使用IntentService与BroadcastReceiver实现后台服务(Android7.0可用）

IntentService的优点

IntentService会创建单独的线程处理所有的Intent请求，
会处理onHandleIntent方法实现的代码，
隐藏开发者无须处理多线程问题，
当所有请求处理完成后，IntentService会自动停止

Action的使用

Action其实就是一个字符串，可以起到一个标识的作用

BroadcastReceiver的使用

BroadcastReceiver本质是一个监听器，有自己的进程
重写onReceive方法即可，但是在该方法里面不要执行耗时的操作，否则会ANR
发送
    创建Intent
    设置Action
    putExtra
    send发送
接收
    实现onReceive方法
在AndroidManifest内增加配置
BroadcastReceiver
其他
    开机自动运行的Service

第一步

动态注册广播
broadcastReceiver = new MyReceiver();
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction("com.example.space.text2.action.MSGTEXT");
//这个Action的作用是当发送为该Action的广播时，
该MyReceiver类的onReceive方法将会接收到并处理
    registerReceiver(broadcastReceiver,intentFilter);

第二步

在Activity中添加一个UI组件，比如按钮
为按钮添加监听器
在该监听器内启动IntentService

Intent  intent = new Intent(FinsihActivity.this,TextIntentService.class);   
            intent.setAction("com.example.space.text2.action.MSGFINSIH");
//设置该Action以便IntentService接收到Intent，
判断是哪个Action,如果是这个Action话，就进行相应处理
intent.putExtra("finish","这是finishactivity发送的消息");
FinsihActivity.this.startService(intent);

第三步

添加一个IntentService.java类，可以使用Android Studio的自动生成
注释掉没有用的代码
但是一定要保留protected void onHandleIntent(Intent intent) 和
    public TextIntentService() {
        super("TextIntentService");
    }
方法
在protected void onHandleIntent(Intent intent) 方法中进行后台任务的处理即可

    protected void onHandleIntent(Intent intent) {
        if (intent != null) {
            final String action = intent.getAction();
            if (ACTION_MSGFINSIH.equals(action)) {
                String param1 = intent.getStringExtra("finish");
                Intent intent1 = new Intent(ACTION_MSGTEXT);
        //此处ACTION_MSGTEXT等于"com.example.space.text2.action.MSGTEXT"， 
        生成包含该Action的Intent后，就可以使用sendBroadcast发送广播了， 
        之后自己定义的MyReceiver类的onReceive方法将会接收到并处理
                intent1.putExtra("msg",param1+",IntentService收到并且广播了出去");
                sendBroadcast(intent1);

            }
        }
    }

第四步

在自己定义的MyReceiver类的onReceive方法将会接收到并处理收到的intent 

这个自己定义的MyReceiver类最好以内部类的形式写在使用该广播的Activity中， 
这样就可以使用该Activity的UI组件了， 
    即可实现把后台服务进程中的数据更新在UI线程中的UI组件中

    //内部类
    public class MyReceiver extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
         // TODO: This method is called when the BroadcastReceiver is receiving
            // an Intent broadcast.

         Toast.makeText(getApplicationContext(), intent.getStringExtra("msg"),  
               Toast.LENGTH_SHORT).show();


            //throw new UnsupportedOperationException("Not yet implemented");
            //注意，该句是自动生成的， 
                一定要注释掉，否则程序会崩溃重启，
                    无法显示出后台服务通过广播改变前台UI的效果
        }


    }

完整代码

第一个是Activity

public class FinsihActivity extends AppCompatActivity {

BroadcastReceiver broadcastReceiver;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_finsih);

    //第一步：注册广播，绑定广播和action
    try
    {
        broadcastReceiver = new MyReceiver();
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction("com.example.space.text2.action.MSGTEXT");
        registerReceiver(broadcastReceiver,intentFilter);
        Log.i("mss","registerReceiver(broadcastReceiver,intentFilter);");
    }
    catch (ParcelFormatException e)
    {
        Log.i("mss","catch");
    }


    Button button = (Button)super.findViewById(R.id.button2);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            //第二步：开始IntentService
            try
            {
                Intent  intent = new Intent(FinsihActivity.this,TextIntentService.class);
                Log.i("mss","Intent  intent = new Intent(FinsihActivity.this,TextIntentService.class)");
                intent.setAction("com.example.space.text2.action.MSGFINSIH");
                intent.putExtra("finish","这是finishactivity发送的消息");
                FinsihActivity.this.startService(intent);
                Log.i("mss","FinsihActivity.this.startService(intent);");
                Toast.makeText(getApplicationContext(), "startService(intent)", Toast.LENGTH_SHORT).show();
            }
            catch(ParcelFormatException e)
            {
                Log.i("mss","catch");
            }



        }
    });

}
//内部类
public class MyReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        // TODO: This method is called when the BroadcastReceiver is receiving
        // an Intent broadcast.

                //
        Toast.makeText(getApplicationContext(), intent.getStringExtra("msg"), Toast.LENGTH_SHORT).show();
//                    TextView textView = (TextView)FinsihActivity.super.findViewById(R.id.textView13);
//                    textView.setText(""+intent.getStringExtra("msg"));


        //throw new UnsupportedOperationException("Not yet implemented");
    }


}
}

第二个是IntentService

public class TextIntentService 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_MSGTEXT = "com.example.space.text2.action.MSGTEXT";
private static final String ACTION_MSGFINSIH = "com.example.space.text2.action.MSGFINSIH";
private static final String ACTION_BAZ = "com.example.space.text2.action.BAZ";

// TODO: Rename parameters

public TextIntentService() {
    super("TextIntentService");
}

//    /**
//     * 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, TextIntentService.class);
//        intent.setAction(ACTION_MSGTEXT);
//        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, TextIntentService.class);
//        intent.setAction(ACTION_BAZ);
//        intent.putExtra(EXTRA_PARAM1, param1);
//        intent.putExtra(EXTRA_PARAM2, param2);
//        context.startService(intent);
//    }

@Override
protected void onHandleIntent(Intent intent) {
    Log.i("mss","onHandleIntent");
    if (intent != null) {
        final String action = intent.getAction();
        if (ACTION_MSGFINSIH.equals(action)) {
            Log.i("mss","ACTION_MSGFINSIH.equals(action)");
            String param1 = intent.getStringExtra("finish");
            Log.i("mss","intent.getStringExtra(\"finish\") = "+param1);
            Intent intent1 = new Intent(ACTION_MSGTEXT);
            Log.i("mss","Intent intent1 = new Intent(ACTION_MSGTEXT);");
            Log.i("mss",ACTION_MSGTEXT);
            intent1.putExtra("msg",param1+",IntentService收到并且广播了出去");
            Log.i("mss","intent1.putExtra(\"msg\",param1+\",IntentService收到并且广播了出去\");");
            sendBroadcast(intent1);
            Log.i("mss","super.sendBroadcast(intent1);");

        }
    }
}

//    /**
//     * 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");
//    }
//    private void handleActionFinish(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");
//    }
}

第三个是AndroidManifest

<service
            android:name=".TextIntentService"
            android:exported="false"></service>
其中exported="false"的意思是防止其他应用访问该Service