事件的监听和处理

package com.crazyit.ui.viewlistener;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.view.View;

/**
 * 作者：Gaao on 2016/6/5 19:52
 */
public class PlaneView extends View {

    public float currentX;
    public  float currentY;
    Bitmap bitmap;


    public PlaneView(Context context) {
        super(context);
        //定义飞机的图片
        bitmap = BitmapFactory.decodeResource(context.getResources(),R.drawable.plane);
        setFocusable(true);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        //创建画笔
        Paint paint = new Paint();
        //绘制飞机
        canvas.drawBitmap(bitmap,currentX,currentY,paint);
    }
}

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该实例直接使用 planeView 作为 Activity 显示的内容,并为planeView增加键盘事件监听监听器.

处理View的 Activity

package com.crazyit.ui.viewlistener;

import android.app.Activity;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.view.Display;
import android.view.KeyEvent;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;

/**
 * 飞机游戏的 例子
 */
public class PlaneGameActivity extends Activity {

    //定义飞机移动的速度
    private int speed = 10;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //去掉窗口的标题
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        //全屏显示
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
        //创建planeView组件
        final PlaneView planeView = new PlaneView(this);

        setContentView(planeView);

        planeView.setBackgroundResource(R.drawable.back); //设背景

        //获取窗口管理器
        WindowManager windowManager = getWindowManager();
        Display display = windowManager.getDefaultDisplay();
      final   DisplayMetrics metrics = new DisplayMetrics();

        //获得屏幕的宽和高
        display.getMetrics(metrics);

        //设置飞机的初始位置
        planeView.currentX = metrics.widthPixels / 2;
        planeView.currentY = metrics.heightPixels - 40;

        //为 planeView 组件添加 键盘监听事件
        planeView.setOnKeyListener(new View.OnKeyListener() {
            @Override
            public boolean onKey(View v, int keyCode, KeyEvent event) {
                //获取是由哪一个键 触发的事件
                switch (event.getKeyCode()) {
                    //控制飞机下移
                    case KeyEvent.KEYCODE_S:
                        planeView.currentY += speed;
                        if (planeView.currentY>metrics.heightPixels){
                            planeView.currentY=metrics.heightPixels-50;
                        }
                        break;
                    //控制飞机上移
                    case KeyEvent.KEYCODE_W:
                        planeView.currentY -= speed;
                        if (planeView.currentY<0){
                            planeView.currentY=0;
                        }
                        break;
                    //控制飞机左移
                    case KeyEvent.KEYCODE_A:
                        planeView.currentX -= speed;

                        if (planeView.currentX<0){
                            planeView.currentX=0;
                        }
                        break;
                    //控制飞机右移
                    case KeyEvent.KEYCODE_D:

                        planeView.currentX += speed;

                        if (planeView.currentX>metrics.widthPixels){
                            planeView.currentX=metrics.widthPixels;
                        }
                        break;

                }

                //通知 planeView 组件重绘
                planeView.invalidate();
                return true;
            }
        });

    }
}