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 java.io.FilterInputStream; 20 import java.io.IOException; 21 import java.io.InputStream; 22 23 /** 24 * An InputStream that does Base64 decoding on the data read through 25 * it. 26 */ 27 public class Base64InputStream extends FilterInputStream { 28 private final Base64.Coder coder; 29 30 private static byte[] EMPTY = new byte[0]; 31 32 private static final int BUFFER_SIZE = 2048; 33 private boolean eof; 34 private byte[] inputBuffer; 35 private int outputStart; 36 private int outputEnd; 37 38 /** 39 * An InputStream that performs Base64 decoding on the data read 40 * from the wrapped stream. 41 * 42 * @param in the InputStream to read the source data from 43 * @param flags bit flags for controlling the decoder; see the 44 * constants in {@link Base64} 45 */ Base64InputStream(InputStream in, int flags)46 public Base64InputStream(InputStream in, int flags) { 47 this(in, flags, false); 48 } 49 50 /** 51 * Performs Base64 encoding or decoding on the data read from the 52 * wrapped InputStream. 53 * 54 * @param in the InputStream to read the source data from 55 * @param flags bit flags for controlling the decoder; see the 56 * constants in {@link Base64} 57 * @param encode true to encode, false to decode 58 * 59 * @hide 60 */ Base64InputStream(InputStream in, int flags, boolean encode)61 public Base64InputStream(InputStream in, int flags, boolean encode) { 62 super(in); 63 eof = false; 64 inputBuffer = new byte[BUFFER_SIZE]; 65 if (encode) { 66 coder = new Base64.Encoder(flags, null); 67 } else { 68 coder = new Base64.Decoder(flags, null); 69 } 70 coder.output = new byte[coder.maxOutputSize(BUFFER_SIZE)]; 71 outputStart = 0; 72 outputEnd = 0; 73 } 74 markSupported()75 public boolean markSupported() { 76 return false; 77 } 78 mark(int readlimit)79 public void mark(int readlimit) { 80 throw new UnsupportedOperationException(); 81 } 82 reset()83 public void reset() { 84 throw new UnsupportedOperationException(); 85 } 86 close()87 public void close() throws IOException { 88 in.close(); 89 inputBuffer = null; 90 } 91 available()92 public int available() { 93 return outputEnd - outputStart; 94 } 95 skip(long n)96 public long skip(long n) throws IOException { 97 if (outputStart >= outputEnd) { 98 refill(); 99 } 100 if (outputStart >= outputEnd) { 101 return 0; 102 } 103 long bytes = Math.min(n, outputEnd-outputStart); 104 outputStart += bytes; 105 return bytes; 106 } 107 read()108 public int read() throws IOException { 109 if (outputStart >= outputEnd) { 110 refill(); 111 } 112 if (outputStart >= outputEnd) { 113 return -1; 114 } else { 115 return coder.output[outputStart++] & 0xff; 116 } 117 } 118 read(byte[] b, int off, int len)119 public int read(byte[] b, int off, int len) throws IOException { 120 if (outputStart >= outputEnd) { 121 refill(); 122 } 123 if (outputStart >= outputEnd) { 124 return -1; 125 } 126 int bytes = Math.min(len, outputEnd-outputStart); 127 System.arraycopy(coder.output, outputStart, b, off, bytes); 128 outputStart += bytes; 129 return bytes; 130 } 131 132 /** 133 * Read data from the input stream into inputBuffer, then 134 * decode/encode it into the empty coder.output, and reset the 135 * outputStart and outputEnd pointers. 136 */ refill()137 private void refill() throws IOException { 138 if (eof) return; 139 int bytesRead = in.read(inputBuffer); 140 boolean success; 141 if (bytesRead == -1) { 142 eof = true; 143 success = coder.process(EMPTY, 0, 0, true); 144 } else { 145 success = coder.process(inputBuffer, 0, bytesRead, false); 146 } 147 if (!success) { 148 throw new Base64DataException("bad base-64"); 149 } 150 outputEnd = coder.op; 151 outputStart = 0; 152 } 153 } 154