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
017 package com.google.common.io;
018
019 import com.google.common.annotations.Beta;
020 import com.google.common.base.Preconditions;
021 import com.google.common.primitives.Longs;
022
023 import java.io.DataOutput;
024 import java.io.DataOutputStream;
025 import java.io.FilterOutputStream;
026 import java.io.IOException;
027 import 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 chrisn@google.com (Chris Nokleberg)
039 * @author kbottner@google.com (Keith Bottner)
040 * @since 8
041 */
042 @Beta
043 public 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 }