public void encodeImage(Bitmap bitmap){
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    //读取图片到ByteArrayOutputStream
    bitmap.compress(Bitmap.CompressFormat.PNG, 40, baos); //参数如果为100那么就不压缩
    byte[] bytes = baos.toByteArray();
    String strbm = Base64.encodeToString(bytes,Base64.DEFAULT);
  }

public void sendImage(String bmMsg){
byte [] input = Base64.decode(bmMsg, Base64.DEFAULT);
Bitmap bitmap = BitmapFactory.decodeByteArray(input, 0, input.length);
 }

public Bitmap stringToBitmap(String string) {
    Bitmap bitmap = null;
    try {
      byte[] bitmapArray = Base64.decode(string.split(",")[1], Base64.DEFAULT);
      bitmap = BitmapFactory.decodeByteArray(bitmapArray, 0, bitmapArray.length);
    } catch (Exception e) {
      e.printStackTrace();
    }
    return bitmap;
  }