GZIP解压字符串幻数异常

Question

我正在尝试解压缩一个字符串，但在解压缩时总是出现幻数异常。首先，我正在压缩一个字符串，然后对其进行 base64 编码，然后进行解码和解压缩。代码按调用顺序。

它是一个基于 android 的项目，没有外部依赖项。

编码和解码工作正常。

有人注意到此代码中的错误并告诉我如何解决吗？：

//Compressing a String
public String compress(String s) {
  if(s == null || s.length() == 0) { return string; }

  try {
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    GZIPOutputStream gzip = new GZIPOutputStream(out);
    gzip.write(s.getBytes("UTF-8"));
    gzip.close();
    return out.toString("UTF-8");
  } catch (Exception e) {
    e.printStackTrace();
  }
}
//Encode to Base64
public String encodeBase64(String s) {
  return Base64.encodeToString(s.getBytes("UTF-8"), Base64.NO_WRAP);
}

//Decode Base64
public String decodeBase64(String s) {
  return new String(Base64.decode(s, Base64.NO_WRAP), "UTF-8");
}

public String decompress(String s) {
  if(s == null || s.length() == 0) {
    return s;
  }
  byte[] ba = s.getBytes("UTF-8");
  byte[] buffer = new byte[1024];

  try {
    ByteArrayOutputStream out = new ByteArrayOutputStream(ba.length);
    ByteArrayInputStream in = new ByteArrayInputStream(ba);
    GZIPInputStream gzip = new GZIPInputStream(in); // Magic Number Exception occures here
    int len;
    while((len = gzip.read(buffer)) > 0) {
      out.write(buffer,0 ,len);
    }
    gzip.close();
    out.close();
    return out.toString("UTF-8");
  } catch (Exception e) {
    e.printStackTrace;
  } 
}

更新：

我用应该在 android 项目中可用的方法和调用方法制作了一个测试类：

import android.util.Base64;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.UnsupportedEncodingException;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;

public class CompressTest {

    public static final String message = "Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet.   \n" +
            "\n" +
            "Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat.   \n" +
            "\n" +
            "Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat. Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi.   \n" +
            "\n" +
            "Nam liber tempor cum soluta nobis eleifend option congue nihil imperdiet doming id quod mazim placerat facer possim assum. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat.   \n" +
            "\n" +
            "Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis.   \n" +
            "\n" +
            "At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, At accusam aliquyam diam diam dolore dolores duo eirmod eos erat, et nonumy sed tempor et et invidunt justo labore Stet clita ea et gubergren, kasd magna no rebum. sanctus sea sed takimata ut vero voluptua. est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat.   \n" +
            "\n" +
            "Consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus.   \n" +
            "\n" +
            "Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet. Lorem ipsum dolor sit amet, consetetur sadipscing elitr, sed diam nonumy eirmod tempor invidunt ut labore et dolore magna aliquyam erat, sed diam voluptua. At vero eos et accusam et justo duo dolores et ea rebum. Stet clita kasd gubergren, no sea takimata sanctus est Lorem ipsum dolor sit amet.   \n" +
            "\n" +
            "Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat.   \n" +
            "\n" +
            "Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat. Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi.   \n" +
            "\n" +
            "Nam liber tempor cum soluta nobis eleifend option congue nihil imperdiet doming id quod mazim placerat facer possim assum. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo";

    //Compressing a String
    public static String compress(String s) {
        if(s == null || s.length() == 0) { return s; }

        try {
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            GZIPOutputStream gzip = new GZIPOutputStream(out);
            gzip.write(s.getBytes("UTF-8"));
            gzip.close();
            return out.toString("UTF-8");
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
    //Encode to Base64
    public static String encodeBase64(String s) throws UnsupportedEncodingException {
        return Base64.encodeToString(s.getBytes("UTF-8"), Base64.NO_WRAP);
    }

    //Decode Base64
    public static String decodeBase64(String s) throws UnsupportedEncodingException {
        return new String(Base64.decode(s, Base64.NO_WRAP), "UTF-8");
    }

    public static String decompress(String s) throws UnsupportedEncodingException {
        if(s == null || s.length() == 0) {
            return s;
        }
        byte[] ba = s.getBytes("UTF-8");
        byte[] buffer = new byte[1024];

        try {
            ByteArrayOutputStream out = new ByteArrayOutputStream(ba.length);
            ByteArrayInputStream in = new ByteArrayInputStream(ba);
            GZIPInputStream gzip = new GZIPInputStream(in); // Magic Number Exception occures here
            int len;
            while((len = gzip.read(buffer)) > 0) {
                out.write(buffer,0 ,len);
            }
            gzip.close();
            out.close();
            return out.toString("UTF-8");
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
}

这里是电话：

try {
            String s = CompressTest.message;
            System.out.println("-----------------Message is:-----------------");
            s = CompressTest.compress(s);
            System.out.println("-----------------Compression is:-----------------");
            System.out.println(s);

            s = CompressTest.encodeBase64(s);
            System.out.println("-----------------Base64 Encode is:-----------------");
            System.out.println(s);

            s = CompressTest.decodeBase64(s);
            System.out.println("-----------------Base64 Decode is:-----------------");
            System.out.println(s);

            s = CompressTest.decompress(s);
            System.out.println("-----------------decompressed is:-----------------");
            System.out.println(s);
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }

此外，我用上面的测试类中的数据进行了测试。

消息：见上面代码压缩： ��Mn��0��9��vtS��cq��L��8MN��7��\��A[��"��- Y$��h��TI��c��D��R��i’N��74��K7��c��n��I��(��l��Dk*��h>j� ��:E,I��%>d&��h��X@��%��؍��t��(��y��N_��B��ʲ��\��, m�3D��L�l’�P%o��:?hbG[t9Se1��6��-��)#UserO�TT��b�y��a ��{P�2N��m��u5�%A�$ϐ�EN�@�y�r��o�d�[��"��mlVrM��G�9��p <��?f"'��h9��-��o?c��,��/��/��O<��L5Ntl.9' �$O�a �5f�>8�/� C ��i=v_Q��4��2��Q��

编码：

H++/vQgAAAAAAAAA77+9TW7vv70wEO+/ve+/vTnvv70c77+977+9He+/vXYZdFPvv70AY3Hvv71M77+9H++/ve+/vThNTu+/vTfvv71c77+9QVvvv73vv70iDu+/ve+/vS1ZJO+/vW/vv71o77+9VEnvv71j77+9RO+/ve+/vVLvv71pJ07vv703NO+/vdykSzfvv73vv70BYwbvv70H77+ 977+977+9bu+/vUnvv73vv73vv70o77+9bO+/vURrKu+/ve+/ve+/vRHvv71oPmrvv73vv73vv706Rd6hCEnvv70LCCU+ZCbvv73vv71o77+9WEAq77+977+9Je+/vdiN77+9dO+/ve+/vSjvv73vv73vv73vv715GO+/ve+/ve+/vU5f77+977+9Qu+/vcqy77+977+9XO+/ ve+/ve+/vSxt77+9M0Tvv70A77+9TA/vv70CHWwn77+9UCVv77+9Fu+/ve+/vTo/aGI8b++/ve+/vW7vv73vv70677+977+977+977+9D++/vVZOK++/vX/vv71EdHPvv73RtBEbLEJXJO+/vTDv++71qcDTvv73vv71M+ /vWnvv705Whzvv71zFx/vv73vv73vv70177+9LxHvv71UZu+/ve+/ve+/ve+/vX0177+977+9VBbvv73vv73vv71iB++/vU7vv71iZO+/ve+/vVHvv73vv70/Qe+/vWcqCS7vv71aJywlKO+/ve+/vSFra++/ve+/vdGUdu+/vXPvv73vv73vv73vv700QVscMXcUfHnvv70aKUjvv73vv71e77+9YHDvv70+FyUQ77+9SlhfK++/ve+/ vQzvv70d77+977+977+977+9c3heZwfvv73Juu+/ve+/vWltU++/vTQPF++/vUHvv71fRmdJzpTvv70+77+90qMv77+977+977+977+9YCfvv70wJe+/vSNuOW3vv71FQ++/vdarBe+/vW9SB0UU77+977+9TG4uDe+/ve+/vRDvv70Makfvv73vv70F77+977+9PkdbdDlTZR0x77+977+ 9Nu +/vQTvv73vv73vv73vv70t77+9Ge+/vSkj3pJP77+9VFTvv73vv73vv73vv70BYu+/vXnvv70Y77+977+9YR3vv73vv717UO+/vTJO77+977+9be+/ve+/ve+/vR51Ne+/vSVB77+9DCTPkAbvv71FThLvv71A77+9GHnvv71y77+977+9bxrvv71k77+9W++/ve+/ve+/vSLvv73vv73vv71tbFZyTRvvv73vv71H77+9Od2e77+977+ 9cDzvv70/ZiInF++/vWgBOe+/ve+/ve+/ve+/ve+/ve+/ve+/vRkt77+977+9bz9j77+977+9LO+/vS/vv73vv70q77+9L++/vU8877+9BgDvv73vv73vv70E77+977+9TDVOdGzvv705J++/vSRP77+977+9YQ3vv701Zu+/ve+ /vT4477+9L++/vQpjDe+/ve+/vWk9dl9R77+977+977+9NO+/ve+/ve+/vTLvv70e77+977+977+977+977+9He+/ve+/vVEY77+9FwAA

解码：

��Mn��0��9��vtS��cq��L��8MN��7��\��A[� ��"��-Y$��o��TI��c��D��R��i'N��74��k7��c��n��I��(��l��Dk*�� h>j��:E,I��%>d&��h��X@��%��؍��t��(��y��N_��B��ʲ�� \��,m��3D��L��l'��P%o��:?hbG[t9Se1��6��-��)#UserO��TT��b�� y��a��{P��2N��m��u5��%A.$ϐ��EN��@y��r��o��[��"��mlVrM��G ��9j��p<��?f"'��h9��-��o?c��,��/��/��O<�� L5Ntl�9”�$O�a �5f�>8�/� C ��i=v_Q��4��2��Q��

这里不是很明显，但我比较了编码前和解码后的压缩，它看起来像这样：

开头少了一个字符，其他都没问题。所以这可能是数据头的一部分，其中包含 gzip 格式的信息。我稍后会尝试手动添加，post 结果

解决方案

对于所有感兴趣的人，我如何按照 Teemu Ilmonen 的建议在此处更改代码的 bytearray 版本的方法：

//Compressing a String
    public static byte[] compress(String s) {
        if(s == null || s.length() == 0) { return null; }

        try {
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            GZIPOutputStream gzip = new GZIPOutputStream(out);
            gzip.write(s.getBytes("UTF-8"));
            gzip.close();
            return out.toByteArray();
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
    //Encode to Base64
    public static String encodeBase64(byte[]  array) throws UnsupportedEncodingException {
        return Base64.encodeToString(array, Base64.NO_WRAP);
    }

    //Decode Base64
    public static byte[] decodeBase64(String s) throws UnsupportedEncodingException {
        return Base64.decode(s, Base64.NO_WRAP);
    }

    public static String decompress(byte[] array) throws UnsupportedEncodingException {
        if(array == null || array.length == 0) {
            return null;
        }
        byte[] buffer = new byte[1024];

        try {
            ByteArrayOutputStream out = new ByteArrayOutputStream(array.length);
            ByteArrayInputStream in = new ByteArrayInputStream(array);
            GZIPInputStream gzip = new GZIPInputStream(in); // Magic Number Exception occures here
            int len;
            while((len = gzip.read(buffer)) > 0) {
                out.write(buffer,0 ,len);
            }
            gzip.close();
            out.close();
            return out.toString("UTF-8");
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

Answer 1

一旦你用 gzip 压缩了一些东西，你应该不再将它转换成字符串。您可能在混淆那里的内容。你应该使用 byte[] 代替：

return out.toByteArray();

Answer 2

您需要按以下顺序执行：

将字符串转换为 Base64
使用 GZip 压缩 Base64 字符串
解压缩 GZip 流。
将 Base64 解码为纯文本。

您收到异常是因为您正在尝试解压缩 Base64 字符串而不是 GZip 流

GZIP解压字符串幻数异常

GZIP Decompressing String Magic Number Exception

java

compression

android

gzip