强制系统横屏竖屏

方法一：

/frameworks/base/services/java/com/android/server/wm/WindowManagerService.java

int computeForcedAppOrientationLocked() {  
       int req = getOrientationFromWindowsLocked();  
       if (req == ActivityInfo.SCREEN_ORIENTATION_UNSPECIFIED) {  
           req = getOrientationFromAppTokensLocked();  
       }  
       // req = ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE; //强制横屏0度  
       // req = ActivityInfo.SCREEN_ORIENTATION_PORTRAIT; //强制竖屏左转90度  
       return req;  
}  

方法二：

/frameworks/base/services/surfaceflinger/SurfaceFlinger.cpp

void GraphicPlane::setDisplayHardware(DisplayHardware *hw)  
{  
mHw = hw;  
// initialize the display orientation transform.  
// it's a constant that should come from the display driver.  
int displayOrientation = ISurfaceComposer::eOrientationDefault;  
char property[PROPERTY_VALUE_MAX];  
if (property_get("ro.sf.hwrotation", property, NULL) > 0) {  
//displayOrientation  
switch (atoi(property)) {  
case 0:  
displayOrientation = ISurfaceComposer::eOrientationDefault;  
break;  
case 90:  
displayOrientation = ISurfaceComposer::eOrientation90;  
break;  
case 180:  
displayOrientation = ISurfaceComposer::eOrientation180;  
break;  
case 270:  
displayOrientation = ISurfaceComposer::eOrientation270;  
break;  
}  
}  
/* 强制旋转90度 */  
displayOrientation = ISurfaceComposer::eOrientation90;  
const float w = hw->getWidth();  
const float h = hw->getHeight();  
GraphicPlane::orientationToTransfrom(displayOrientation, w, h,  
&mDisplayTransform);  
}