001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018 package org.apache.commons.codec.binary;
019
020 import java.io.FilterInputStream;
021 import java.io.IOException;
022 import java.io.InputStream;
023
024 /**
025 * Provides Base64 encoding and decoding in a streaming fashion (unlimited size). When encoding the default lineLength
026 * is 76 characters and the default lineEnding is CRLF, but these can be overridden by using the appropriate
027 * constructor.
028 * <p>
029 * The default behaviour of the Base64InputStream is to DECODE, whereas the default behaviour of the Base64OutputStream
030 * is to ENCODE, but this behaviour can be overridden by using a different constructor.
031 * </p>
032 * <p>
033 * This class implements section <cite>6.8. Base64 Content-Transfer-Encoding</cite> from RFC 2045 <cite>Multipurpose
034 * Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies</cite> by Freed and Borenstein.
035 * </p>
036 * <p>
037 * Since this class operates directly on byte streams, and not character streams, it is hard-coded to only encode/decode
038 * character encodings which are compatible with the lower 127 ASCII chart (ISO-8859-1, Windows-1252, UTF-8, etc).
039 * </p>
040 *
041 * @author Apache Software Foundation
042 * @version $Id: Base64InputStream.java 799805 2009-08-01 04:33:05Z ggregory $
043 * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>
044 * @since 1.4
045 */
046 public class Base64InputStream extends FilterInputStream {
047
048 private final boolean doEncode;
049
050 private final Base64 base64;
051
052 private final byte[] singleByte = new byte[1];
053
054 /**
055 * Creates a Base64InputStream such that all data read is Base64-decoded from the original provided InputStream.
056 *
057 * @param in
058 * InputStream to wrap.
059 */
060 public Base64InputStream(InputStream in) {
061 this(in, false);
062 }
063
064 /**
065 * Creates a Base64InputStream such that all data read is either Base64-encoded or Base64-decoded from the original
066 * provided InputStream.
067 *
068 * @param in
069 * InputStream to wrap.
070 * @param doEncode
071 * true if we should encode all data read from us, false if we should decode.
072 */
073 public Base64InputStream(InputStream in, boolean doEncode) {
074 super(in);
075 this.doEncode = doEncode;
076 this.base64 = new Base64();
077 }
078
079 /**
080 * Creates a Base64InputStream such that all data read is either Base64-encoded or Base64-decoded from the original
081 * provided InputStream.
082 *
083 * @param in
084 * InputStream to wrap.
085 * @param doEncode
086 * true if we should encode all data read from us, false if we should decode.
087 * @param lineLength
088 * If doEncode is true, each line of encoded data will contain lineLength characters (rounded down to
089 * nearest multiple of 4). If lineLength <=0, the encoded data is not divided into lines. If doEncode is
090 * false, lineLength is ignored.
091 * @param lineSeparator
092 * If doEncode is true, each line of encoded data will be terminated with this byte sequence (e.g. \r\n).
093 * If lineLength <= 0, the lineSeparator is not used. If doEncode is false lineSeparator is ignored.
094 */
095 public Base64InputStream(InputStream in, boolean doEncode, int lineLength, byte[] lineSeparator) {
096 super(in);
097 this.doEncode = doEncode;
098 this.base64 = new Base64(lineLength, lineSeparator);
099 }
100
101 /**
102 * Reads one <code>byte</code> from this input stream.
103 *
104 * @return the byte as an integer in the range 0 to 255. Returns -1 if EOF has been reached.
105 * @throws IOException
106 * if an I/O error occurs.
107 */
108 public int read() throws IOException {
109 int r = read(singleByte, 0, 1);
110 while (r == 0) {
111 r = read(singleByte, 0, 1);
112 }
113 if (r > 0) {
114 return singleByte[0] < 0 ? 256 + singleByte[0] : singleByte[0];
115 }
116 return -1;
117 }
118
119 /**
120 * Attempts to read <code>len</code> bytes into the specified <code>b</code> array starting at <code>offset</code>
121 * from this InputStream.
122 *
123 * @param b
124 * destination byte array
125 * @param offset
126 * where to start writing the bytes
127 * @param len
128 * maximum number of bytes to read
129 *
130 * @return number of bytes read
131 * @throws IOException
132 * if an I/O error occurs.
133 * @throws NullPointerException
134 * if the byte array parameter is null
135 * @throws IndexOutOfBoundsException
136 * if offset, len or buffer size are invalid
137 */
138 public int read(byte b[], int offset, int len) throws IOException {
139 if (b == null) {
140 throw new NullPointerException();
141 } else if (offset < 0 || len < 0) {
142 throw new IndexOutOfBoundsException();
143 } else if (offset > b.length || offset + len > b.length) {
144 throw new IndexOutOfBoundsException();
145 } else if (len == 0) {
146 return 0;
147 } else {
148 if (!base64.hasData()) {
149 byte[] buf = new byte[doEncode ? 4096 : 8192];
150 int c = in.read(buf);
151 // A little optimization to avoid System.arraycopy()
152 // when possible.
153 if (c > 0 && b.length == len) {
154 base64.setInitialBuffer(b, offset, len);
155 }
156 if (doEncode) {
157 base64.encode(buf, 0, c);
158 } else {
159 base64.decode(buf, 0, c);
160 }
161 }
162 return base64.readResults(b, offset, len);
163 }
164 }
165
166 /**
167 * {@inheritDoc}
168 *
169 * @return false
170 */
171 public boolean markSupported() {
172 return false; // not an easy job to support marks
173 }
174 }