Android拦截按键

文章目录

• Android拦截按键
• • Android拦截HOME按键
  • Android拦截BACK按键

Android拦截HOME按键

拦截HOME按键需要修改Android的framework层

• 具体代码文件路径android/frameworks/base/services/core/java/com/android/server/policy/PhoneWindowManager.java

PhoneWindowManager的interceptKeyBeforeDispatching方法，这个方法对按键事件做了二次拦截
当返回值为-1则说明事件被拦截，返回值为0则说明事件放开执行。

举例在某个APP中屏蔽对应的HOME按键；

• 如下代码为识别当前的APP是哪个？

public String getTopActivity(Context context){                                                                                                            
         ActivityManager am = (ActivityManager) context.getSystemService(context.ACTIVITY_SERVICE);
          ComponentName cn = am.getRunningTasks(1).get(0).topActivity;
          Log.d(TAG, "pkg:" + cn.getPackageName() + " cls:"+cn.getClassName());//包名加类名
          return cn.getClassName();
     }

public boolean isBackgroundActivity(Context context, String packageName) {
          ActivityManager am = (ActivityManager) context.getSystemService("activity");
         List<ActivityManager.RunningTaskInfo> tasks = am.getRunningTasks(1);
          if (!tasks.isEmpty()) {
              ComponentName topActivity = ((ActivityManager.RunningTaskInfo) tasks.get(0)).topActivity;
              Log.w(TAG, "topActivity packageName = " + topActivity.getPackageName());
              if (!topActivity.getPackageName().equals(packageName)) {
                  Log.w(TAG, packageName + " is background!");
                  return true;
              }
          }
          Log.w(TAG, packageName + " is foreground!");
          return false;
     }

• 如下代码判断针对对应的APP进行HOME按键拦截：

/** {@inheritDoc} */
     @Override
     public long interceptKeyBeforeDispatching(WindowState win, KeyEvent event, int policyFlags) {
......
// First we always handle the home key here, so applications
         // can never break it, although if keyguard is on, we do let
         // it handle it, because that gives us the correct 5 second
         // timeout.
        if (keyCode == KeyEvent.KEYCODE_HOME) {
 
             // If we have released the home key, and didn't do anything else
             // while it was pressed, then it is time to go home!
             if (!down) {
                 //添加的判断当前前台运行APP代码
                 if (!isBackgroundActivity(mContext, PKG_NAME_xxxxx)) {
                         Log.d(TAG, "xxxx app is foreground");
                         if (!getTopActivity(mContext).equals(ACTIVITY_NAME_xxxx)) {                                                          
                                 Log.d(TAG, "xxxxx app is foreground activity");
                                 return -1;
                         }
                        return -1;
                 }
                 
 
                 cancelPreloadRecentApps();

                 mHomePressed = false;
                 if (mHomeConsumed) {
                     mHomeConsumed = false;
                     return -1;
                 }
                 ......

备注：
直接在onKeyDown中判断通过keyCode == KeyEvent.KEYCODE_HOME是不能拦截的

Android拦截BACK按键

这个在Activity中自行重写回调即可，具体见如下示意代码：

@Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if(keyCode == KeyEvent.KEYCODE_BACK){
        	//按键按下时返回处理逻辑可以放在这里
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }

    @Override
    public boolean onKeyUp(int keyCode, KeyEvent event) {
        if(keyCode == KeyEvent.KEYCODE_BACK){
             //按键释放时返回处理逻辑可以放在这里
            return true;
        }
        return super.onKeyUp(keyCode, event);
    }

注：在onKeyDown或onKeyUp中使用return true或return false，都会拦截掉返回按键。