从Uri获得图片真实路径

public static String getRealPathFromURI(Uri uri, ContentResolver resolver) {

		String[] projection = { MediaStore.Images.Media.DATA };
		Cursor cursor = resolver.query(uri, projection, null, null, null);
		int column_index = cursor
				.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
		cursor.moveToFirst();
		String str = cursor.getString(column_index);
		cursor.close();
		return str;
	}