Handler案例-简易打地鼠游戏（延时处理消息）

1. 游戏思路

（1）用ImageView显示地鼠，初始状态将ImageView设置为不可见状态。当开始游戏后，通过sendMessageDelayed()方法延时发送消息，使ImageView显示出来，即实现了地鼠间隔出现的效果。

（2）通过Random获取随机数，给ImageView随机坐标，实现地鼠随机位置出现的效果。

（3）打中1次分数加1，同时记录出现的地鼠数量，当数量达到设定的最大数量，则游戏结束。

2. 代码

布局：

<?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"
    android:background="#FFFFFF"
    tools:context="com.studying.network.GameActivity">

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

    <TextView
        android:id="@+id/text_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="80dp" />

    <Button
        android:id="@+id/button"
        android:layout_width="100dp"
        android:layout_height="40dp"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="20dp"
        android:text="@string/start_game"
        android:textSize="12sp" />

</RelativeLayout>

Activity：

public class GameActivity extends Activity implements View.OnClickListener{

    private ImageView mImageView;
    private TextView mTextView;
    private Button mButton;

    private MyHandler mMyHandler = new MyHandler(this);

    public int mWidth;                              //设备屏幕宽度
    public int mHeight;                             //设备屏幕高度
    private int mTotalCount;                        //已经出现的地鼠数量
    private int mSuccessCount;                      //打中的地鼠数量

    public static final int SHOW_CODE = 100001;     //消息标识
    public static final int MAX_COUNT = 10;         //会出现的全部地鼠数量
    public static final int RANDOM_TIME = 500;      //地鼠出现的随机时间最大值

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

        initView();
        setTitle("打地鼠");
        DisplayMetrics dm = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(dm);
        mWidth = dm.widthPixels;
        mHeight = dm.heightPixels;
    }

    private void initView() {
        mImageView = (ImageView) findViewById(R.id.image_view);
        mTextView = (TextView) findViewById(R.id.text_view);
        mButton = (Button) findViewById(R.id.button);
        mImageView.setOnClickListener(this);
        mButton.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.button:
                start();
                break;
            case R.id.image_view:
                mImageView.setVisibility(View.GONE);
                mSuccessCount++;
                mTextView.setText("打到了" + mSuccessCount + "只，共" + MAX_COUNT + "只");
                break;
        }
    }

    //游戏初始化
    private void start() {
        mTextView.setText("开始游戏！");
        mButton.setText("游戏中");
        mButton.setEnabled(false);
        next(0);
    }

    //设置下一只地鼠的出现
    private void next(int delayTime) {
        int positionX = new Random().nextInt(mWidth - 160);
        int positionY = new Random().nextInt(mHeight - 320);

        Message message = Message.obtain();
        message.what = SHOW_CODE;
        message.arg1 = positionX;
        message.arg2 = positionY;

        mMyHandler.sendMessageDelayed(message, delayTime);
        mTotalCount++;
    }

    private static class MyHandler extends Handler {

        private WeakReference<GameActivity>weakReference;

        MyHandler(GameActivity activity) {
            this.weakReference = new WeakReference<>(activity);
        }

        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            GameActivity activity = weakReference.get();

            switch (msg.what) {
                case SHOW_CODE:
                    //游戏结束条件
                    if (activity.mTotalCount > MAX_COUNT) {
                        activity.clear();
                        Toast.makeText(activity, "地鼠打完了！", Toast.LENGTH_SHORT).show();
                        return;
                    }

                    //设置地鼠定时出现
                    int positionX = msg.arg1;
                    int positionY = msg.arg2;
                    activity.mImageView.setX(positionX);
                    activity.mImageView.setY(positionY);
                    activity.mImageView.setVisibility(View.VISIBLE);
                    int randomTime = new Random().nextInt(RANDOM_TIME) + RANDOM_TIME;
                    activity.next(randomTime);
                    break;
            }
        }
    }

    //重置游戏数据
    private void clear() {
        mTotalCount = 0;
        mSuccessCount = 0;
        mImageView.setVisibility(View.GONE);
        mButton.setText("开始游戏");
        mButton.setEnabled(true);
    }
}