我在一些单元测试中被这个咬了。
我想使用Inflater解压缩一些 ZLIB 压缩的数据,其中原始数据长度是预先知道的。
这(直截了当)按预期工作
/*
* Decompresses a zlib compressed buffer, with given size of raw data.
* All data is fed and inflated in full (one step)
*/
public static byte[] decompressFull(byte[] comp, int len) throws Exception {
byte[] res = new byte[len]; // result (uncompressed)
Inflater inf = new Inflater();
inf.setInput(comp);
int n = inf.inflate(res, 0, len);
if (n != len)
throw new RuntimeException("didn't inflate all data");
System.out.println("Data done (full). bytes in :" + inf.getBytesRead()
+ " out=" + inf.getBytesWritten()
+ " finished: " + inf.finished());
// done - the next is not needed, just for checking...
//try a final inflate just in case (might trigger ZLIB crc check)
byte[] buf2 = new byte[6];
int nx = inf.inflate(buf2);//should give 0
if (nx != 0)
throw new RuntimeException("nx=" + nx + " " + Arrays.toString(buf2));
if (!inf.finished())
throw new RuntimeException("not finished?");
inf.end();
return res;
}
现在,压缩输入可以以任意大小的块出现。以下代码模拟了压缩输入除了最后 4 个字节外全部输入的情况,然后一次输入一个剩余字节。(据我了解,zlib 流的最后 4 个或 5 个字节不需要解压缩完整数据,但需要它们来检查完整性 - Adler-32 CRC)。
public static byte[] decompressBytexByte(byte[] comp, int len) throws Exception {
byte[] res = new byte[len]; // result (uncompressed)
Inflater inf = new Inflater();
inf.setInput(comp, 0, comp.length - 4);
int n = inf.inflate(res, 0, len);
if (n != len)
throw new RuntimeException("didn't inflate all data");
// inf.setInput(comp, comp.length-4,4);
// !!! works if I uncomment the line befor and comment the next for
for (int p = comp.length - 4; p < comp.length; p++)
inf.setInput(comp, p, 1);
System.out.println("Data done (decompressBytexByte). bytes in :" + inf.getBytesRead()
+ " out=" + inf.getBytesWritten() + " finished: " + inf.finished());
// all data fed... try a final inflate (might -should?- trigger ZLIB crc check)
byte[] buf2 = new byte[6];
int nx = inf.inflate(buf2);//should give 0
if (nx != 0)
throw new RuntimeException("nx=" + nx + " " + Arrays.toString(buf2));
if (!inf.finished())
throw new RuntimeException("not finished?");
inf.end();
return res;
}
好吧,这对我不起作用(Java 1.8.0_181)。充气机没有完成,Adler CRC 校验没有完成,看起来;更多:似乎字节没有被送入充气机。
更奇怪的是:如果在一次调用中输入尾随的 4 个字节,它就可以工作。
你可以在这里试试:https ://repl.it/@HernanJJ/Inflater-Test
当我一次输入整个输入一个字节时,甚至会发生更奇怪的事情:有时该行 int nx= inf.inflate(buf2);//should give 0
返回非零(当所有数据都已经膨胀时)。
这是预期的行为吗?我错过了什么吗?