main.java.com.mindprod.ledatastream.LittleEndianDataOutputStream Maven / Gradle / Ivy
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/**
* Description:
* LittleEndianDataOutputStream.java Create on 2014-5-14
*
* @author shaowenzhang
* @version 1.0
* Copyright (c) 2014 Tecent WXG AndroidTeam. All Rights Reserved.
*/
package com.mindprod.ledatastream;
/**
* Copyright (C) 2007 The Guava Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.io.DataOutput;
import java.io.DataOutputStream;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;
/***
* An implementation of {@link DataOutput} that uses little-endian byte ordering
* for writing {@code char}, {@code short}, {@code int}, {@code float}, {@code
* double}, and {@code long} values.
*
* Note: This class intentionally violates the specification of its
* supertype {@code DataOutput}, which explicitly requires big-endian byte
* order.
*
* @author Chris Nokleberg
* @author Keith Bottner
* @since 8.0
*/
public class LittleEndianDataOutputStream extends FilterOutputStream implements DataOutput {
/***
* Creates a {@code LittleEndianDataOutputStream} that wraps the given stream.
*
* @param out the stream to delegate to
*/
public LittleEndianDataOutputStream(OutputStream out) {
super(new DataOutputStream(out));
}
/***
* Returns a big-endian representation of {@code value} in an 8-element byte
* array; equivalent to {@code ByteBuffer.allocate(8).putLong(value).array()}.
* For example, the input value {@code 0x1213141516171819L} would yield the
* byte array {@code {0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19}}.
* @param value long
* @return byte array
*/
public static byte[] toByteArray(long value) {
// Note that this code needs to stay compatible with GWT, which has known
// bugs when narrowing byte casts of long values occur.
byte[] result = new byte[8];
for (int i = 7; i >= 0; i--) {
result[i] = (byte) (value & 0xffL);
value >>= 8;
}
return result;
}
@Override
public void write(byte[] b, int off, int len) throws IOException {
// Override slow FilterOutputStream impl
out.write(b, off, len);
}
@Override
public void writeBoolean(boolean v) throws IOException {
((DataOutputStream) out).writeBoolean(v);
}
@Override
public void writeByte(int v) throws IOException {
((DataOutputStream) out).writeByte(v);
}
/***
* @deprecated The semantics of {@code writeBytes(String s)} are considered
* dangerous. Please use {@link #writeUTF(String s)},
* {@link #writeChars(String s)} or another write method instead.
*/
@Deprecated
@Override
public void writeBytes(String s) throws IOException {
((DataOutputStream) out).writeBytes(s);
}
/***
* Writes a char as specified by {@link DataOutputStream#writeChar(int)},
* except using little-endian byte order.
*
* @throws IOException if an I/O error occurs
*/
@Override
public void writeChar(int v) throws IOException {
writeShort(v);
}
/***
* Writes a {@code String} as specified by
* {@link DataOutputStream#writeChars(String)}, except each character is
* written using little-endian byte order.
*
* @throws IOException if an I/O error occurs
*/
@Override
public void writeChars(String s) throws IOException {
for (int i = 0; i < s.length(); i++) {
writeChar(s.charAt(i));
}
}
/***
* Writes a {@code double} as specified by
* {@link DataOutputStream#writeDouble(double)}, except using little-endian
* byte order.
*
* @throws IOException if an I/O error occurs
*/
@Override
public void writeDouble(double v) throws IOException {
writeLong(Double.doubleToLongBits(v));
}
/***
* Writes a {@code float} as specified by
* {@link DataOutputStream#writeFloat(float)}, except using little-endian byte
* order.
*
* @throws IOException if an I/O error occurs
*/
@Override
public void writeFloat(float v) throws IOException {
writeInt(Float.floatToIntBits(v));
}
/***
* Writes an {@code int} as specified by
* {@link DataOutputStream#writeInt(int)}, except using little-endian byte
* order.
*
* @throws IOException if an I/O error occurs
*/
@Override
public void writeInt(int v) throws IOException {
out.write(0xFF & v);
out.write(0xFF & (v >> 8));
out.write(0xFF & (v >> 16));
out.write(0xFF & (v >> 24));
}
/***
* Writes a {@code long} as specified by
* {@link DataOutputStream#writeLong(long)}, except using little-endian byte
* order.
*
* @throws IOException if an I/O error occurs
*/
@Override
public void writeLong(long v) throws IOException {
byte[] bytes = toByteArray(Long.reverseBytes(v));
write(bytes, 0, bytes.length);
}
/***
* Writes a {@code short} as specified by
* {@link DataOutputStream#writeShort(int)}, except using little-endian byte
* order.
*
* @throws IOException if an I/O error occurs
*/
@Override
public void writeShort(int v) throws IOException {
out.write(0xFF & v);
out.write(0xFF & (v >> 8));
}
@Override
public void writeUTF(String str) throws IOException {
((DataOutputStream) out).writeUTF(str);
}
}