1 /* 2 * Copyright (C) 2010 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package android.util; 18 19 import android.annotation.UnsupportedAppUsage; 20 import java.io.FilterOutputStream; 21 import java.io.IOException; 22 import java.io.OutputStream; 23 24 /** 25 * An OutputStream that does Base64 encoding on the data written to 26 * it, writing the resulting data to another OutputStream. 27 */ 28 public class Base64OutputStream extends FilterOutputStream { 29 private final Base64.Coder coder; 30 private final int flags; 31 32 private byte[] buffer = null; 33 private int bpos = 0; 34 35 private static byte[] EMPTY = new byte[0]; 36 37 /** 38 * Performs Base64 encoding on the data written to the stream, 39 * writing the encoded data to another OutputStream. 40 * 41 * @param out the OutputStream to write the encoded data to 42 * @param flags bit flags for controlling the encoder; see the 43 * constants in {@link Base64} 44 */ Base64OutputStream(OutputStream out, int flags)45 public Base64OutputStream(OutputStream out, int flags) { 46 this(out, flags, true); 47 } 48 49 /** 50 * Performs Base64 encoding or decoding on the data written to the 51 * stream, writing the encoded/decoded data to another 52 * OutputStream. 53 * 54 * @param out the OutputStream to write the encoded data to 55 * @param flags bit flags for controlling the encoder; see the 56 * constants in {@link Base64} 57 * @param encode true to encode, false to decode 58 * 59 * @hide 60 */ 61 @UnsupportedAppUsage Base64OutputStream(OutputStream out, int flags, boolean encode)62 public Base64OutputStream(OutputStream out, int flags, boolean encode) { 63 super(out); 64 this.flags = flags; 65 if (encode) { 66 coder = new Base64.Encoder(flags, null); 67 } else { 68 coder = new Base64.Decoder(flags, null); 69 } 70 } 71 write(int b)72 public void write(int b) throws IOException { 73 // To avoid invoking the encoder/decoder routines for single 74 // bytes, we buffer up calls to write(int) in an internal 75 // byte array to transform them into writes of decently-sized 76 // arrays. 77 78 if (buffer == null) { 79 buffer = new byte[1024]; 80 } 81 if (bpos >= buffer.length) { 82 // internal buffer full; write it out. 83 internalWrite(buffer, 0, bpos, false); 84 bpos = 0; 85 } 86 buffer[bpos++] = (byte) b; 87 } 88 89 /** 90 * Flush any buffered data from calls to write(int). Needed 91 * before doing a write(byte[], int, int) or a close(). 92 */ flushBuffer()93 private void flushBuffer() throws IOException { 94 if (bpos > 0) { 95 internalWrite(buffer, 0, bpos, false); 96 bpos = 0; 97 } 98 } 99 write(byte[] b, int off, int len)100 public void write(byte[] b, int off, int len) throws IOException { 101 if (len <= 0) return; 102 flushBuffer(); 103 internalWrite(b, off, len, false); 104 } 105 close()106 public void close() throws IOException { 107 IOException thrown = null; 108 try { 109 flushBuffer(); 110 internalWrite(EMPTY, 0, 0, true); 111 } catch (IOException e) { 112 thrown = e; 113 } 114 115 try { 116 if ((flags & Base64.NO_CLOSE) == 0) { 117 out.close(); 118 } else { 119 out.flush(); 120 } 121 } catch (IOException e) { 122 if (thrown == null) { 123 thrown = e; 124 } else { 125 thrown.addSuppressed(e); 126 } 127 } 128 129 if (thrown != null) { 130 throw thrown; 131 } 132 } 133 134 /** 135 * Write the given bytes to the encoder/decoder. 136 * 137 * @param finish true if this is the last batch of input, to cause 138 * encoder/decoder state to be finalized. 139 */ internalWrite(byte[] b, int off, int len, boolean finish)140 private void internalWrite(byte[] b, int off, int len, boolean finish) throws IOException { 141 coder.output = embiggen(coder.output, coder.maxOutputSize(len)); 142 if (!coder.process(b, off, len, finish)) { 143 throw new Base64DataException("bad base-64"); 144 } 145 out.write(coder.output, 0, coder.op); 146 } 147 148 /** 149 * If b.length is at least len, return b. Otherwise return a new 150 * byte array of length len. 151 */ embiggen(byte[] b, int len)152 private byte[] embiggen(byte[] b, int len) { 153 if (b == null || b.length < len) { 154 return new byte[len]; 155 } else { 156 return b; 157 } 158 } 159 } 160