下面是我的代码替换DataInputStream来包装一个InputStream,但是除了读取大尾数类型的普通方法之外,还提供了额外的方法来读取小端数据类型.如果你愿意,随意使用它.
我有几点保留如下.注意不改变功能的方法(读取大尾数类型的函数).没有办法我可以实现DataInputStream作为基类,并使用它的方法,如read(),readInt(),readChar()等等？
我的班级层次似乎有点奇怪.这是否合适？
像readUTF()或readLine()这样的其他类型的其他类型需要一个小的endian版本吗？还是主观具体方案？
Java如何存储布尔类型？这是否也是主观的？
感谢您的满足我的好奇心:)
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,refBuffer.length);
}
@Override
public final void readFully(byte refBuffer[],int readLen) throws IOException {
dataInStream.readFully(refBuffer,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,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,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,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,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,2);
return ((byteBuffer[1] & 0xff) << 8 | (byteBuffer[0] & 0xff));
}
}
解决方法
readBoolean()读取一个字节.
readLine()读取单个字节并将其转换为char.
readUTF()读取修改的UTF-8(其代码单元大小为一个八位位组). UTF-8有no endianness.
这些方法没有任何关注.
关于设计,请考虑该类型是否需要InputStream,以及ByteBuffer是否有用.如果您没有使用像mark / reset和Closeable这样的功能,您可能不会公开新的类型：
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();
}
}
我注意到,流行的番石榴图书馆已经有LittleEndianDataInputStream.
