0

我已将这段代码中的奇怪问题减少到最低限度。该程序将 (int)90000 的 128,000 倍字节写入文件，然后尝试将其读回。

设置 zipped=false 一切都像魅力一样工作 此时一个字节丢失，所有内容都向左移动一个字节（见输出）

...
0 1 95 -112- 这是 int 90,000 的字节码
计数器：496 126937
1 95 -112 0- 这是 int 23,040,000 的字节码
...

这是我想出的代码。我只是不明白为什么它会在一遍又一遍地做同样的事情时突然中断。非常感谢任何帮助/见解/解释者。

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(); }
}
}
4

1 回答 1

0

因此，根据 Jon 的精彩评论......即使流中有更多字节，您也不能依赖 .read(buffer) 填充缓冲区 - 它停在 BufferedOutputStream 包装的 GZIPOutputStream 保存一大块数据的边界处。只需添加另一个读取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++;
        }
于 2017-09-30T00:17:36.153 回答