1：WindowManagerService:

platform\frameworks\base\services\core\java\com\android\server\wm\WindowManagerService.class 

具體改動的地方看程式碼吧，

   public int getOrientationFromWindowsLocked() {
        ....
        -- return (mLastWindowForcedOrientation=ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED);
        ++ return (mLastWindowForcedOrientation=ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
    }
 

  /*
     * Determine the new desired orientation of the display, returning
     * a non-null new Configuration if it has changed from the current
     * orientation.  IF TRUE IS RETURNED SOMEONE MUST CALL
     * setNewConfiguration() TO TELL THE WINDOW MANAGER IT CAN UNFREEZE THE
     * SCREEN.  This will typically be done for you if you call
     * sendNewConfiguration().
     *
     * The orientation is computed from non-application windows first. If none of
     * the non-application windows specify orientation, the orientation is computed from
     * application tokens.
     * @see android.view.IWindowManager#updateOrientationFromAppTokens(
     * android.os.IBinder)
     */
    boolean updateOrientationFromAppTokensLocked(boolean inTransaction) {
        long ident = Binder.clearCallingIdentity();
        try {
            int req = getOrientationFromWindowsLocked();
            if (req == ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED) {
-- mForcedAppOrientation = req;
-- req = getOrientationFromAppTokensLocked();
         ++req=ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE;
            }

            if (req != mForcedAppOrientation) {
                -- mForcedAppOrientation = req;
                ++ mForcedAppOrientation = ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE;
....
    }
 

    boolean computeScreenConfigurationLocked(Configuration config) {

....
        if (config != null) {
            -- config.orientation = (dw <= dh) ? Configuration.ORIENTATION_PORTRAIT:Configuration.ORIENTATION_LANDSCAPE;
            ++ config.orientation = Configuration.ORIENTATION_LANDSCAPE;
        }

....
        return true;
    }
 

修改這幾處程式碼便能把系統預設的豎屏變成橫屏，但是會有其他的應用出現問題，比如撥號盤原本豎屏顯示的，但是在這種橫屏模式下開啟撥號盤會報空指標錯誤，進原始碼一看原來撥號盤也準備了兩套的佈局，一套橫屏一套豎屏的，單獨修改windowmanagerservice後不知道為什麼這些系統應用沒有變成豎屏模式，或許是時間倉促，並沒有對windowmanagerservice的流程作很詳細的分析，以後有時間再找機會研究下這個流程吧。

2：PhoneWindowManager

1. public int rotationForOrientationLw(int orientation, int lastRotation,  
2.            boolean displayEnabled) {  
3.        if (mPortraitRotation < 0) {  
4.            // Initialize the rotation angles for each orientation once.  
5.            Display d = ((WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE))  
6.                    .getDefaultDisplay();  
7.            if (d.getWidth() > d.getHeight()) {  
8.                mPortraitRotation = Surface.ROTATION_90;  
9.                mLandscapeRotation = Surface.ROTATION_0;  
10.                mUpsideDownRotation = Surface.ROTATION_270;  
11.                mSeascapeRotation = Surface.ROTATION_180;  
12.            } else {  
13.                mPortraitRotation = Surface.ROTATION_0;  
14.                mLandscapeRotation = Surface.ROTATION_90;  
15.                mUpsideDownRotation = Surface.ROTATION_180;  
16.                mSeascapeRotation = Surface.ROTATION_270;  
17.            }  
18.        }  
19.     {  
20.         Log.i(TAG, "MediaPlayer.is not PlayingVideo");  
21.         synchronized (mLock) {  
22.             switch (orientation) {  
23.                 case ActivityInfo.SCREEN_ORIENTATION_PORTRAIT:  
24.                     //always return portrait if orientation set to portrait  
25.                     //return mPortraitRotation;  
26.                     return mUpsideDownRotation;  
27.                 case ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE:  
28.                     //always return landscape if orientation set to landscape  
29.                     return mLandscapeRotation;  
30.                 case ActivityInfo.SCREEN_ORIENTATION_REVERSE_PORTRAIT:  
31.                     //always return portrait if orientation set to portrait  
32.                     //return mUpsideDownRotation;  
33.                     return mPortraitRotation;  
34.                 case ActivityInfo.SCREEN_ORIENTATION_REVERSE_LANDSCAPE:  
35.                     //always return seascape if orientation set to reverse landscape  
36.                     return mSeascapeRotation;  
37.                 case ActivityInfo.SCREEN_ORIENTATION_SENSOR_LANDSCAPE:  
38.                     //return either landscape rotation based on the sensor  
39.                     mOrientationListener.setAllow180Rotation(  
40.                             isLandscapeOrSeascape(Surface.ROTATION_180));  
41.                     return getCurrentLandscapeRotation(lastRotation);  
42.                 case ActivityInfo.SCREEN_ORIENTATION_SENSOR_PORTRAIT:  
43.                     mOrientationListener.setAllow180Rotation(  
44.                             !isLandscapeOrSeascape(Surface.ROTATION_180));  
45.                     return getCurrentPortraitRotation(lastRotation);  
46.             }  
47.             mOrientationListener.setAllow180Rotation(  
48.                    orientation == ActivityInfo.SCREEN_ORIENTATION_FULL_SENSOR  
49.                    || orientation == ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED);  
50.             // case for nosensor meaning ignore sensor and consider only lid  
51.             // or orientation sensor disabled  
52.             //or case.unspecified  
53.             if (mLidOpen) {  
54.                 return mLidOpenRotation;  
55.             } else if (mDockMode == Intent.EXTRA_DOCK_STATE_CAR && mCarDockRotation >= 0) {  
56.                 return mCarDockRotation;  
57.             } else if (mDockMode == Intent.EXTRA_DOCK_STATE_DESK && mDeskDockRotation >= 0) {  
58.                 return mDeskDockRotation;  
59.             } else {  
60.                 if (useSensorForOrientationLp(orientation)) {  
61.                     return mOrientationListener.getCurrentRotation(lastRotation);  
62.                 }  
63.                 return Surface.ROTATION_0;  
64.             }  
65.         }  
66. }  
67.    }  

修改上面倒數一行程式碼把return Surface.ROTATION_0改為你要的方向，記得這個要和上面的匹配，寬高不同，Surface.ROTATION_0也不同。因為程式碼開頭就有

1. if (mPortraitRotation < 0) {  
2.     // Initialize the rotation angles for each orientation once.  
3.     Display d = ((WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE))  
4.             .getDefaultDisplay();  
5.     if (d.getWidth() > d.getHeight()) {  
6.         mPortraitRotation = Surface.ROTATION_90;  
7.         mLandscapeRotation = Surface.ROTATION_0;  
8.         mUpsideDownRotation = Surface.ROTATION_270;  
9.         mSeascapeRotation = Surface.ROTATION_180;  
10.     } else {  
11.         mPortraitRotation = Surface.ROTATION_0;  
12.         mLandscapeRotation = Surface.ROTATION_90;  
13.         mUpsideDownRotation = Surface.ROTATION_180;  
14.         mSeascapeRotation = Surface.ROTATION_270;  
15.     }  
16. }  

讓所有應用都橫屏顯示:

frameworks/base/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java

    public int rotationForOrientationLw(int orientation, int lastRotation,

            boolean displayEnabled) {

            // Initialize the rotation angles for each orientation once.

            Display d = ((WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE))

                    .getDefaultDisplay();

            if (d.getWidth() > d.getHeight()) {

                mPortraitRotation = Surface.ROTATION_0;  //jeff. ROTATION_90;

                mLandscapeRotation = Surface.ROTATION_0;

                mUpsideDownRotation = Surface.ROTATION_90;  //jeff. 270;

                mSeascapeRotation = Surface.ROTATION_180;

            }