Question

我正在使用gzip压缩字符串，然后解压缩结果，但是我得到以下异常，为什么？

 output:
Exception in thread "main" java.util.zip.ZipException: oversubscribed dynamic bit lengths tree
 at java.util.zip.InflaterInputStream.read(Unknown Source)
 at java.util.zip.GZIPInputStream.read(Unknown Source)
 at Test.main(Test.java:25)

public class Test {
 public static void main(String[]args) throws IOException{
  String s="helloworldthisisatestandtestonlydsafsdafdsfdsafadsfdsfsdfdsfdsfdsfdsfsadfdsfdasfassdfdfdsfdsdssdfdsfdsfd";
  byte[]bs=s.getBytes();
  ByteArrayOutputStream outstream = new ByteArrayOutputStream();

  GZIPOutputStream gzipOut = new GZIPOutputStream(outstream);
  gzipOut.write(bs);
  gzipOut.finish();
  String out=outstream.toString();
  System.out.println(out);
  System.out.println(out.length());

  ByteArrayInputStream in = new ByteArrayInputStream(out.getBytes());
  GZIPInputStream gzipIn=new GZIPInputStream(in);
  byte[]uncompressed = new byte[100000];
  int len=10, offset=0, totalLen=0;
  while((len = gzipIn.read(uncompressed, offset, len)) >0){ // this line
   offset+=len;
   totalLen+=len;
  }

  String uncompressedString=new String(uncompressed,0,totalLen);
  System.out.println(uncompressedString);
 }
}

Answer 1

根据this page，可能的原因是您尝试阅读的ZIP文件已损坏。（我知道这与你的情况并不完全匹配......但我确信异常消息是指示性的。）

在您的情况下，问题是您正在将gzip流从字节数组转换为String，然后再转换回字节数组。这几乎肯定是一个有损操作，导致GZIP流损坏。

如果要将任意字节数组转换为字符串形式并返回，则需要使用为此目的设计的字符串编码格式之一;例如BASE64。

或者，只需更改此内容：

    String out = outstream.toString();
    ByteArrayInputStream in = new ByteArrayInputStream(out.getBytes());

到此：

    byte[] out = outstream.toByteArray();
    ByteArrayInputStream in = new ByteArrayInputStream(out);

java.util.zip.ZipException：超额订阅动态位长度树

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