GZIPOutputStream/GZIPInputStream中的奇怪行为

Question

我已经将这个代码中的奇怪问题降到了最低限度。此程序将(int)90000的字节写入文件中的128,000倍，然后尝试将其读取回文件中。

设置zipped=false，一切都像魅力集zipped=true一样工作，一切都像符咒一样工作，直到第496块1024字节。这时，一个字节丢失了，所有东西都向左移动了一个字节(参见输出)。

..。

0 1 95 -112-这是int 90,000的字节码

柜台: 496 126937

1 95 -112 0-这是int 23,040,000的字节码

..。

这就是我想出来的密码。我只是不明白为什么它突然在重复做同样的事情的过程中突然中断。任何帮助/见解/解释者都非常感激。

public class TestApp7 {

static final boolean    zipped = true;
static File             theFile = null;

private static void writeZipData() throws Exception {
    FileOutputStream fos = new FileOutputStream(theFile);
    BufferedOutputStream bos = null;
    if (zipped) {
        GZIPOutputStream gzout = new GZIPOutputStream(fos);
        bos = new BufferedOutputStream(gzout);
    } else 
        bos = new BufferedOutputStream(fos);
    byte[] bs9 = RHUtilities.toByteArray((int)90000);
    for (int i=0; i<128000; i++)
        bos.write(bs9);
    bos.flush();
    bos.close();
}

private static void readZipData() throws Exception {
    byte[] buf = new byte[1024];
    int chunkCounter = 0;
    int intCounter = 0;
    FileInputStream fin = new FileInputStream(theFile);
    int rdLen = 0;
    if (zipped) {
        GZIPInputStream gin = new GZIPInputStream(fin);
        while ((rdLen = gin.read(buf)) != -1) {
            System.out.println("Counters: " + chunkCounter + " " + intCounter);
            for (int i=0; i<rdLen/4; i++) {
                byte[] bs = Arrays.copyOfRange(buf,(i*4),((i+1)*4));
                intCounter++;
                System.out.print(bs[0] + " " + bs[1] + " " + bs[2] + " " + bs[3]);
            }
            chunkCounter++;
        }
        gin.close();
    } else {
        while ((rdLen = fin.read(buf)) != -1) {
            System.out.println("Counters: " + chunkCounter + " " + intCounter);
            for (int i=0; i<rdLen/4; i++) {
                byte[] bs = Arrays.copyOfRange(buf,(i*4),((i+1)*4));
                intCounter++;
                System.out.print(bs[0] + " " + bs[1] + " " + bs[2] + " " + bs[3]);
            }
            chunkCounter++;
        }
    }
    fin.close();
}

public static void main(String args[]) {
    try {
        if (zipped)
            theFile = new File("Test.gz");
        else
            theFile = new File("Test.dat");
        writeZipData();
        readZipData();
    } catch (Throwable e) { e.printStackTrace(); }
}
}

Answer 1

基于乔恩的精彩评论..。即使流中有更多字节，也不能依赖.read(缓冲区)填充缓冲区--它停在BufferedOutputStream包装的GZIPOutputStream保存数据块的边界处。只需添加另一个读以超出边界并完成块。

        while ((rdLen = gin.read(buf)) != -1) {
            if (rdLen<chunksize) {
                byte[] missBytes = new byte[chunksize-rdLen];
                int rdLine_miss = 0;
                if ((rdLine_miss = gin.read(missBytes)) > 0)
                    System.arraycopy(missBytes,0,buf,rdLen,rdLine_miss);
                rdLen += rdLine_miss;
            }
            for (int i=0; i<rdLen/4; i++) {
                byte[] bs = Arrays.copyOfRange(buf,(i*4),((i+1)*4));
                intCounter++;
                System.out.println(bs[0] + " " + bs[1] + " " + bs[2] + " " + bs[3] + " ");
            }
            chunkCounter++;
        }