intent, int startId) {}

在onStartCommand的方法中

public int onStartCommand(Intent intent, int flags, int startId) {    onStart(intent, startId);    return mStartCompatibility ? START_STICKY_COMPATIBILITY : START_STICKY;}

友情链接

关于服务的生命周期与简单使用：（）

：访问密码 a840

转载于:https://www.cnblogs.com/huhx/p/intentService.html

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