您将永远无法确定字符串是否经过URL编码，或者是否应该包含序列%2B.相反，它可能取决于字符串的来源，即它是手工制作的还是来自某些应用程序.

You'll never know for sure if a string is URL-encoded or if it was supposed to have the sequence %2B in it. Instead, it probably depends on where the string came from, i.e. if it was hand-crafted or from some application.

***在字符串中搜索将要编码的字符，否则将不进行编码，如果存在则表示未编码.

Is it better to search the string for characters which would be encoded, which aren't, and if any exist then its not encoded.

我认为这是一种更好的方法，因为它将处理以编程方式完成的事情(假设应用程序不会留下未编码的字符).

I think this is a better approach, since it would take care of things that have been done programmatically (assuming the application would not have left a non-encoded character behind).

在这里会令人困惑的一件事...从技术上讲，如果%应该"被编码在最终值中，则它应该被编码，因为它是一个特殊字符.您可能必须结合使用多种方法来查找应编码的字符，并验证是否在没有找到字符串的情况下成功解码了该字符串.

One thing that will be confusing here... Technically, the % "should be" encoded if it will be present in the final value, since it is a special character. You might have to combine your approaches to look for should-be-encoded characters as well as validating that the string decodes successfully if none are found.