Java: el reemplazo de DataInputStream endianness

Question

A continuación se muestra el código que sustituye a la DataInputStream para envolver un InputStream, pero proporciona métodos adicionales a leer pequeños tipos de datos endian, además de los métodos normales que leen grandes tipos endian. Siéntase libre de usarlo si lo desea.

Tengo algunas reservas de la siguiente manera. Observe los métodos que no cambian la funcionalidad (las funciones que leen los tipos de Big Endian). No hay forma de que pueda implementar DataInputStream como clase base y usar sus métodos, como read(), readInt(), readChar(), etc.

Mi jerarquía de clases parece un poco extraña aquí. ¿Es esto apropiado?

¿Alguno de estos otros tipos como readUTF() o readLine() necesita un poco de la versión endian? ¿O es eso subjetivo para programas específicos?

¿Cómo funciona Java almacenar tipos booleanos? ¿Es eso subjetivo para endianness también?

Gracias para satisfacer mis curiosidades :)

import java.io.*; 

/** 
* Replacement for a DataInputStream that provides both little and big endian reading capabilities for convenience without need to implement a ByteBuffer 
* @author Bill (unspecified.specification@gmail.com) 
*/ 
public class EndianInputStream extends InputStream implements DataInput { 
    private DataInputStream dataInStream; 
    private InputStream inStream; 
    private byte byteBuffer[]; 

    /** 
    * Constructor to wrap InputStream for little and big endian data 
    * @param refInStream Inputstream to wrap 
    */ 
    public EndianInputStream(InputStream refInStream) { 
     inStream = refInStream; 
     dataInStream = new DataInputStream(inStream); 
     byteBuffer = new byte[8]; // Largest data type is 64-bits (8 bytes) 
    } 

    @Override 
    public int available() throws IOException { 
     return dataInStream.available(); 
    } 

    @Override 
    public final int read(byte refBuffer[], int offset, int readLen) throws IOException { 
     return inStream.read(refBuffer, offset, readLen); 
    } 

    @Override 
    public int read() throws IOException { 
     return inStream.read(); 
    } 

    @Override 
    public final int readUnsignedByte() throws IOException { 
     return dataInStream.readUnsignedByte(); 
    } 

    @Deprecated 
    @Override 
    public final String readLine() throws IOException { 
     return dataInStream.readLine(); 
    } 

    @Override 
    public final String readUTF() throws IOException { 
     return dataInStream.readUTF(); 
    } 

    @Override 
    public final void close() throws IOException { 
     dataInStream.close(); 
    } 

    @Override 
    public final void readFully(byte refBuffer[]) throws IOException { 
     dataInStream.readFully(refBuffer, 0, refBuffer.length); 
    } 

    @Override 
    public final void readFully(byte refBuffer[], int offset, int readLen) throws IOException { 
     dataInStream.readFully(refBuffer, offset, readLen); 
    } 

    @Override 
    public final int skipBytes(int n) throws IOException { 
     return dataInStream.skipBytes(n); 
    } 

    @Override 
    public final boolean readBoolean() throws IOException { 
     return dataInStream.readBoolean(); 
    } 

    @Override 
    public final byte readByte() throws IOException { 
     return dataInStream.readByte(); 
    } 

    @Override 
    public final float readFloat() throws IOException { 
     return Float.intBitsToFloat(readInt()); 
    } 

    @Override 
    public final double readDouble() throws IOException { 
     return Double.longBitsToDouble(readLong()); 
    } 

    @Override 
    public final short readShort() throws IOException { 
     return dataInStream.readShort(); 
    } 

    @Override 
    public final int readUnsignedShort() throws IOException { 
     return dataInStream.readUnsignedShort(); 
    } 

    @Override 
    public final long readLong() throws IOException { 
     return dataInStream.readLong(); 
    } 

    @Override 
    public final char readChar() throws IOException { 
     return dataInStream.readChar(); 
    } 

    @Override 
    public final int readInt() throws IOException { 
     return dataInStream.readInt(); 
    } 

    /** 
    * Reads floating point type stored in little endian (see readFloat() for big endian) 
    * @return float value translated from little endian 
    * @throws IOException if an IO error occurs 
    */ 
    public final float readLittleFloat() throws IOException { 
     return Float.intBitsToFloat(readLittleInt()); 
    }  

    /** 
    * Reads double precision floating point type stored in little endian (see readDouble() for big endian) 
    * @return double precision float value translated from little endian 
    * @throws IOException if an IO error occurs 
    */  
    public final double readLittleDouble() throws IOException { 
     return Double.longBitsToDouble(readLittleLong()); 
    } 

    /** 
    * Reads short type stored in little endian (see readShort() for big endian) 
    * @return short value translated from little endian 
    * @throws IOException if an IO error occurs 
    */  
    public final short readLittleShort() throws IOException { 
    dataInStream.readFully(byteBuffer, 0, 2); 
    return (short)((byteBuffer[1] & 0xff) << 8 | (byteBuffer[0] & 0xff)); 
    } 

    /** 
    * Reads char (16-bits) type stored in little endian (see readChar() for big endian) 
    * @return char value translated from little endian 
    * @throws IOException if an IO error occurs 
    */  
    public final char readLittleChar() throws IOException { 
     dataInStream.readFully(byteBuffer, 0, 2); 
     return (char)((byteBuffer[1] & 0xff) << 8 | (byteBuffer[0] & 0xff)); 
    }  

    /** 
    * Reads integer type stored in little endian (see readInt() for big endian) 
    * @return integer value translated from little endian 
    * @throws IOException if an IO error occurs 
    */   
    public final int readLittleInt() throws IOException { 
     dataInStream.readFully(byteBuffer, 0, 4); 
     return (byteBuffer[3]) << 24 | (byteBuffer[2] & 0xff) << 16 | 
      (byteBuffer[1] & 0xff) << 8 | (byteBuffer[0] & 0xff); 
    } 

    /** 
    * Reads long type stored in little endian (see readLong() for big endian) 
    * @return long value translated from little endian 
    * @throws IOException if an IO error occurs 
    */   
    public final long readLittleLong() throws IOException { 
     dataInStream.readFully(byteBuffer, 0, 8); 
     return (long)(byteBuffer[7]) << 56 | (long)(byteBuffer[6]&0xff) << 48 | 
      (long)(byteBuffer[5] & 0xff) << 40 | (long)(byteBuffer[4] & 0xff) << 32 | 
      (long)(byteBuffer[3] & 0xff) << 24 | (long)(byteBuffer[2] & 0xff) << 16 | 
      (long)(byteBuffer[1] & 0xff) << 8 | (long)(byteBuffer[0] & 0xff); 
    } 

    /** 
    * Reads unsigned short type stored in little endian (see readUnsignedShort() for big endian) 
    * @return integer value representing unsigned short value translated from little endian 
    * @throws IOException if an IO error occurs 
    */   
    public final int readLittleUnsignedShort() throws IOException { 
     dataInStream.readFully(byteBuffer, 0, 2); 
     return ((byteBuffer[1] & 0xff) << 8 | (byteBuffer[0] & 0xff)); 
    } 
} 

Answer 1

readBoolean() lee un solo byte. readLine() lee bytes individuales y convierte cada uno a char.

readUTF() lecturas modificada UTF-8 (que tiene un tamaño de unidad de código de un octeto). UTF-8 tiene no endianness.

No hay problemas de endianness con estos métodos.

En cuanto al diseño, considere si el tipo debe ser un InputStream y si el ByteBuffer puede ser útil. Si no se está usando características como marca/reset y Closeable es posible que no exponga el nuevo tipo:

public class Bytes { 
    public static DataInput littleEndian(final DataInput decorated) { 
    class LittleInput implements DataInput { 
     private ByteBuffer buffer = ByteBuffer.allocate(8); 

     public int readInt() throws IOException { 
     buffer.clear(); 
     buffer.order(ByteOrder.BIG_ENDIAN) 
      .putInt(decorated.readInt()) 
      .flip(); 
     return buffer.order(ByteOrder.LITTLE_ENDIAN) 
      .getInt(); 
     } 

     //TODO: other methods  
    } 

    return new LittleInput(); 
    } 

} 

observo que la biblioteca de guayaba populares ya tiene LittleEndianDataInputStream.