有關bitmap的操作一直很多，這裡特此總結一下：

public class BitmapTransformUtils {

    //根據圖片uri生成Bitmap物件
public static Bitmap getBitmapByUrl(Context context, Uri uri) {
        if (uri == null)
            return null;
Bitmap bitmap = null;
        try {
            bitmap = BitmapFactory.decodeStream(context.getContentResolver().openInputStream(uri));
 
} catch (FileNotFoundException e) {
            e.printStackTrace();
            return null;
}
        return bitmap;
}

    //bitmap 轉base64
public static String getBase64ByBitmap(Bitmap bitmap) {
        ByteArrayOutputStream out = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.JPEG
 
, 100, out);
        try {
            out.flush();
out.close();
} catch (IOException e) {
            e.printStackTrace();
}
        return Base64.encodeToString(out.toByteArray(), Base64.DEFAULT);
}

    //base64轉成bitmap
public static Bitmap getBitmapByBase64(String string) {
        Bitmap bitmap = null;
 
        try {
            byte[] bitmapArray;
bitmapArray = Base64.decode(string, Base64.DEFAULT);
bitmap = BitmapFactory.decodeByteArray(bitmapArray, 0, bitmapArray.length);
            return bitmap;
} catch (Exception e) {
            e.printStackTrace();
}
        return null;
}

    //根據本地圖片路徑String轉base64
public static String getFileBase64String(String path) {
        File file = new File(path);
        try {
            FileInputStream in = new FileInputStream(file);
ByteArrayOutputStream out = new ByteArrayOutputStream();
            int i = in.read();
            while (i != -1) {
                out.write(i);
i = in.read();
}
            return Base64.encodeToString(out.toByteArray(), Base64.DEFAULT);
} catch (Exception e) {
            e.printStackTrace();
}
        return null;
}

    //載入本地圖片
public static Bitmap getLoacalBitmap(String url) {
        try {
            FileInputStream fis = new FileInputStream(url);
            return BitmapFactory.decodeStream(fis);
} catch (FileNotFoundException e) {
            e.printStackTrace();
            return null;
}
    }

    //將Bitmap儲存在本地
public static void saveBitmap(Context context, Bitmap bitmap) {
        //首先儲存bitmap
File file=new File(Environment.getExternalStorageDirectory(),"bitmap" );
        if (!file.exists()){
            file.mkdir();
}
        String filename="bitmap"+".png";
File file1=new File(file,filename);
        try {
            FileOutputStream out=new FileOutputStream(file1);
bitmap.compress(Bitmap.CompressFormat.PNG,100,out);
out.flush();
out.close();
} catch (Exception e) {
            e.printStackTrace();
}

        //把檔案插入到系統圖庫
try {
            MediaStore.Images.Media.insertImage(context.getContentResolver(),file1.getAbsolutePath(),filename,null);
} catch (FileNotFoundException e) {
            e.printStackTrace();
}

        // 通知相簿更新
context.sendBroadcast(new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, Uri.parse("file://" + "/sdcard/namecard/")));
}

    //bitmap轉換成byte陣列
/**
     * bitmap轉換成byte陣列
     *
     * @param bitmap
* @param needRecycle
* @return
*/
public static byte[] bitmapToByteArray(Bitmap bitmap, boolean needRecycle) {
        if (null == bitmap) {
            return null;
}
        if (bitmap.isRecycled()) {
            return null;
}

        ByteArrayOutputStream output = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 100, output);
        if (needRecycle) {
            bitmap.recycle();
}

        byte[] result = output.toByteArray();
        try {
            output.close();
} catch (Exception e) {
        }
        return result;
}
}