001 /* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, 013 * software distributed under the License is distributed on an 014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 * KIND, either express or implied. See the License for the 016 * specific language governing permissions and limitations 017 * under the License. 018 */ 019 020 package org.apache.geronimo.mail.util; 021 022 import java.io.IOException; 023 import java.io.OutputStream; 024 import java.io.FilterOutputStream; 025 026 /** 027 * An implementation of a FilterOutputStream that encodes the 028 * stream data in BASE64 encoding format. This version does the 029 * encoding "on the fly" rather than encoding a single block of 030 * data. Since this version is intended for use by the MimeUtilty class, 031 * it also handles line breaks in the encoded data. 032 * 033 * @version $Rev: 467553 $ $Date: 2006-10-25 06:01:51 +0200 (Mi, 25. Okt 2006) $ 034 */ 035 public class Base64EncoderStream extends FilterOutputStream { 036 037 // our Filtered stream writes everything out as byte data. This allows the CRLF sequence to 038 // be written with a single call. 039 protected static final byte[] CRLF = { '\r', '\n' }; 040 041 // our hex encoder utility class. 042 protected Base64Encoder encoder = new Base64Encoder(); 043 044 // our default for line breaks 045 protected static final int DEFAULT_LINEBREAK = 76; 046 047 // Data can only be written out in complete units of 3 bytes encoded as 4. Therefore, we need to buffer 048 // as many as 2 bytes to fill out an encoding unit. 049 050 // the buffered byte count 051 protected int bufferedBytes = 0; 052 053 // we'll encode this part once it is filled up. 054 protected byte[] buffer = new byte[3]; 055 056 057 // the size we process line breaks at. If this is Integer.MAX_VALUE, no line breaks are handled. 058 protected int lineBreak; 059 060 // the number of encoded characters we've written to the stream, which determines where we 061 // insert line breaks. 062 protected int outputCount; 063 064 /** 065 * Create a Base64 encoder stream that wraps a specifed stream 066 * using the default line break size. 067 * 068 * @param out The wrapped output stream. 069 */ 070 public Base64EncoderStream(OutputStream out) { 071 this(out, DEFAULT_LINEBREAK); 072 } 073 074 075 public Base64EncoderStream(OutputStream out, int lineBreak) { 076 super(out); 077 // lines are processed only in multiple of 4, so round this down. 078 this.lineBreak = (lineBreak / 4) * 4 ; 079 } 080 081 // in order for this to work, we need to override the 3 different signatures for write 082 083 public void write(int ch) throws IOException { 084 // store this in the buffer. 085 buffer[bufferedBytes++] = (byte)ch; 086 // if the buffer is filled, encode these bytes 087 if (bufferedBytes == 3) { 088 // check for room in the current line for this character 089 checkEOL(4); 090 // write these directly to the stream. 091 encoder.encode(buffer, 0, 3, out); 092 bufferedBytes = 0; 093 // and update the line length checkers 094 updateLineCount(4); 095 } 096 } 097 098 public void write(byte [] data) throws IOException { 099 write(data, 0, data.length); 100 } 101 102 public void write(byte [] data, int offset, int length) throws IOException { 103 // if we have something in the buffer, we need to write enough bytes out to flush 104 // those into the output stream AND continue on to finish off a line. Once we're done there 105 // we can write additional data out in complete blocks. 106 while ((bufferedBytes > 0 || outputCount > 0) && length > 0) { 107 write(data[offset++]); 108 length--; 109 } 110 111 if (length > 0) { 112 // no linebreaks requested? YES!!!!!, we can just dispose of the lot with one call. 113 if (lineBreak == Integer.MAX_VALUE) { 114 encoder.encode(data, offset, length, out); 115 } 116 else { 117 // calculate the size of a segment we can encode directly as a line. 118 int segmentSize = (lineBreak / 4) * 3; 119 120 // write this out a block at a time, with separators between. 121 while (length > segmentSize) { 122 // encode a segment 123 encoder.encode(data, offset, segmentSize, out); 124 // write an EOL marker 125 out.write(CRLF); 126 offset += segmentSize; 127 length -= segmentSize; 128 } 129 130 // any remainder we write out a byte at a time to manage the groupings and 131 // the line count appropriately. 132 if (length > 0) { 133 while (length > 0) { 134 write(data[offset++]); 135 length--; 136 } 137 } 138 } 139 } 140 } 141 142 public void close() throws IOException { 143 flush(); 144 out.close(); 145 } 146 147 public void flush() throws IOException { 148 if (bufferedBytes > 0) { 149 encoder.encode(buffer, 0, bufferedBytes, out); 150 bufferedBytes = 0; 151 } 152 } 153 154 155 /** 156 * Check for whether we're about the reach the end of our 157 * line limit for an update that's about to occur. If we will 158 * overflow, then a line break is inserted. 159 * 160 * @param required The space required for this pending write. 161 * 162 * @exception IOException 163 */ 164 private void checkEOL(int required) throws IOException { 165 if (lineBreak != Integer.MAX_VALUE) { 166 // if this write would exceed the line maximum, add a linebreak to the stream. 167 if (outputCount + required > lineBreak) { 168 out.write(CRLF); 169 outputCount = 0; 170 } 171 } 172 } 173 174 /** 175 * Update the counter of characters on the current working line. 176 * This is conditional if we're not working with a line limit. 177 * 178 * @param added The number of characters just added. 179 */ 180 private void updateLineCount(int added) { 181 if (lineBreak != Integer.MAX_VALUE) { 182 outputCount += added; 183 } 184 } 185 } 186