1：WindowManagerService:

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

具体改动的地方看代码吧，

   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;
    }

修改这几处代码便能把系统默认的竖屏变成横屏，但是会有其他的应用出现问题，比如拨号盘原本竖屏显示的，但是在这种横屏模式下打开拨号盘会报空指针错误，进源码一看原来拨号盘也准备了两套的布局，一套横屏一套竖屏的，单独修改windowmanagerservice后不知道为什么这些系统应用没有变成竖屏模式，或许是时间仓促，并没有对windowmanagerservice的流程作很详细的分析，以后有时间再找机会研究下这个流程吧。

2：PhoneWindowManager

1. public int rotationForOrientationLw(int orientation, int lastRotation,  
2.            boolean displayEnabled) {  
3.   
4.        if (mPortraitRotation < 0) {  
5.            // Initialize the rotation angles for each orientation once.  
6.            Display d = ((WindowManager)mContext.getSystemService(Context.WINDOW_SERVICE))  
7.                    .getDefaultDisplay();  
8.            if (d.getWidth() > d.getHeight()) {  
9.                mPortraitRotation = Surface.ROTATION_90;  
10.                mLandscapeRotation = Surface.ROTATION_0;  
11.                mUpsideDownRotation = Surface.ROTATION_270;  
12.                mSeascapeRotation = Surface.ROTATION_180;  
13.            } else {  
14.                mPortraitRotation = Surface.ROTATION_0;  
15.                mLandscapeRotation = Surface.ROTATION_90;  
16.                mUpsideDownRotation = Surface.ROTATION_180;  
17.                mSeascapeRotation = Surface.ROTATION_270;  
18.            }  
19.        }  
20.   
21.     {  
22.         Log.i(TAG, “MediaPlayer.is not PlayingVideo”);  
23.         synchronized (mLock) {  
24.             switch (orientation) {  
25.                 case ActivityInfo.SCREEN_ORIENTATION_PORTRAIT:  
26.                     //always return portrait if orientation set to portrait  
27.                     //return mPortraitRotation;  
28.                     return mUpsideDownRotation;  
29.                 case ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE:  
30.                     //always return landscape if orientation set to landscape  
31.                     return mLandscapeRotation;  
32.                 case ActivityInfo.SCREEN_ORIENTATION_REVERSE_PORTRAIT:  
33.                     //always return portrait if orientation set to portrait  
34.                     //return mUpsideDownRotation;  
35.                     return mPortraitRotation;  
36.                 case ActivityInfo.SCREEN_ORIENTATION_REVERSE_LANDSCAPE:  
37.                     //always return seascape if orientation set to reverse landscape  
38.                     return mSeascapeRotation;  
39.                 case ActivityInfo.SCREEN_ORIENTATION_SENSOR_LANDSCAPE:  
40.                     //return either landscape rotation based on the sensor  
41.                     mOrientationListener.setAllow180Rotation(  
42.                             isLandscapeOrSeascape(Surface.ROTATION_180));  
43.                     return getCurrentLandscapeRotation(lastRotation);  
44.                 case ActivityInfo.SCREEN_ORIENTATION_SENSOR_PORTRAIT:  
45.                     mOrientationListener.setAllow180Rotation(  
46.                             !isLandscapeOrSeascape(Surface.ROTATION_180));  
47.                     return getCurrentPortraitRotation(lastRotation);  
48.             }  
49.   
50.             mOrientationListener.setAllow180Rotation(  
51.                    orientation == ActivityInfo.SCREEN_ORIENTATION_FULL_SENSOR  
52.                    || orientation == ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED);  
53.   
54.             // case for nosensor meaning ignore sensor and consider only lid  
55.             // or orientation sensor disabled  
56.             //or case.unspecified  
57.             if (mLidOpen) {  
58.                 return mLidOpenRotation;  
59.             } else if (mDockMode == Intent.EXTRA_DOCK_STATE_CAR && mCarDockRotation >= 0) {  
60.                 return mCarDockRotation;  
61.             } else if (mDockMode == Intent.EXTRA_DOCK_STATE_DESK && mDeskDockRotation >= 0) {  
62.                 return mDeskDockRotation;  
63.             } else {  
64.                 if (useSensorForOrientationLp(orientation)) {  
65.                     return mOrientationListener.getCurrentRotation(lastRotation);  
66.                 }  
67.                 return Surface.ROTATION_0;  
68.             }  
69.         }  
70. }  
71.    }  

修改上面倒数一行代码把return Surface.ROTATION_0改为你要的方向，记得这个要和上面的匹配，宽高不同，Surface.ROTATION_0也不同。因为代码开头就有

[java] view plaincopy

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. }  

让所有应用都横屏显示:

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;

            }