Android中IntentService的使用

IntentService继承自Service，可以处理异步请求。IntentService和Service的区别在于，用户可把任务通过startService()方法把任务封装在Intent中交于IntentService处理。IntentService可以处理多个任务，只需要实现在onHandleIntent()方法中实现每个任务的处理逻辑即可（用户通过调用startService来提交任务）。
Service默认运行在主线程中的，而IntentService则会自动开启子线程来处理请求。同时，IntentService对请求的处理是串行的，即按照提交的先后顺序处理请求，即使某个请求是耗时任务，也只有在该任务结束之后才会处理下一个任务。Intent对任务的处理是通过Handler完成的。在所有任务处理完毕之后会自动停止，而Service需要程序员主动调用stopService()方法才会停止。

IntentService的简单实现

public class MyIntentService extends IntentService {

    //必须重写这个方法，否则Service启动时会出错
    public MyIntentService(){
        super("MyIntentService");
    }

    /**
     * Creates an IntentService.  Invoked by your subclass's constructor.
     *
     * @param name Used to name the worker thread, important only for debugging.
     */
    public MyIntentService(String name) {
        super(name);
    }

	/*
	*请求的处理
	*/
    @Override
    protected void onHandleIntent(@Nullable Intent intent) {
        Log.d(TAG, "onHandleIntent: current thread = " + Thread.currentThread().getId());

        String action = intent.getAction();
        Log.d(TAG, "action = " + action);

        switch (action){
            case "com.guohao.task1":
                try {
                    Thread.sleep(3000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                Log.d(TAG, "onHandleIntent: task1 finished !");
                break;

            case "com.guohao.task2":
                Log.d(TAG, "onHandleIntent: task2 finished !");
                break;
        }
    }


    @Override
    public void onCreate() {
        super.onCreate();
        Log.d(TAG, "onCreate: ");
    }

    @Override
    public void onStart(@Nullable Intent intent, int startId) {
        super.onStart(intent, startId);
        Log.d(TAG, "onStart: ");
    }

    @Override
    public int onStartCommand(@Nullable Intent intent, int flags, int startId) {
        Log.d(TAG, "onStartCommand: ");
        return super.onStartCommand(intent, flags, startId);
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        Log.d(TAG, "onDestroy: ");
    }

}

IntentService的启动（任务请求的发送）

@Override
    public void onClick(View v) {
        Log.d(TAG, "onClick: current thread = " + Thread.currentThread().getId());
        Intent intent;
        switch (v.getId()){

            case R.id.btn_start_work_1:
                Log.d(TAG, "onClick: ");
                intent = new Intent(this, MyIntentService.class);
                intent.setAction("com.guohao.task1");
                startService(intent);

                break;

            case R.id.btn_start_work_2:
                intent = new Intent(IntentServiceTestActivity.this, MyIntentService.class);
                intent.setAction("com.guohao.task2");
                startService(intent);
                break;


        }