001/*
002 * Copyright (C) 2007 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package com.google.common.io;
018
019import com.google.common.annotations.Beta;
020import com.google.common.base.Preconditions;
021import com.google.common.primitives.Longs;
022
023import java.io.DataOutput;
024import java.io.DataOutputStream;
025import java.io.FilterOutputStream;
026import java.io.IOException;
027import java.io.OutputStream;
028
029/**
030 * An implementation of {@link DataOutput} that uses little-endian byte ordering
031 * for writing {@code char}, {@code short}, {@code int}, {@code float}, {@code
032 * double}, and {@code long} values.
033 * <p>
034 * <b>Note:</b> This class intentionally violates the specification of its
035 * supertype {@code DataOutput}, which explicitly requires big-endian byte
036 * order.
037 *
038 * @author Chris Nokleberg
039 * @author Keith Bottner
040 * @since 8.0
041 */
042@Beta
043public class LittleEndianDataOutputStream extends FilterOutputStream
044    implements DataOutput {
045
046  /**
047   * Creates a {@code LittleEndianDataOutputStream} that wraps the given stream.
048   *
049   * @param out the stream to delegate to
050   */
051  public LittleEndianDataOutputStream(OutputStream out) {
052    super(new DataOutputStream(Preconditions.checkNotNull(out)));
053  }
054
055  @Override public void write(byte[] b, int off, int len) throws IOException {
056    // Override slow FilterOutputStream impl
057    out.write(b, off, len);
058  }
059
060  @Override public void writeBoolean(boolean v) throws IOException {
061    ((DataOutputStream) out).writeBoolean(v);
062  }
063
064  @Override public void writeByte(int v) throws IOException {
065    ((DataOutputStream) out).writeByte(v);
066  }
067
068  /**
069   * @deprecated The semantics of {@code writeBytes(String s)} are considered
070   *             dangerous. Please use {@link #writeUTF(String s)},
071   *             {@link #writeChars(String s)} or another write method instead.
072   */
073  @Deprecated
074  @Override public void writeBytes(String s) throws IOException {
075    ((DataOutputStream) out).writeBytes(s);
076  }
077
078  /**
079   * Writes a char as specified by {@link DataOutputStream#writeChar(int)},
080   * except using little-endian byte order.
081   *
082   * @throws IOException if an I/O error occurs
083   */
084  @Override public void writeChar(int v) throws IOException {
085    writeShort(v);
086  }
087
088  /**
089   * Writes a {@code String} as specified by
090   * {@link DataOutputStream#writeChars(String)}, except each character is
091   * written using little-endian byte order.
092   *
093   * @throws IOException if an I/O error occurs
094   */
095  @Override public void writeChars(String s) throws IOException {
096    for (int i = 0; i < s.length(); i++) {
097      writeChar(s.charAt(i));
098    }
099  }
100
101  /**
102   * Writes a {@code double} as specified by
103   * {@link DataOutputStream#writeDouble(double)}, except using little-endian
104   * byte order.
105   *
106   * @throws IOException if an I/O error occurs
107   */
108  @Override public void writeDouble(double v) throws IOException {
109    writeLong(Double.doubleToLongBits(v));
110  }
111
112  /**
113   * Writes a {@code float} as specified by
114   * {@link DataOutputStream#writeFloat(float)}, except using little-endian byte
115   * order.
116   *
117   * @throws IOException if an I/O error occurs
118   */
119  @Override public void writeFloat(float v) throws IOException {
120    writeInt(Float.floatToIntBits(v));
121  }
122
123  /**
124   * Writes an {@code int} as specified by
125   * {@link DataOutputStream#writeInt(int)}, except using little-endian byte
126   * order.
127   *
128   * @throws IOException if an I/O error occurs
129   */
130  @Override public void writeInt(int v) throws IOException {
131    out.write(0xFF & v);
132    out.write(0xFF & (v >> 8));
133    out.write(0xFF & (v >> 16));
134    out.write(0xFF & (v >> 24));
135  }
136
137  /**
138   * Writes a {@code long} as specified by
139   * {@link DataOutputStream#writeLong(long)}, except using little-endian byte
140   * order.
141   *
142   * @throws IOException if an I/O error occurs
143   */
144  @Override public void writeLong(long v) throws IOException {
145    byte[] bytes = Longs.toByteArray(Long.reverseBytes(v));
146    write(bytes, 0, bytes.length);
147  }
148
149  /**
150   * Writes a {@code short} as specified by
151   * {@link DataOutputStream#writeShort(int)}, except using little-endian byte
152   * order.
153   *
154   * @throws IOException if an I/O error occurs
155   */
156  @Override public void writeShort(int v) throws IOException {
157    out.write(0xFF & v);
158    out.write(0xFF & (v >> 8));
159  }
160
161  @Override public void writeUTF(String str) throws IOException {
162    ((DataOutputStream) out).writeUTF(str);
163  }
164}