在想要横屏的Activity中修改其onResume方法

    @Override  
        protected void onResume() {  
            // TODO Auto-generated method stub  
            /** 
             * 设置为横屏 
             */  
            if (getRequestedOrientation() != ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE) {  
                setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);  
            }  
      
            super.onResume();  
        }