如何检查字符串是否为连接的base64 codeD或不 [英] How to check whether the string is base64 encoded or not

问题描述

我要脱code为Base64 EN codeD字符串，然后将其存储在我的分贝。如果输入不带采用base64 code，则需要抛出一个错误。我如何检查是否字符串是的base64 ENO codeD？

I want to decode the base64 encoded string, then store it in my db. If the input does not base64 encode, need to throw an error. How can I check if the string was base64 enocoded?

推荐答案

您可以使用下面的正前pression检查一个字符串的base64 EN codeD或不：

You can use the following regular expression to check if a string is base64 encoded or not:

^([A-Za-z0-9+/]{4})*([A-Za-z0-9+/]{4}|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{2}==)$

在base64编码，字符集是 [A-Z，A-Z，0-9和+ /] 。如果剩下的长度小于4，字符串被填充为=字符。

In base64 encoding, the character set is [A-Z, a-z, 0-9, and + /]. If the rest length is less than 4, the string is padded with '=' characters.

^（[A-ZA-Z0-9 + /] {4}）* 表示字符串以0个或更多的base64组开始。

^([A-Za-z0-9+/]{4})* means the string starts with 0 or more base64 groups.

（[A-ZA-Z0-9 + /] {4} | [A-ZA-Z0-9 + /] {3} = | [A-ZA-Z0-9 + /] {2} ==）$ 表示字符串结尾三种形式： [A-ZA-Z0-9 + /] {4} ， [A-ZA-Z0-9 + /] {3} = 或 [A-ZA-Z0-9 + /] {2} == 。

([A-Za-z0-9+/]{4}|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{2}==)$ means the string ends in one of three forms: [A-Za-z0-9+/]{4}, [A-Za-z0-9+/]{3}= or [A-Za-z0-9+/]{2}==.

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