Android下Dialog及Activity屏蔽Home鍵詳解

屏蔽其他鍵，重寫onKeyDown
Java代碼

1. @Override
2. public boolean onKeyDown(int keyCode, KeyEvent event) {
3. Log.i(TAG,"keycode="+keyCode + " isBan="+isBan);
4. switch (keyCode) {
5. case KeyEvent.KEYCODE_BACK:
6. Log.i(TAG,"KEYCODE_BACK");
7. return true;
8. }
9. return super.onKeyDown(keyCode, event);
10. }

大家會發現，這裡屏蔽Home鍵是捕捉不到的，因為大家的權限一般是User所以是無效的。
而其實Android處理Home鍵等系統級按鍵是有一定的處理的。
看看源碼是怎樣處理的 \frameworks\policies\base\phone\com\android\internal\policy\impl\PhoneWindowManager.java #1092 Java代碼

1. // First we always handle the home key here, so applications
2. // can never break it, although if keyguard is on, we do let
3. // it handle it, because that gives us the correct 5 second
4. // timeout.
5. if (code == KeyEvent.KEYCODE_HOME) {
7. // If a system window has focus, then it doesn't make sense
8. // right now to interact with applications.
9. WindowManager.LayoutParams attrs = win != null ? win.getAttrs() : null;
10. if (attrs != null) {
11. final int type = attrs.type;
12. if (type == WindowManager.LayoutParams.TYPE_KEYGUARD
13. || type == WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG) {
14. // the "app" is keyguard, so give it the key
15. return false;
16. }
17. final int typeCount = WINDOW_TYPES_WHERE_HOME_DOESNT_WORK.length;
18. for (int i=0; i<typeCount; i++) {
19. if (type == WINDOW_TYPES_WHERE_HOME_DOESNT_WORK[i]) {
20. // don't do anything, but also don't pass it to the app
21. return true;
22. }
23. }
24. }

通過源碼，我們不難發現兩個的參數 WindowManager.LayoutParams.TYPE_KEYGUARD和
WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG
借鑒於此，重寫onAttachedToWindow，以實現屏蔽Home鍵 Java代碼

1. public void onAttachedToWindow() {
2. this.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD);
3. super.onAttachedToWindow();
4. }

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 華麗的分界線- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

輪到dialog了，如果在Activity彈出dialog，在Activity設置以上2個方法是沒辦法屏蔽的。
其實，原理是一樣的，只是地方不一樣而已。
Java代碼

1. final Dialog dialog = new Dialog(this);
2. dialog.setContentView(R.layout.mydailog);
3. dialog.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD);
4. dialog.show();
6. dialog.setOnKeyListener(new android.content.DialogInterface.OnKeyListener(){
7. @Override
8. public boolean onKey(DialogInterface dialog, int keyCode,KeyEvent event) {
9. switch (keyCode) {
10. case KeyEvent.KEYCODE_BACK:
11. Log.i(TAG,"KEYCODE_BACK");
12. return true;
13. }
14. return false;
15. }
16. });

這樣運行後，出錯如下：
Error代碼

1. 10-18 13:27:06.380: ERROR/AndroidRuntime(4684): Caused by: android.view.WindowManager$BadTokenException: Unable to add window android.view.ViewRoot$W@2b046d68 -- permission denied for this window type

其實，只需要把dialog.getWindow().setType的位置放在show後面就可以了
正確代碼

1. dialog.show();
2. dialog.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD);

這麼，就完成了Back鍵的屏蔽 和Home鍵盤的屏蔽了！

總結：
1:)在以上用WindowManager.LayoutParams.TYPE_KEYGUARD的地方改用
WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG 效果一樣。至於兩者的具體差別，得以後再研究研究。

2:)其實，在源碼裡是這樣調用的。 Java代碼

1. final AlertDialog dialog = new AlertDialog.Builder(mContext)
2. .setTitle(null)
3. .setMessage(message)
4. .setNeutralButton(R.string.ok, null)
5. .create();
6. dialog.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG);
7. dialog.show();

但我們如果這樣調用就會出現之前的那個error：permission denied for this window type 這就顯而易見了吧~~

3:)ProgressDialog 默認屏蔽 Back鍵，Dialog，AlertDialog則需setOnKeyListener

4:)其實屏蔽Home鍵，在頁面的某個地方，例如一個Button的onClick裡，去設置setType就可以了,如：
Java代碼

1. button.setOnClickListener(new View.OnClickListener() {
2. @Override
3. public void onClick(View v) {
4. getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD);
5. }
6. });

但前提是重載Activity的onAttachedToWindow()，哪怕只是一個空實現，然後返回父類方法。
Java代碼

1. @Override
2. public void onAttachedToWindow() {
3. super.onAttachedToWindow();
4. }

5:)其實它們，都是常用的~ Java代碼

1. switch (keyCode) {
2. case KeyEvent.KEYCODE_HOME:
3. Log.i(TAG,"KEYCODE_HOME");
4. return true;
5. case KeyEvent.KEYCODE_BACK:
6. Log.i(TAG,"KEYCODE_BACK");
7. return true;
8. case KeyEvent.KEYCODE_CALL:
9. Log.i(TAG,"KEYCODE_CALL");
10. return true;
11. case KeyEvent.KEYCODE_SYM:
12. Log.i(TAG,"KEYCODE_SYM");
13. return true;
14. case KeyEvent.KEYCODE_VOLUME_DOWN:
15. Log.i(TAG,"KEYCODE_VOLUME_DOWN");
16. return true;
17. case KeyEvent.KEYCODE_VOLUME_UP:
18. Log.i(TAG,"KEYCODE_VOLUME_UP");
19. return true;
20. case KeyEvent.KEYCODE_STAR:
21. Log.i(TAG,"KEYCODE_STAR");
22. return true;
23. }