048android初级篇之定时器Timer和TimerTask的详细使用

1. Timer()
Creates a new timer.
2. Timer(boolean isDaemon)
Creates a new timer whose associated thread may be specified to run as a daemon.
3. Timer(String name)
Creates a new timer whose associated thread has the specified name.
4. Timer(String name, boolean isDaemon)
Creates a new timer whose associated thread has the specified name, and may be specified to run as a daemon.

1. void     cancel()
    终止timer，丢弃所有任务的调度
    Terminates this timer, discarding any currently scheduled tasks.
2. int  purge()
    Removes all cancelled tasks from this timer's task queue.
    终止所有被取消的任务。
3. void     schedule(TimerTask task, Date time)
    Schedules the specified task for execution at the specified time.
    在指定的时间，运行此任务。
4. void     schedule(TimerTask task, Date firstTime, long period)
    Schedules the specified task for repeated fixed-delay execution, beginning at the specified time.
    在指定的时间Date firstTime运行此任务，之后每间隔long period时间运行一次。
5. void     schedule(TimerTask task, long delay)
    Schedules the specified task for execution after the specified delay.
    
6. void     schedule(TimerTask task, long delay, long period)
    Schedules the specified task for repeated fixed-delay execution, beginning after the specified delay.
7. void     scheduleAtFixedRate(TimerTask task, Date firstTime, long period)
    Schedules the specified task for repeated fixed-rate execution, beginning at the specified time.
8. void     scheduleAtFixedRate(TimerTask task, long delay, long period)
    Schedules the specified task for repeated fixed-rate execution, beginning after the specified delay.

这两个方法都是任务调度方法，他们之间区别是，schedule会保证任务的间隔是按照定义的period参数严格执行的，如果某一次调度时间比较长，那么后面的时间会顺延，保证调度间隔都是period,而scheduleAtFixedRate是严格按照调度时间来的，如果某次调度时间太长了，那么会通过缩短间隔的方式保证下一次调度在预定时间执行。举个栗子：你每个3秒调度一次，那么正常就是0,3,6,9s这样的时间，如果第二次调度花了2s的时间，如果是schedule，就会变成0,3+2,8,11这样的时间，保证间隔，而scheduleAtFixedRate就会变成0,3+2,6,9，压缩间隔，保证调度时间。

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

1. protected    TimerTask()
Creates a new timer task.
2. boolean  cancel()
Cancels this timer task.
3. abstract void    run()
The action to be performed by this timer task.
4. long     scheduledExecutionTime()
Returns the scheduled execution time of the most recent actual execution of this task.
？？返回下一次执行的时间  这一点不确认，运行测试代码，也不支持此解释，知道的同学指导下哈

/**
 * Created by Frank on 2016/8/23.
 */
public class TestTimerActivity extends Activity {

    private final String TAG ="TestTimerActivity";
    private TextView textviewCounter;
    private EditText editer;
    private Button mButtonStart;
    private Button mButtonStop;

    int mCounter =0;
    int mTime =1000;

    Timer mTimer;
    TimerTask mTimerTask;

    public final  int CODE_REFRESH = 1;

    Handler mHandler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what){
                case CODE_REFRESH:
                    textviewCounter.setText(""+mCounter++);
                    break;
            }
        }
    };
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN);
        setContentView(R.layout.test_timer);
        mTimer = new Timer();
        mTimerTask = new TimerTask() {
            @Override
            public void run() {
                if(textviewCounter!=null){
                   Message msg= mHandler.obtainMessage();
                    msg.what = CODE_REFRESH;
                    mHandler.sendMessage(msg);
                }
            }
        };

        mButtonStart =(Button) findViewById(R.id.start);
        mButtonStop =(Button) findViewById(R.id.stop);
        textviewCounter =(TextView) findViewById(R.id.textview_counter);
        editer =(EditText) findViewById(R.id.edit_text);

        mButtonStart.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(mTimerTask !=null){
                    mTimerTask.cancel();
                    Log.e(TAG,"time = "+mTimerTask.scheduledExecutionTime());
                }
                
                mTimer.purge();
                mTimerTask = new TimerTask() {
                    @Override
                    public void run() {
                        if(textviewCounter!=null){
                            Message msg= mHandler.obtainMessage();
                            msg.what = CODE_REFRESH;
                            mHandler.sendMessage(msg);
                        }
                    }
                };
                

                //mTime = Integer.parseInt(editer.getText().toString());
                mTime = 800;
                mTimer.schedule(mTimerTask,mTime,mTime);
                Log.e(TAG,"2time = "+mTimerTask.scheduledExecutionTime());

            }
        });

        mButtonStop.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(mTimerTask !=null){
                     mTimerTask.cancel();
                }
                mTimer.purge();
            }
        });
    }
}