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, software 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018package org.apache.hadoop.hbase.io; 019 020import java.io.InputStream; 021import java.nio.ByteBuffer; 022import org.apache.hadoop.hbase.util.ByteBufferUtils; 023import org.apache.yetus.audience.InterfaceAudience; 024 025/** 026 * Not thread safe! 027 * <p> 028 * Please note that the reads will cause position movement on wrapped ByteBuffer. 029 */ 030@InterfaceAudience.Private 031public class ByteBufferInputStream extends InputStream { 032 033 private ByteBuffer buf; 034 035 public ByteBufferInputStream(ByteBuffer buf) { 036 this.buf = buf; 037 } 038 039 /** 040 * Reads the next byte of data from this input stream. The value byte is returned as an 041 * <code>int</code> in the range <code>0</code> to <code>255</code>. If no byte is available 042 * because the end of the stream has been reached, the value <code>-1</code> is returned. 043 * @return the next byte of data, or <code>-1</code> if the end of the stream has been reached. 044 */ 045 @Override 046 public int read() { 047 if (this.buf.hasRemaining()) { 048 return (this.buf.get() & 0xff); 049 } 050 return -1; 051 } 052 053 /** 054 * Reads up to next <code>len</code> bytes of data from buffer into passed array(starting from 055 * given offset). 056 * @param b the array into which the data is read. 057 * @param off the start offset in the destination array <code>b</code> 058 * @param len the maximum number of bytes to read. 059 * @return the total number of bytes actually read into the buffer, or <code>-1</code> if not even 060 * 1 byte can be read because the end of the stream has been reached. 061 */ 062 @Override 063 public int read(byte[] b, int off, int len) { 064 int avail = available(); 065 if (avail <= 0) { 066 return -1; 067 } 068 069 if (len > avail) { 070 len = avail; 071 } 072 if (len <= 0) { 073 return 0; 074 } 075 076 ByteBufferUtils.copyFromBufferToArray(b, this.buf, this.buf.position(), off, len); 077 this.buf.position(this.buf.position() + len); // we should advance the buffer position 078 return len; 079 } 080 081 /** 082 * Skips <code>n</code> bytes of input from this input stream. Fewer bytes might be skipped if the 083 * end of the input stream is reached. The actual number <code>k</code> of bytes to be skipped is 084 * equal to the smaller of <code>n</code> and remaining bytes in the stream. 085 * @param n the number of bytes to be skipped. 086 * @return the actual number of bytes skipped. 087 */ 088 @Override 089 public long skip(long n) { 090 long k = Math.min(n, available()); 091 if (k < 0) { 092 k = 0; 093 } 094 this.buf.position((int) (this.buf.position() + k)); 095 return k; 096 } 097 098 /** 099 * @return the number of remaining bytes that can be read (or skipped over) from this input 100 * stream. 101 */ 102 @Override 103 public int available() { 104 return this.buf.remaining(); 105 } 106}