半期考试 之 多线程

Posted 2022-01-10 春招进大厂的梦想家

半期考试 之 多线程1

要求：

• 实现一个计时器，点击“启动”按钮后，计时器开始运行；
• 点击“记录”按钮，下方textView记录当前计时器的时长；
• 点击“定时器”按钮，启动一个三秒钟的计时器，三秒后TextView显示“三秒钟到了”
• 要求用android 多线程来实现

xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity" >

    <TextView
        android:id="@+id/activity_main_tvText"
        android:layout_width="match_parent"
        android:layout_height="64dp"
        android:gravity="center_horizontal|center_vertical"
        android:text="TextView"
        android:textSize="20dp"
        android:textStyle="bold" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button
            android:id="@+id/activity_main_bnStartOrStop"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="启动" />

        <Button
            android:id="@+id/activity_main_bnRecord"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="记录" />

        <Button
            android:id="@+id/activity_main_bnTimer"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="定时器" />
    </LinearLayout>
 
    <TextView
        android:id="@+id/activity_main_tvResult"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:padding="10dp"
        android:text="0：0.7"
        android:textSize="18dp" />
</LinearLayout>

java

public class MainActivity extends AppCompatActivity implements View.OnClickListener 
    //布局中的UI组件
    private TextView tvText;
    private TextView tvRecord;
    private Button bnStartOrStop;
    private Button bnRecord;
    private Button bnTimer;
    private Button bnAsyncTask;

    //定义时间：分钟，秒，厘秒
    private int Minute = 0;
    private int Second = 0;
    private int CentiSecond = 0;

    //定义Handler对象接收处理UI线程相关数据和组件
    final Handler handler = new Handler() 
        @Override
        public void handleMessage(Message msg) 
            // TODO Auto-generated method stub
            super.handleMessage(msg);
            //获取传递过来的Bundle数据
            Bundle bundle = msg.getData();
            int Counter = bundle.getInt("Counter", 0);
            //根据msg.what判断处理什么类型的数据
            switch (msg.what) 
                case 1:
                    Minute = Counter / 6000;
                    Second = Counter % 6000 / 100;
                    CentiSecond = Counter % 6000 % 100;
                    tvText.setText(String.format("%02d:%02d.%02d", Minute, Second, CentiSecond));
                    break;
                case 3:
                    tvText.setText("定时3秒我成功的启动了哦");
                    break;
            
        
    ;

    //定义多线程内部类实现一个秒表的数据更新
    private class StopwatchThread extends Thread 
        //标志位：启动停止线程运行：通过标志位来结束线程运行能保证数据的完整性
        private boolean isFlag = false;
        private Bundle data;
        private Message msg;

        public StopwatchThread() 
            isFlag = true;
            data = new Bundle();
        

        @Override
        public void run() 
            int Counter = 0;
            while (isFlag) 
                try 
                    data.putInt("Counter", Counter);
                    msg = new Message();
                    //指定从哪一个线程向UI线程发送消息
                    msg.what = 1;
                    msg.setData(data);
                    //向handle对象发送消息
                    handler.sendMessage(msg);
                    //休眠
                    Thread.sleep(10);
                    //计数器加1
                    Counter++;
                 catch (Exception ex) 

                
            
        

        //此方法能保证run里面的代码执行完成
        public void Stop() 
            isFlag = false;
        
    

    //定义Timer对象
    private final Timer timer = new Timer();
    //定义TimerTask的引用变量
    private TimerTask task;

    @Override
    protected void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //关联布局文件中的组件并设置相应按钮的监听事件
        tvText = findViewById(R.id.activity_main_tvText);
        tvRecord = findViewById(R.id.activity_main_tvResult);

        bnStartOrStop = findViewById(R.id.activity_main_bnStartOrStop);
        bnStartOrStop.setOnClickListener(this);

        bnRecord = findViewById(R.id.activity_main_bnRecord);
        bnRecord.setOnClickListener(this);

        bnTimer = findViewById(R.id.activity_main_bnTimer);
        bnTimer.setOnClickListener(this);

        bnAsyncTask = findViewById(R.id.activity_main_bnAsyncTask);
        bnAsyncTask.setOnClickListener(this);
    

    @Override
    public void onClick(View v) 
        switch (v.getId()) 
            case R.id.activity_main_bnStartOrStop:
                StartOrStop();
                break;
            case R.id.activity_main_bnRecord:
                //计数输出当时获取到的时间
                String strRecord = tvRecord.getText().toString();
                strRecord += String.format("%02d:%02d.%02d", Minute, Second, CentiSecond) + "\\r\\n";
                tvRecord.setText(strRecord);
                break;
            case R.id.activity_main_bnTimer:
                TimerStart();
                break;
        
    

    //定义一个bool值判断当前显示是否在运行状态
    private boolean isRunning = false;
    //定义一个子线程类的引用变量
    private StopwatchThread swThread;

    private void StartOrStop() 
        //启动或者停止
        if (!isRunning) 
            //如果当前线程不是在运行状态，则实例化子线程类对象
            swThread = new StopwatchThread();
            //调用start启动线程
            swThread.start();
            //将标志位置为true表示在运行状态
            isRunning = true;
            tvRecord.setText("");
            bnStartOrStop.setText("停止");
         else 
            //如果在运行状态则调用子类对象的Stop方法停止线程
            swThread.Stop();
            //将标志位置为true表示在停止状态
            isRunning = false;
            bnStartOrStop.setText("启动");
        
    

    private void TimerStart() 
        //定时器启动
        if (isRunning) 
            swThread.Stop();
            isRunning = false;
            bnStartOrStop.setText("启动");
        
        tvText.setText("3后秒启动");
        task = new TimerTask() 
            @Override
            public void run() 
                Message message = new Message();
                message.what = 3;
                handler.sendMessage(message);
            
        ;
        timer.schedule(task, 3000);
    

运行截图：