话不多说贴代码：

public class ContentUtil {

    /**
     * 根据图片的Uri获取图片的绝对路径(适配多种API)
     *
     * @return 如果Uri对应的图片存在, 那么返回该图片的绝对路径, 否则返回null
     */
    public static String getRealPathFromUri(Context context, Uri uri) {
        int sdkVersion = Build.VERSION.SDK_INT;
        if (sdkVersion < 11) return getRealPathFromUri_BelowApi11(context, uri);
        if (sdkVersion < 19) return getRealPathFromUri_Api11To18(context, uri);
        else return getRealPathFromUri_AboveApi19(context, uri);
    }

    /**
     * 适配api19以上,根据uri获取图片的绝对路径
     */
    @TargetApi(Build.VERSION_CODES.KITKAT)
    private static String getRealPathFromUri_AboveApi19(Context context, Uri uri) {
        String filePath = null;
        String wholeID = DocumentsContract.getDocumentId(uri);

        // 使用':'分割
        String id = wholeID.split(":")[1];

        String[] projection = {MediaStore.Images.Media.DATA};
        String selection = MediaStore.Images.Media._ID + "=?";
        String[] selectionArgs = {id};

        Cursor cursor = context.getContentResolver().query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,//
                projection, selection, selectionArgs, null);
        int columnIndex = cursor.getColumnIndex(projection[0]);
        if (cursor.moveToFirst()) filePath = cursor.getString(columnIndex);
        cursor.close();
        return filePath;
    }

    /**
     * 适配api11-api18,根据uri获取图片的绝对路径
     */
    private static String getRealPathFromUri_Api11To18(Context context, Uri uri) {
        String filePath = null;
        String[] projection = {MediaStore.Images.Media.DATA};
        CursorLoader loader = new CursorLoader(context, uri, projection, null, null, null);
        Cursor cursor = loader.loadInBackground();

        if (cursor != null) {
            cursor.moveToFirst();
            filePath = cursor.getString(cursor.getColumnIndex(projection[0]));
            cursor.close();
        }
        return filePath;
    }

    /**
     * 适配api11以下(不包括api11),根据uri获取图片的绝对路径
     */
    private static String getRealPathFromUri_BelowApi11(Context context, Uri uri) {
        String filePath = null;
        String[] projection = {MediaStore.Images.Media.DATA};
        Cursor cursor = context.getContentResolver().query(uri, projection, null, null, null);
        if (cursor != null) {
            cursor.moveToFirst();
            filePath = cursor.getString(cursor.getColumnIndex(projection[0]));
            cursor.close();
        }
        return filePath;
    }


}