<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"></uses-permission>

"android.permission.MOUNT_UNMOUNT_FILESYSTEMS"-->允许挂载和反挂载文件系统可移动存储
"android.permission.WRITE_EXTERNAL_STORAGE"-->模拟器中sdcard中创建文件夹的权限

private void saveBitmap(Bitmap bitmap,String bitName) throws IOException
  {
    File file = new File("/sdcard/DCIM/Camera/"+bitName);
    if(file.exists()){
      file.delete();
    }
    FileOutputStream out;
    try{
      out = new FileOutputStream(file);
      if(bitmap.compress(Bitmap.CompressFormat.PNG, 90, out))
      {
        out.flush();
        out.close();
      }
    }
    catch (FileNotFoundException e)
    {
      e.printStackTrace();
    }
    catch (IOException e)
    {
      e.printStackTrace();
    }
  }

public void saveMyBitmap(String bitName) throws IOException { 
  File f = new File("/sdcard/Note/" + bitName + ".png"); 
  f.createNewFile(); 
  FileOutputStream fOut = null; 
  try { 
      fOut = new FileOutputStream(f); 
  } catch (FileNotFoundException e) { 
      e.printStackTrace(); 
  } 
  mBitmap.compress(Bitmap.CompressFormat.PNG, 100, fOut); 
  try { 
      fOut.flush(); 
  } catch (IOException e) { 
      e.printStackTrace(); 
  } 
  try { 
      fOut.close(); 
  } catch (IOException e) { 
      e.printStackTrace(); 
  } 
}