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

【Android系统onKeyDown监控/拦截/监听/屏蔽返回键、菜单键和Home键】 参考：http://orgcent.com/android-back-menu-home-onkeydown/

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

12

 @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

4

 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

21

 /frameworks 
/policies 
/base 
/phone 
/com 
/android 
/internal 
/policy 
/impl 
/PhoneWindowManager. 
java
1000行附近 

 
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 

if
(type
== WINDOW_TYPES_WHERE_HOME_DOESNT_WORK 
[i 
] 
)
{


// don't do anything, but also don't pass it to the app


return
true 
;



}


}


}

 
} 