Java 如何解码可引用字符（从可引用到字符）？

我有一条短信。以下是此类文本的示例（来自a）：

如果你相信真理=美，那么肯定=20=
数学是哲学中最美丽的分支

我正在寻找一个Java类，它将编码的表单解码为字符，例如，=20到一个空格

更新：感谢Elite先生，我知道我需要使用QuotedPrintable编解码器：

import org.apache.commons.codec.DecoderException;
import org.apache.commons.codec.net.QuotedPrintableCodec;
import org.junit.Test;

public class QuotedPrintableCodecTest { 
private static final String TXT =  "If you believe that truth=3Dbeauty, then surely=20=mathematics is the most beautiful branch of philosophy.";

    @Test
    public void processSimpleText() throws DecoderException
    {
        QuotedPrintableCodec.decodeQuotedPrintable( TXT.getBytes() );           
    }
}   

但是，我不断得到以下例外情况：

org.apache.commons.codec.DecoderException: Invalid URL encoding: not a valid digit (radix 16): 109
    at org.apache.commons.codec.net.Utils.digit16(Utils.java:44)
    at org.apache.commons.codec.net.QuotedPrintableCodec.decodeQuotedPrintable(QuotedPrintableCodec.java:186)

我做错了什么

更新2：我发现并了解：

但是输出仍然不完美，它包含“=”：

INPUT:  If you believe that truth=3Dbeauty, then surely=20= mathematics is the most beautiful branch of philosophy.
OUTPUT: If you believe that truth=beauty, then surely = mathematics is the most beautiful branch of philosophy.

现在我做错了什么？

类所做的是RFC1521引用的可打印部分的实现

---

更新，您引用的可打印字符串是错误的，因为Wikipedia上的示例使用了软换行符

软换行符：

Rule #5 (Soft Line Breaks): The Quoted-Printable encoding REQUIRES
      that encoded lines be no more than 76 characters long. If longer
      lines are to be encoded with the Quoted-Printable encoding, 'soft'
      line breaks must be used. An equal sign as the last character on a
      encoded line indicates such a non-significant ('soft') line break
      in the encoded text. Thus if the "raw" form of the line is a
      single unencoded line that says:

          Now's the time for all folk to come to the aid of
          their country.

      This can be represented, in the Quoted-Printable encoding, as

          Now's the time =
          for all folk to come=
           to the aid of their country.

      This provides a mechanism with which long lines are encoded in
      such a way as to be restored by the user agent.  The 76 character
      limit does not count the trailing CRLF, but counts all other
      characters, including any equal signs.

因此，您的文本应如下所示：

private static final String CRLF = "\r\n";
private static final String S = "If you believe that truth=3Dbeauty, then surely=20=" + CRLF + "mathematics is the most beautiful branch of philosophy.";

Javadoc明确指出：

引用的可打印规范的规则#3、#4和#5未实施 然而，因为完整引用的可打印规范本身并不适用 深入到面向字节[]的编解码器框架中。完成一次编解码器 蒸汽编解码器框架已经准备就绪。背后的动机 以部分形式提供编解码器是因为它已经可以进来了 适用于不需要引用可打印行的应用程序 格式化（规则#3、#4、#5），例如Q编解码器

---

还有一个Apache QuotedPrintableCodec，因为它不支持软换行。

谢谢你的回答，不幸的是，当我试图从Wikipedia页面解码示例时，我遇到了一个异常。@Skarab，除非你向我们展示代码&异常堆栈跟踪，否则你不能认为我的答案是错误的，因为它引发了一个异常。您要求提供一个解码可引用字符的类&我确实向您展示了。@Skarab，我更新了我的帖子到您的家庭作业练习中。我现在应该期望+1:）

private static final String CRLF = "\r\n";
private static final String S = "If you believe that truth=3Dbeauty, then surely=20=" + CRLF + "mathematics is the most beautiful branch of philosophy.";