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

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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@Override public 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

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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。