必要时用于 URL 编码的 Java 库(如浏览器)

Question

如果我将 http://localhost:9000/space test URL 放入 Web 浏览器的地址栏，它会使用 http://localhost:9000/space 调用服务器%20 测试。 http://localhost:9000/specÁÉÍtest 也会被编码为 http://localhost:9000/spec%C3%81%C3%89%C3%8Dtest。

如果将编码后的 URL 放入地址栏(即 http://localhost:9000/space%20test 和 http://localhost:9000/spec%C3%81% C3%89%C3%8Dtest) 它们保持不变(它们不会被双重编码)。

是否有执行此编码的任何 Java API 或库？这些 URL 来自用户，所以我不知道它们是否经过编码。

(如果没有，在输入字符串中搜索 % 是否足够，如果没有找到则进行编码，或者是否有任何特殊情况这不起作用？)

编辑:

URLEncoder.encode("space%20test", "UTF-8") 返回 space%2520test 这不是我想要的，因为它是双重的编码。

编辑 2:

此外，浏览器会处理部分编码的 URL，例如 http://localhost:9000/specÁÉ%C3%8Dtest，嗯，不会对它们进行双重编码。在这种情况下，服务器会收到以下 URL:http://localhost:9000/spec%C3%81%C3%89%C3%8Dtest。与...specÁÉÍtest的编码形式相同。

Answer 1

What every web developer must know about URL encoding

Url Encoding Explained

为什么需要 URL 编码？

The URL specification RFC 1738 specifies that only a small set of characters 
can be used in a URL. Those characters are:

A to Z (ABCDEFGHIJKLMNOPQRSTUVWXYZ)
a to z (abcdefghijklmnopqrstuvwxyz)
0 to 9 (0123456789)
$ (Dollar Sign)
- (Hyphen / Dash)
_ (Underscore)
. (Period)
+ (Plus sign)
! (Exclamation / Bang)
* (Asterisk / Star)
' (Single Quote)
( (Open Bracket)
) (Closing Bracket)

URL 编码是如何工作的？

All offending characters are replaced by a % and a two digit hexadecimal value 
that represents the character in the proper ISO character set. Here are a 
couple of examples:

$ (Dollar Sign) becomes %24
& (Ampersand) becomes %26
+ (Plus) becomes %2B
, (Comma) becomes %2C
: (Colon) becomes %3A
; (Semi-Colon) becomes %3B
= (Equals) becomes %3D
? (Question Mark) becomes %3F
@ (Commercial A / At) becomes %40

简单示例:

import java.util.logging.Level;
import java.util.logging.Logger;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

public class TextHelper {
    private static ScriptEngine engine = new ScriptEngineManager()
        .getEngineByName("JavaScript");

/**
 * Encoding if need escaping %$&+,/:;=?@<>#%
 *
 * @param str should be encoded
 * @return encoded Result 
 */
public static String escapeJavascript(String str) {
    try {
        return engine.eval(String.format("escape(\"%s\")", 
            str.replaceAll("%20", " "))).toString()
                .replaceAll("%3A", ":")
                .replaceAll("%2F", "/")
                .replaceAll("%3B", ";")
                .replaceAll("%40", "@")
                .replaceAll("%3C", "<")
                .replaceAll("%3E", ">")
                .replaceAll("%3D", "=")
                .replaceAll("%26", "&")
                .replaceAll("%25", "%")
                .replaceAll("%24", "$")
                .replaceAll("%23", "#")
                .replaceAll("%2B", "+")
                .replaceAll("%2C", ",")
                .replaceAll("%3F", "?");
    } catch (ScriptException ex) {
        Logger.getLogger(TextHelper.class.getName())
            .log(Level.SEVERE, null, ex);
        return null;
    }
}