5.实战之打地鼠案例（巩固Handler的使用）

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1.实现效果

如下图所示：

2.代码实现

新建一个名为DiglettDemo的项目，activity_main.xml代码如下：

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

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="80dp"
        android:layout_height="80dp"
        android:src="@drawable/diglett"
        android:visibility="gone" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="45dp"
        android:text="点击开始" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="20dp"
        android:textColor="#ff0000"
        android:textSize="20sp" />
</RelativeLayout>

MainActivity.class代码如下：

public class MainActivity extends AppCompatActivity implements View.OnClickListener, View.OnTouchListener {

    public static final int CODE = 999;
    public static final int RANDOM_NUMBER = 500;
    private TextView mTextView;
    private Button mButton;
    private ImageView mImageView;

    /**
     * 定义地鼠的位置
     */
    public int[][] mPosition = new int[][]{
            {342, 180}, {432, 880}, {521, 256}, {429, 780},
            {456, 976}, {145, 665}, {123, 678}, {564, 567},
    };

    private int mTotalCount, mSuccessCount = 0;
    public static final int MAX_COUNT = 10;

    private MyHandler mMyHandler = new MyHandler(this);

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
    }

    private void initView() {
        mTextView = findViewById(R.id.textView);
        mButton = findViewById(R.id.button);
        mImageView = findViewById(R.id.imageView);
        mButton.setOnClickListener(this);
        mImageView.setOnTouchListener(this);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.button:
                start();
                break;
        }
    }

    private void start() {
        mTextView.setText("游戏开始了！");
        mButton.setText("游戏中...");
        mButton.setEnabled(false);
        //发送消息
        next(RANDOM_NUMBER);
    }

    private void next(int delayTime) {
        //产生一个0——数组长度的随机数
        int positon = new Random().nextInt(mPosition.length);
        Message message = Message.obtain();
        message.what = CODE;
        message.arg1 = positon;
        mMyHandler.sendMessageDelayed(message, delayTime);
        //每发送一次消息，总数就加一
        mTotalCount++;
    }

    /**
     * 图片点击事件
     * @param v
     * @param event
     * @return
     */
    @Override
    public boolean onTouch(View v, MotionEvent event) {
        //每次触碰到地鼠，则地鼠消失，打到地鼠的数量加一
        v.setVisibility(View.GONE);
        mSuccessCount++;
        mTextView.setText("打到了" + mSuccessCount + "只，共" + MAX_COUNT + "只");
        return false;
    }

    public static class MyHandler extends Handler {
        private final WeakReference<MainActivity> mWeakReference;

        public MyHandler(MainActivity activity) {
            this.mWeakReference = new WeakReference<>(activity);
        }

        @Override
        public void handleMessage(Message msg) {
            MainActivity activity = mWeakReference.get();
            super.handleMessage(msg);
            switch (msg.what) {
                case CODE:
                    if (activity.mTotalCount > MAX_COUNT) {
                        //游戏结束，初始化游戏
                        activity.clear();
                        Toast.makeText(activity, "地鼠打完了！", Toast.LENGTH_SHORT).show();
                        return;
                    } else {
                        int position = msg.arg1;
                        activity.mImageView.setX(activity.mPosition[position][0]);
                        activity.mImageView.setY(activity.mPosition[position][1]);
                        activity.mImageView.setVisibility(View.VISIBLE);
                        //在随机位置上显示地鼠之后，再次发送消息
                        int randomTime = new Random().nextInt(RANDOM_NUMBER) + RANDOM_NUMBER;
                        activity.next(randomTime);
                    }
                    break;
            }
        }
    }

    /**
     * 游戏结束，初始化游戏
     */
    private void clear() {
        mTotalCount = 0;
        mSuccessCount = 0;
        mImageView.setVisibility(View.GONE);
        mButton.setText("点击开始");
        mButton.setEnabled(true);
    }
}