Java相当于生成相同输出的JavaScript的encodeURIComponent？

Question

我一直在试验各种Java代码试图想出一些东西,它将编码一个包含引号,空格和"奇异"Unicode字符的字符串,并产生与JavaScript的encodeURIComponent函数相同的输出.

我的折磨测试字符串是:"A"B±"

如果我在Firebug中输入以下JavaScript语句:

encodeURIComponent('"A" B ± "');

- 然后我得到:

"%22A%22%20B%20%C2%B1%20%22"

这是我的小测试Java程序:

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;

public class EncodingTest
{
  public static void main(String[] args) throws UnsupportedEncodingException
  {
    String s = "\"A\" B ± \"";
    System.out.println("URLEncoder.encode returns "
      + URLEncoder.encode(s, "UTF-8"));

    System.out.println("getBytes returns "
      + new String(s.getBytes("UTF-8"), "ISO-8859-1"));
  }
}

- 该计划输出:

URLEncoder.encode returns %22A%22+B+%C2%B1+%22
getBytes returns "A" B ± "

关闭,但没有雪茄!使用Java编码UTF-8字符串的最佳方法是什么,以便它产生与JavaScript相同的输出encodeURIComponent？

编辑:我很快就使用Java 1.4迁移到Java 5.

Answer 1

这是我最终提出的课程:

import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;

/**
 * Utility class for JavaScript compatible UTF-8 encoding and decoding.
 * 
 * @see http://stackoverflow.com/questions/607176/java-equivalent-to-javascripts-encodeuricomponent-that-produces-identical-output
 * @author John Topley 
 */
public class EncodingUtil
{
  /**
   * Decodes the passed UTF-8 String using an algorithm that's compatible with
   * JavaScript's <code>decodeURIComponent</code> function. Returns
   * <code>null</code> if the String is <code>null</code>.
   *
   * @param s The UTF-8 encoded String to be decoded
   * @return the decoded String
   */
  public static String decodeURIComponent(String s)
  {
    if (s == null)
    {
      return null;
    }

    String result = null;

    try
    {
      result = URLDecoder.decode(s, "UTF-8");
    }

    // This exception should never occur.
    catch (UnsupportedEncodingException e)
    {
      result = s;  
    }

    return result;
  }

  /**
   * Encodes the passed String as UTF-8 using an algorithm that's compatible
   * with JavaScript's <code>encodeURIComponent</code> function. Returns
   * <code>null</code> if the String is <code>null</code>.
   * 
   * @param s The String to be encoded
   * @return the encoded String
   */
  public static String encodeURIComponent(String s)
  {
    String result = null;

    try
    {
      result = URLEncoder.encode(s, "UTF-8")
                         .replaceAll("\\+", "%20")
                         .replaceAll("\\%21", "!")
                         .replaceAll("\\%27", "'")
                         .replaceAll("\\%28", "(")
                         .replaceAll("\\%29", ")")
                         .replaceAll("\\%7E", "~");
    }

    // This exception should never occur.
    catch (UnsupportedEncodingException e)
    {
      result = s;
    }

    return result;
  }  

  /**
   * Private constructor to prevent this class from being instantiated.
   */
  private EncodingUtil()
  {
    super();
  }
}

Answer 2

看看实现差异,我看到:

MDCencodeURIComponent():

• 文字字符(正则表达式): [-a-zA-Z0-9._*~'()!]

Java 1.5.0文档URLEncoder:

• 文字字符(正则表达式): [-a-zA-Z0-9._*]
• 空格字符" "转换为加号"+".

基本上,要获得所需的结果,请使用URLEncoder.encode(s, "UTF-8")然后进行一些后处理:

• 替换所有出现的"+"与"%20"
• 将所有出现的"%xx"任何表示替换[~'()!]回其文字对位部分

Answer 3

使用Java 6附带的javascript引擎:

import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;

public class Wow
{
    public static void main(String[] args) throws Exception
    {
        ScriptEngineManager factory = new ScriptEngineManager();
        ScriptEngine engine = factory.getEngineByName("JavaScript");
        engine.eval("print(encodeURIComponent('\"A\" B ± \"'))");
    }
}

产量:%22A%22%20B%20%c2%b1%20%22

情况有所不同,但它更接近你想要的.

Answer 4

我使用java.net.URI#getRawPath(),例如

String s = "a+b c.html";
String fixed = new URI(null, null, s, null).getRawPath();

的价值fixed将是a+b%20c.html,这是你想要的.

对输出进行后处理URLEncoder.encode()将消除应该在URI中的任何优缺点.例如

URLEncoder.encode("a+b c.html").replaceAll("\\+", "%20");

会给你a%20b%20c.html,这将被解释为a b c.html.

Answer 5

我想出了我自己的encodeURIComponent版本，因为发布的解决方案有一个问题，如果字符串中存在一个+，应该编码，它将转换为空格。

所以这是我的课：

import java.io.UnsupportedEncodingException;
import java.util.BitSet;

public final class EscapeUtils
{
    /** used for the encodeURIComponent function */
    private static final BitSet dontNeedEncoding;

    static
    {
        dontNeedEncoding = new BitSet(256);

        // a-z
        for (int i = 97; i <= 122; ++i)
        {
            dontNeedEncoding.set(i);
        }
        // A-Z
        for (int i = 65; i <= 90; ++i)
        {
            dontNeedEncoding.set(i);
        }
        // 0-9
        for (int i = 48; i <= 57; ++i)
        {
            dontNeedEncoding.set(i);
        }

        // '()*
        for (int i = 39; i <= 42; ++i)
        {
            dontNeedEncoding.set(i);
        }
        dontNeedEncoding.set(33); // !
        dontNeedEncoding.set(45); // -
        dontNeedEncoding.set(46); // .
        dontNeedEncoding.set(95); // _
        dontNeedEncoding.set(126); // ~
    }

    /**
     * A Utility class should not be instantiated.
     */
    private EscapeUtils()
    {

    }

    /**
     * Escapes all characters except the following: alphabetic, decimal digits, - _ . ! ~ * ' ( )
     * 
     * @param input
     *            A component of a URI
     * @return the escaped URI component
     */
    public static String encodeURIComponent(String input)
    {
        if (input == null)
        {
            return input;
        }

        StringBuilder filtered = new StringBuilder(input.length());
        char c;
        for (int i = 0; i < input.length(); ++i)
        {
            c = input.charAt(i);
            if (dontNeedEncoding.get(c))
            {
                filtered.append(c);
            }
            else
            {
                final byte[] b = charToBytesUTF(c);

                for (int j = 0; j < b.length; ++j)
                {
                    filtered.append('%');
                    filtered.append("0123456789ABCDEF".charAt(b[j] >> 4 & 0xF));
                    filtered.append("0123456789ABCDEF".charAt(b[j] & 0xF));
                }
            }
        }
        return filtered.toString();
    }

    private static byte[] charToBytesUTF(char c)
    {
        try
        {
            return new String(new char[] { c }).getBytes("UTF-8");
        }
        catch (UnsupportedEncodingException e)
        {
            return new byte[] { (byte) c };
        }
    }
}