在java中将EBCDIC转换为ASCII [英] Converting EBCDIC to ASCII in java

问题描述

所以我应该使用Java将EBCDIC文件转换为ASCII。到目前为止，我有这段代码：

so I am supposed to convert an EBCDIC file to ASCII by using Java. So far I have this code:

public class Migration {
InputStreamReader reader;
StringBuilder builder;

public Migration(){
    try {
        reader = new InputStreamReader(new FileInputStream("C:\\TI3\\Legacy Systemen\\Week 3\\Oefening 3\\inputfile.dat"),
               java.nio.charset.Charset.forName("ibm500") );
    } catch(FileNotFoundException e){
        e.printStackTrace();
    }
    builder = new StringBuilder();
}

public void read() throws IOException {
    int theInt;
    while((theInt = reader.read()) != -1){
        char theChar = (char) theInt;
        builder.append(theChar);

    }

    reader.close();
}

@Override
public String toString(){
    return builder.toString();
    }
}

文件说明如下：

 02 KDGEX.
      05 B1-LENGTH PIC S9(04) USAGE IS COMP.
      05 B1-CODE PIC S9(04) USAGE IS COMP.
      05 B1-NUMBER PIC X(08).
      05 B1-PPR-NAME PIC X(06).
      05 B1-PPR-FED PIC 9(03).
      05 B1-PPR-RNR PIC S9(08) USAGE IS COMP.
      05 B1-DATA.
        10 B1-VBOND PIC 9(02).
        10 B1-KONST.
          20 B1-AFDEL PIC 9(03).
          20 B1-KASSIER PIC 9(03).
          20 B1-DATZIT-DM PIC 9(04).
        10 B1-BETWYZ PIC X(01).
        10 B1-RNR PIC X(13).
        10 B1-BETKOD PIC 9(02).
        10 B1-VOLGNR-INF PIC 9(02).
        10 B1-QUAL-PREST PIC 9(03).
        10 B1-REKNUM PIC 9(12).
        10 B1-REKNR REDEFINES B1-REKNUM.
          20 B1-REKNR-PART1 PIC 9(03).
          20 B1-REKNR-PART2 PIC 9(07).
          20 B1-REKNR-PART3 PIC 9(02).
        10 B1-VOLGNR-M30 PIC 9(03).
        10 B1-OMSCHR.
          15 B1-OMSCHR1 PIC X(14).
          15 B1-OMSCHR2 PIC X(14).
        10 B1-OMSCHR-INF REDEFINES B1-OMSCHR.
          15 B1-AANT-PREST PIC 9(02).
          15 B1-VERSTR PIC 9(01).
          15 B1-LASTDATE PIC 9(06).
          15 B1-HONOR PIC 9(06).
          15 B1-RIJKN PIC X(13).
        10 FILLER--1 PIC 9(02).
        10 B1-INFOREK PIC 9(01).
        10 B1-BEDRAG-EUR PIC 9(08).
        10 B1-BEDRAG-DV PIC X(01).
        10 B1-BEDRAG-RMG-DV REDEFINES B1-BEDRAG-DV PIC X(01).
      05 FILLER PIC X(5).

我们可以忽略每一行的前2个字节。问题是由于读者没有正确地转换它们，因此存在USAGE IS COMP的字节，我认为我应该将它们读作字节或其他东西，尽管我不知道如何。

We can ignore the first 2 bytes on every line. The problem is the bytes where there's a USAGE IS COMP since the reader is not converting them properly, I think I am supposed to read these as bytes or something, though I have no idea how.

推荐答案

如果我正确解释这种格式，你就会得到一个带有固定长度记录的二进制文件格式。其中一些记录不是字符数据（COBOL计算字段？）

If I am interpreting this format correctly you have a binary file format with fixed-length records. Some of these records are not character data (COBOL computational fields?)

因此，您必须使用更低级别的方法读取记录，每个字段处理各个字段记录：

So, you will have to read the records using a more low-level approach processing individual fields of each record:

import java.io.*;

public class Record {
  private byte[] kdgex = new byte[2]; // COMP
  private byte[] b1code = new byte[2]; // COMP
  private byte[] b1number = new byte[8]; // DISPLAY
  // other fields

  public void read(DataInput data) throws IOException {
    data.readFully(kdgex);
    data.readFully(b1code);
    data.readFully(b1number);
    // other fields
  }

  public void write(DataOutput out) throws IOException {
    out.write(kdgex);
    out.write(b1code);
    out.write(b1number);
    // other fields
  }
}

我在这里我为记录的前三个字段使用了字节数组，但您可以在适当的地方使用其他更合适的类型（如 short ，第一个字段 readShort 。）注意：我的字段宽度的解释可能是错误的;这只是一个例子。

Here I've used byte arrays for the first three fields of the record but you could use other more suitable types where appropriate (like a short for the first field with readShort.) Note: my interpretation of the field widths is likely wrong; it is just an example.

DataInputStream 通常用作 DataInput 实现。

由于源代码和目标编码中的所有字符都使用每个代码点一个八位字节您应该能够使用如下方法对字符数据字段进行转码：

Since all characters in the source and target encodings use a one-octet-per code point you should be able to transcode the character data fields using a method like this:

public static byte[] transcodeField(byte[] source, Charset from, Charset to) {
  byte[] result = new String(source, from).getBytes(to);
  if (result.length != source.length) {
    throw new AssertionError(result.length + "!=" + source.length);
  }
  return result;
}

我建议用COBOL标记你的问题（假设这是来源）这种格式）以便其他人可以对数据源的格式有更多权限。

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