如何在 Java 中进行 URL 解码? [英] How to do URL decoding in Java?

问题描述

在 Java 中，我想转换这个:

https%3A%2F%2Fmywebsite%2Fdocs%2Fenglish%2Fsite%2Fmybook.do%3Frequest_type

为此:

https://mywebsite/docs/english/site/mybook.do&request_type

这是我目前所拥有的:

class StringUTF 
{
    public static void main(String[] args) 
    {
        try{
            String url = 
               "https%3A%2F%2Fmywebsite%2Fdocs%2Fenglish%2Fsite%2Fmybook.do" +
               "%3Frequest_type%3D%26type%3Dprivate";

            System.out.println(url+"Hello World!------->" +
                new String(url.getBytes("UTF-8"),"ASCII"));
        }
        catch(Exception E){
        }
    }
}

但它不起作用.这些 %3A 和 %2F 格式是什么，我该如何转换它们?

But it doesn't work right. What are these %3A and %2F formats called and how do I convert them?

推荐答案

这与 UTF-8 或 ASCII 等字符编码没有任何关系.您拥有的字符串是URL 编码.这种编码与字符编码完全不同.

This does not have anything to do with character encodings such as UTF-8 or ASCII. The string you have there is URL encoded. This kind of encoding is something entirely different than character encoding.

试试这样的:

try {
    String result = java.net.URLDecoder.decode(url, StandardCharsets.UTF_8.name());
} catch (UnsupportedEncodingException e) {
    // not going to happen - value came from JDK's own StandardCharsets
}

Java 10 为 API 添加了对 Charset 的直接支持，这意味着无需捕获 UnsupportedEncodingException:

Java 10 added direct support for Charset to the API, meaning there's no need to catch UnsupportedEncodingException:

String result = java.net.URLDecoder.decode(url, StandardCharsets.UTF_8);

请注意，字符编码(例如 UTF-8 或 ASCII)决定了字符到原始字节的映射.有关字符编码的详细介绍，请参阅这篇文章.

Note that a character encoding (such as UTF-8 or ASCII) is what determines the mapping of characters to raw bytes. For a good intro to character encodings, see this article.

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