有很多场景和需求你需要用到手机设备的唯一标识符。在Android中，各类方法过于单一，它们中的一些可能会返回null，或者由于硬件缺失、权限问题等获取失败。但你总能获得至少一个能用。所以，最好的方法就是通过拼接，或者拼接后的计算出的MD5值来产生一个结果。-There are many scenarios and requirements that you need to use mobile devices unique identifier. In Android, various methods are too simple, some of them may return null, or due to lack of hardware, failed to obtain permission issues. But you can always get at least one. Therefore, the best way is by splicing to produce a result, or the calculated spliced MD5 value.