java - 为什么 Java/Linux 在文件末尾附加 0xa？

Question

这个问题已经有答案了:

Difference between CR LF, LF and CR line break types (10 个回答)

已关闭 8 年前。

我正在使用 FileOutputStream 写入文件，我注意到十六进制似乎包含终止 0x0a 。这是文件的输出:

0000000: d100 0b00 0000 4865 6c6c 6f20 776f 726c  ......Hello worl
0000010: 6429 0043 0500 0000 7072 696e 740a       d).C....print.

(Note hex code comes from vim on Osx Yosimite x64)

请注意，文件以 0x0a 结尾。这是 Linux 的东西(比如某种 EOF 字符)还是 java/FileOutputStream追加字符？

编辑:代码

public class FileImageOpcodeRenderer implements OpCodeRenderer, AutoCloseable {
  private final FileOutputStream stream;
  private final Iterable<OpCode> opcodes;
  private final List<Byte> data = new ArrayList<>();

  public FileImageOpcodeRenderer(Iterable<OpCode> opcodes, String path) {
    this.opcodes = opcodes;
    try {
      this.stream = new FileOutputStream(path);
    } catch (IOException ex) {
      ex.printStackTrace();

      throw new CompilerException("Unable to open output file");
    }
  }

  public void save() throws Exception {
    List<Byte> renderedContent = renderOpCodes();
    byte[] content = toArray(renderedContent);
    stream.write(content, 0, content.length);
  }

  private List<Byte> renderOpCodes() {
    for (OpCode opCode : opcodes) {
      writeInt8(null, opCode.opNumber());
      opCode.render(this);
    }

    return this.data;
  }

  private byte[] toArray(List<Byte> data) {
    byte[] content = new byte[data.size()];

    for (int index = 0; index < data.size(); index++) {
      content[index] = data.get(index);
    }

    return content;
  }

  @Override
  public void writeInt8(String label, int value) {
    data.add((byte)value);
  }

  @Override
  public void writeInt16(String label, int value) {
    writeInt8(null, (byte)(value & 0xFF));
    writeInt8(null, (byte)((value >> 8) & 0xFF));
  }

  @Override
  public void writeInt32(String label, int value) {
    writeInt8(null, (byte)(value & 0xFF));
    writeInt8(null, (byte)((value >> 8) & 0xFF));
    writeInt8(null, (byte)((value >> 16) & 0xFF));
    writeInt8(null, (byte)((value >> 24) & 0xFF));
  }

  @Override
  public void writeInt64(String label, long value) {
    writeInt8(null, (byte)(value & 0xFF));
    writeInt8(null, (byte)((value >> 8) & 0xFF));
    writeInt8(null, (byte)((value >> 16) & 0xFF));
    writeInt8(null, (byte)((value >> 24) & 0xFF));
    writeInt8(null, (byte)((value >> 32) & 0xFF));
    writeInt8(null, (byte)((value >> 40) & 0xFF));
    writeInt8(null, (byte)((value >> 48) & 0xFF));
    writeInt8(null, (byte)((value >> 56) & 0xFF));
  }

  @Override
  public void writeString(String label, String value) {
    writeInt32(null, value.length());
    for (byte letter : value.getBytes()) {
      System.out.println((int)letter);
      writeInt8(null, letter);
    }
  }

  @Override
  public void close() throws Exception {
    stream.close();
  }
 }

我什至正在查看 save 中的原始字节它以 0x74 结尾，不是0x0a .

更新:摩尔代码:

所以我只是编写了这段代码来用 C++ 加载文件:

int main() {
    int fd = open("/Users/sircodesalot/Desktop/image.vbaj", O_RDONLY);

    char buffer[256] { };
    int amout = read(fd, buffer, 256);

    cout << amout << endl;

    for (int index = 0; index != 256; ++index) {
        if (index > 0 && (index % 10 == 0)) cout << endl;
        cout << hex << (int)buffer[index] << " ";
    }

    close(fd);
}

输出:

29
ffffffd1 0 b 0 0 0 48 65 6c 6c 
6f 20 77 6f 72 6c 64 29 0 43 
5 0 0 0 70 72 69 6e 74 0 
0 0 0 0 0 0 0 0 0 0
... (rest of the 256 byte buffer)

看吧，不0xa ？这有什么关系？也许有一些 Linux 约定？

Answer 1

问题可能出在这里:

@Override
public void writeString(String label, String value) {
  writeInt32(null, value.length());
  for (byte letter : value.getBytes()) {
      System.out.println((int)letter);
      writeInt8(null, letter);
  }
}

您正在以字符为单位写入长度，但随后继续从 getBytes() 写入字节。 getBytes() 使用字符串的平台编码，并且根据编码的不同，getBytes() 可以返回任何内容。

尝试明确指定编码，例如value.getBytes(Charset.forName("ISO-8859-1"));

编辑:还要确保您输出的字符串确实包含您认为它们包含的内容。