Android系统onKeyDown监控/拦截/监听/屏蔽返回键、菜单键和Home键

来源：互联网发布：ios景深软件编辑：程序博客网时间：2024/05/21 18:06

在Android系统中用来显示界面的组件（Component）为Activity，也就是说只有重写Activity的onKeyDown方法来监控/拦截/屏蔽系统的返回键（back）、菜单键（Menu）及Home键

1、拦截/屏蔽返回键、菜单键实现代码

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@Overridepublic boolean onKeyDown(int keyCode, KeyEvent event) {    if(keyCode == KeyEvent.KEYCODE_BACK) { //监控/拦截/屏蔽返回键        processExit();        return true;    } else if(keyCode == KeyEvent.KEYCODE_MENU) {        //监控/拦截菜单键    } else if(keyCode == KeyEvent.KEYCODE_HOME) {        //由于Home键为系统键，此处不能捕获，需要重写onAttachedToWindow()    }    return super.onKeyDown(keyCode, event);}

2、拦截/屏蔽系统Home键

public void onAttachedToWindow() {       this.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD);          super.onAttachedToWindow();    }

为什么必须重写onAttachedToWindow()，看看下面的代码就知道了
/frameworks/policies/base/phone/com/android/internal/policy/impl/PhoneWindowManager.java 1000行附近

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if (code == KeyEvent.KEYCODE_HOME) {      // If a system window has focus, then it doesn't make sense      // right now to interact with applications.      WindowManager.LayoutParams attrs = win != null ? win.getAttrs() : null;      if (attrs != null) {          final int type = attrs.type;          if (type == WindowManager.LayoutParams.TYPE_KEYGUARD                  || type == WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG) {                  // the "app" is keyguard, so give it the key                  return false;          }          final int typeCount = WINDOW_TYPES_WHERE_HOME_DOESNT_WORK.length;          for (int i=0; i<typeCount; i++) {              if (type == WINDOW_TYPES_WHERE_HOME_DOESNT_WORK[i]) {                  // don't do anything, but also don't pass it to the app                  return true;              }          }      } }

当然，重写View的onKeyDown也可以实现，但View如果没有获得焦点，那就不能监控/拦截返回键、菜单键和Home键,所有还是重写Activity的onKeyDown方法比较好。