Question

我正在尝试使用Deflater和InflaterOutputStream压缩和解压缩一些字节数据。

问题在于压缩似乎有效（我不是确保即使我有随机测试数据，压缩数据总是相同的）。但减压根本没有回报。

我做错了什么？

我的控制台输出：

测试数据：D8A8E00821608F227AE473774E177216

压缩数据：789C

解压缩数据：

我的节目：

SecureRandom random = new SecureRandom();
byte[] testdata = new byte[16];
random.nextBytes(testdata);
System.out.println("Test data: " + DatatypeConverter.printHexBinary(testdata));

byte[] compressed = null;
try (ByteArrayOutputStream buffer = new ByteArrayOutputStream())
{
   try (DeflaterOutputStream stream = new DeflaterOutputStream(buffer))
   {
      stream.write(testdata);
      stream.flush();
      compressed = buffer.toByteArray();
      System.out.println("Compressed data: " + DatatypeConverter.printHexBinary(compressed));
   }
}
catch (IOException e)
{
   System.out.println("IOException during compression.");
}

byte[] decompressed = null;
try (ByteArrayOutputStream buffer = new ByteArrayOutputStream())
{
   try (InflaterOutputStream stream = new InflaterOutputStream(buffer))
   {
      stream.write(compressed);
      stream.flush();
      decompressed = buffer.toByteArray();
      System.out.println("Decompressed data: " + DatatypeConverter.printHexBinary(decompressed));
   }
}
catch (IOException e)
{
   System.out.println("IOException during decompression.");
}

Answer 1

问题是你只是刷新流 - 这并不一定意味着没有更多数据可以来，这会影响解压缩。

如果您将flush()两次调用都更改为close()，则会看到您收到相应的数据......或者当您使用try-with-resources语句时，让它关闭内部流，并等到那之后调用toByteArray：

try (ByteArrayOutputStream buffer = new ByteArrayOutputStream())
{
   try (DeflaterOutputStream stream = new DeflaterOutputStream(buffer))
   {
      stream.write(testdata);
   }
   compressed = buffer.toByteArray();
   System.out.println("Compressed data: " + Arrays.toString(compressed));
}
catch (IOException e)
{
   System.out.println("IOException during compression.");
}

（解压缩时也一样。）

Java通缩/通胀流如何运作？

1 个答案: