1 /* 2 * Copyright (C) 2008 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 com.android.email; 18 19 import java.io.IOException; 20 import java.io.InputStream; 21 22 /** 23 * A filtering InputStream that allows single byte "peeks" without consuming the byte. The 24 * client of this stream can call peek() to see the next available byte in the stream 25 * and a subsequent read will still return the peeked byte. 26 */ 27 public class PeekableInputStream extends InputStream { 28 private final InputStream mIn; 29 private boolean mPeeked; 30 private int mPeekedByte; 31 PeekableInputStream(InputStream in)32 public PeekableInputStream(InputStream in) { 33 this.mIn = in; 34 } 35 36 @Override read()37 public int read() throws IOException { 38 if (!mPeeked) { 39 return mIn.read(); 40 } else { 41 mPeeked = false; 42 return mPeekedByte; 43 } 44 } 45 peek()46 public int peek() throws IOException { 47 if (!mPeeked) { 48 mPeekedByte = read(); 49 mPeeked = true; 50 } 51 return mPeekedByte; 52 } 53 54 @Override read(byte[] b, int offset, int length)55 public int read(byte[] b, int offset, int length) throws IOException { 56 if (!mPeeked) { 57 return mIn.read(b, offset, length); 58 } else { 59 b[0] = (byte)mPeekedByte; 60 mPeeked = false; 61 int r = mIn.read(b, offset + 1, length - 1); 62 if (r == -1) { 63 return 1; 64 } else { 65 return r + 1; 66 } 67 } 68 } 69 70 @Override read(byte[] b)71 public int read(byte[] b) throws IOException { 72 return read(b, 0, b.length); 73 } 74 75 @Override toString()76 public String toString() { 77 return String.format("PeekableInputStream(in=%s, peeked=%b, peekedByte=%d)", 78 mIn.toString(), mPeeked, mPeekedByte); 79 } 80 } 81