有关Bitmap的转图片，压缩，以及Base64加密。

1.转图片：

public void saveBitmap(Bitmap bitmap) {
 首先保存图片 File appDir = new File(Environment.getExternalStorageDirectory(),"zxing_image"); 
 if (!appDir.exists()) 
 { appDir.mkdir(); } 
 String fileName = "zxing_image" + ".png"; 
 file = new File(appDir, fileName);
 try { FileOutputStream fos = new FileOutputStream(file);
 bitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos);
 fos.flush(); fos.close(); }
 catch (Exception e) { e.printStackTrace(); }｝
}

2.Bitmap压缩：

public static Bitmap compressImage(Bitmap image) {
 ByteArrayOutputStream baos = new ByteArrayOutputStream();
 image.compress(Bitmap.CompressFormat.JPEG, 50, baos);//质量压缩方法，这里100表示不压缩，把压缩后的数据存放到baos中  
 int options = 90;
 while (baos.toByteArray().length / 1024 > 50) {//循环判断若是压缩后图片是否大于100kb,大于继续压缩
 baos.reset();//重置baos即清空baos 
 image.compress(Bitmap.CompressFormat.JPEG, options, baos);//这里压缩options%，把压缩后的数据存放到baos中 
 options -= 10;//每次都减小10
 }
 ByteArrayInputStream isBm = new ByteArrayInputStream(baos.toByteArray());//把压缩后的数据baos存放到ByteArrayInputStream中 
 Bitmap bitmap = BitmapFactory.decodeStream(isBm, null, null);//把ByteArrayInputStream数据生成图片
 return bitmap;
}

3.Bitmap转Base64：

public static String bitmapToBase64(Bitmap bitmap) {

 String result = null;
 ByteArrayOutputStream baos = null;
 try {
 if (bitmap != null) {
 baos = new ByteArrayOutputStream();
 bitmap.compress(Bitmap.CompressFormat.JPEG, 100, baos);

 baos.flush();
 baos.close();

 byte[] bitmapBytes = baos.toByteArray();
 result = Base64.encodeToString(bitmapBytes, Base64.DEFAULT);
 }
 } catch (IOException e) {
 e.printStackTrace();
 } finally {
 try {
 if (baos != null) {
 baos.flush();
 baos.close();
 }
 } catch (IOException e) {
 e.printStackTrace();
 }
 }
 return result;}