Question

我有quoted-printables的文字。以下是此类文本的示例（来自wikipedia article）：

如果你相信真相= 3Dbeauty，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，它将编码形式解码为chars，例如 = 20 到空格。

更新：感谢The Elite Gentleman，我知道我需要使用QuotedPrintableCodec：

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() );           
    }
}

但是我一直得到以下例外：

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：我找到this question @ SO并了解MimeUtility：

import javax.mail.MessagingException;
import javax.mail.internet.MimeUtility;

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 MessagingException, IOException  
    {
        InputStream is = new ByteArrayInputStream(TXT.getBytes());

            BufferedReader br = new BufferedReader ( new InputStreamReader(  MimeUtility.decode(is, "quoted-printable") ));         
            StringWriter writer = new StringWriter(); 

            String line;
            while( (line = br.readLine() ) != null )
            {
                writer.append(line);
            }
            System.out.println("INPUT:  "  + TXT);
            System.out.println("OUTPUT: " +  writer.toString() );       
    }
    }

然而输出仍然不完美，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？

Answer 1

Apache Commons Codec QuotedPrintableCodec类确实是RFC 1521 Quoted-Printable部分的实现。

更新，您的quoted-printable字符串是错误的，因为维基百科上的示例使用了Soft-line break。

软线休息：

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.

所以你的文字应该如下：

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未实现但是因为完整的引用可打印规范不适合自己很好地进入面向字节[]的编解码器框架。完成编解码器一次可运行的编解码器框架已准备就绪。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入对于那些不需要引用可打印行的应用程序非常方便格式化（规则＃3，＃4，＃5），例如Q codec。

Apache QuotedPrintableCodec有一个bug logged，因为它不支持软换行符。

如何解码可引用的字符（从quotable到char）？

1 个答案: