把Bitmap对象转为文件

/**  
* 将Bitmap转换成文件
 * 保存文件  
 * @param bm  
 * @param fileName  
 * @throws IOException  
 */    
public static File saveFile(Bitmap bm,String path, String fileName) throws IOException {   
    File dirFile = new File(path);    
    if(!dirFile.exists()){    
        dirFile.mkdir();    
    }    
    File myCaptureFile = new File(path , fileName);    
    BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(myCaptureFile));    
    bm.compress(Bitmap.CompressFormat.JPEG, 80, bos);    
    bos.flush();    
    bos.close();    
    return myCaptureFile;
}