使用PHP的base64_decode解码返回false

Question

【遇到的问题】 尝试使用 PHP 的 base64_decode 函数来解码使用 Base64 编码的邮件内容，可是发现有些邮件会返回 false 。据我测试，似乎将含有非 Base64 编码的部分删除后就能正常解码了，可是根据文档说明—— string base64_decode ( string $data [, bool $strict = false ] ) 当设置 strict 为 TRUE 时，一旦输入的数据超出了 base64 字母表，将返回 FALSE。 否则会静默丢弃无效的字符吗？ 我要解码含非编码内容的邮件又该怎么操作？ 【相关代码】 ●要解码的邮件内容示例。只有删掉头尾的那些“------=_Part_…”才能解码成功，否则返回 false 。 <?php $str='------=_Part_52_1608986047.1312859369078 Content-Type: multipart/alternative; boundary="----=_Part_53_1114408905.1312859369078" ------=_Part_53_1114408905.1312859369078 Content-Type: text/plain; charset="gb18030" Content-Transfer-Encoding: base64 1eLKx9K7t+JIVE1MuPHKvdPKvP6jrMfrx9C7u7W9SFRNTMrTzbw ------=_Part_53_1114408905.1312859369078 Content-Type: text/html;charset=UTF-8 Content-Transfer-Encoding: base64 PG1ldGEgY2hhcnNldD0iVVRGLTgiIC8+PHRhYmxlIGFsaWduPSJjZW50ZXIiIHN0eWxlPSJmb250 LWZhbWlseTpNaWNyb3NvZnQgWWFIZWksU2ltc3VuO3dpZHRoOjc1MHB4O3RhYmxlLWxheW91dDpm aXhlZDsiICBiZ2NvbG9yPSIjZmZmZmZmIiBjZWxscGFkZGluZz0iMCIgY2VsbHNwYWNpbmc9IjAi 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Answer 1

不是base64怎么解码。。。

Answer 2

你的$str变量，明显是需要先解析，再解码的。
如果我没猜错的话，原文应该是按照换行符来切割各个部分的，其中Content-Transfer-Encoding标识了编码格式，正文才是需要解码的字符串。
建议你先分隔各个部分，再解码。