android 鍵盤事件和屏幕事件的運行原理及交互實現

2020-04-11 12:35:55

字體：大中小

來源：轉載

供稿：網友

當在自定義View或者做游戲的時候，我們常常會用到鍵盤觸發事件和屏幕觸發事件！在自定義的View里的鍵盤觸發事件（比如：onKeyDown(int keyCode, KeyEvent event)）和屏幕觸發事件（onTouchEvent(MotionEvent event)）和activity里的鍵盤觸發事件（比如：onKeyDown(int keyCode, KeyEvent event)）和屏幕觸發事件（onTouchEvent(MotionEvent event)）是怎么樣交互的呢？是怎樣的一個運行原理呢？下面來看看：

1、屏幕觸發事件：哪個activity或者視圖，控件在最上層就最先觸發這個控件里的屏幕觸發事件，返回值如果是默認或者false就會一層一層的往下傳遞！如果返回值是true,則在執行完動作之后不會往下傳遞！
2、鍵盤觸發事件：這個原理和屏幕觸發事件差不多，但是不同的時，在沒有設置控件處于焦點時，一般按鍵盤里的按鍵觸發的是activity里的鍵盤觸發事件（比如：onKeyDown(int keyCode, KeyEvent event)）。

下面來舉個例子：
比如在做游戲的時候，我們經常自定義視圖，我們一般都喜歡和使用觸發本視圖（GameView）里的鍵盤觸發事件和屏幕觸發事件，但是比如：onKeyDown(int keyCode, KeyEvent event）)，一般我們按鍵盤的時候直接觸發的是activity里的鍵盤觸發事件，怎樣讓它直接觸發（GameView）里的鍵盤觸發事件呢?

第一種方法：
例子1：

復制代碼代碼如下:

 
View Code 
package net.loonggg.project; 
import android.app.Activity; 
import android.os.Bundle; 
import android.view.KeyEvent; 
import android.view.MotionEvent; 
public class MainActivity extends Activity { 
private GameView gameView; 
@Override 
public void onCreate(Bundle savedInstanceState) { 
super.onCreate(savedInstanceState); 
gameView = new GameView(this); 
setContentView(gameView); 
} 
@Override 
public boolean onKeyDown(int keyCode, KeyEvent event) { 
System.out.println("MainActivity:" + " keyCode:" + keyCode + " evnet:" 
+ event); 
return super.onKeyDown(keyCode, event); 
} 
@Override 
public boolean onTouchEvent(MotionEvent event) { 
System.out.println("MainActivity:" + " event:" + event + " x:" 
+ event.getX() + " y:" + event.getY()); 
return super.onTouchEvent(event); 
} 
} 
package net.loonggg.project; 
import android.content.Context; 
import android.graphics.Canvas; 
import android.graphics.Color; 
import android.graphics.Paint; 
import android.view.KeyEvent; 
import android.view.MotionEvent; 
import android.view.View; 
public class GameView extends View { 
private Paint paint; 
private int pointX; 
private int pointY; 
public GameView(Context context) { 
super(context); 
// 設置GameView獲得焦點 
this.setFocusable(true); 
paint = new Paint(); 
paint.setColor(Color.YELLOW); 
Thread t = new Thread(new MyThread()); 
t.start(); 
} 
@Override 
protected void onDraw(Canvas canvas) { 
super.onDraw(canvas); 
canvas.drawCircle(pointX, pointY, 15, paint); 
} 
class MyThread implements Runnable { 
@Override 
public void run() { 
while (true) { 
try { 
Thread.sleep(3000); 
pointY = pointY + 10; 
pointX = pointX + 10; 
if (pointX > 200) { 
break; 
} 
} catch (InterruptedException e) { 
e.printStackTrace(); 
} 
GameView.this.postInvalidate(); 
} 
} 
} 
@Override 
public boolean onKeyDown(int keyCode, KeyEvent event) { 
System.out.println("GameView:" + " keyCode:" + keyCode + " evnet:" 
+ event); 
//此事件不會傳播出去 
return true; 
} 
@Override 
public boolean onTouchEvent(MotionEvent event) { 
System.out.println("GameView:" + " event:" + event + " x:" 
+ event.getX() + " y:" + event.getY()); 
//此事件不會傳播出去 
return true; 
} 
} 

第二種方法：

復制代碼代碼如下:

 
View Code 
package net.loonggg.project; 
import android.app.Activity; 
import android.os.Bundle; 
import android.view.KeyEvent; 
import android.view.MotionEvent; 
public class MainActivity extends Activity { 
private GameView gameView; 
@Override 
public void onCreate(Bundle savedInstanceState) { 
super.onCreate(savedInstanceState); 
gameView = new GameView(this); 
setContentView(gameView); 
} 
@Override 
public boolean onKeyDown(int keyCode, KeyEvent event) { 
System.out.println("MainActivity:" + " keyCode:" + keyCode + " evnet:" 
+ event); 
//把事件傳遞給gameView 
gameView.onKeyDown(keyCode, event); 
return super.onKeyDown(keyCode, event); 
} 
@Override 
public boolean onTouchEvent(MotionEvent event) { 
System.out.println("MainActivity:" + " event:" + event + " x:" 
+ event.getX() + " y:" + event.getY()); 
//把事件傳遞給gameView 
gameView.onTouchEvent(event); 
return super.onTouchEvent(event); 
} 
} 
package net.loonggg.project; 
import android.content.Context; 
import android.graphics.Canvas; 
import android.graphics.Color; 
import android.graphics.Paint; 
import android.view.KeyEvent; 
import android.view.MotionEvent; 
import android.view.View; 
public class GameView extends View { 
private Paint paint; 
private int pointX; 
private int pointY; 
public GameView(Context context) { 
super(context); 
paint = new Paint(); 
paint.setColor(Color.YELLOW); 
Thread t = new Thread(new MyThread()); 
t.start(); 
} 
@Override 
protected void onDraw(Canvas canvas) { 
super.onDraw(canvas); 
canvas.drawCircle(pointX, pointY, 15, paint); 
} 
class MyThread implements Runnable { 
@Override 
public void run() { 
while (true) { 
try { 
Thread.sleep(3000); 
pointY = pointY + 10; 
pointX = pointX + 10; 
if (pointX > 200) { 
break; 
} 
} catch (InterruptedException e) { 
e.printStackTrace(); 
} 
GameView.this.postInvalidate(); 
} 
} 
} 
@Override 
public boolean onKeyDown(int keyCode, KeyEvent event) { 
System.out.println("GameView:" + " keyCode:" + keyCode + " evnet:" 
+ event); 
return super.onKeyDown(keyCode, event); 
} 
@Override 
public boolean onTouchEvent(MotionEvent event) { 
System.out.println("GameView:" + " event:" + event + " x:" 
+ event.getX() + " y:" + event.getY()); 
return super.onTouchEvent(event); 
} 
} 

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android 鍵盤事件和屏幕事件的運行原理及交互實現