com.feilong.lib.compress.utils.IOUtils Maven / Gradle / Ivy
Show all versions of feilong Show documentation
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package com.feilong.lib.compress.utils;
import java.io.ByteArrayOutputStream;
import java.io.Closeable;
import java.io.EOFException;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.ReadableByteChannel;
/**
* Utility functions
*
* @Immutable (has mutable data but it is write-only)
*/
public final class IOUtils{
private static final int COPY_BUF_SIZE = 8024;
private static final int SKIP_BUF_SIZE = 4096;
// This buffer does not need to be synchronised because it is write only; the contents are ignored
// Does not affect Immutability
private static final byte[] SKIP_BUF = new byte[SKIP_BUF_SIZE];
/** Private constructor to prevent instantiation of this utility class. */
private IOUtils(){
}
/**
* Copies the content of a InputStream into an OutputStream.
* Uses a default buffer size of 8024 bytes.
*
* @param input
* the InputStream to copy
* @param output
* the target Stream
* @return the number of bytes copied
* @throws IOException
* if an error occurs
*/
public static long copy(final InputStream input,final OutputStream output) throws IOException{
return copy(input, output, COPY_BUF_SIZE);
}
/**
* Copies the content of a InputStream into an OutputStream
*
* @param input
* the InputStream to copy
* @param output
* the target Stream
* @param buffersize
* the buffer size to use, must be bigger than 0
* @return the number of bytes copied
* @throws IOException
* if an error occurs
* @throws IllegalArgumentException
* if buffersize is smaller than or equal to 0
*/
public static long copy(final InputStream input,final OutputStream output,final int buffersize) throws IOException{
if (buffersize < 1){
throw new IllegalArgumentException("buffersize must be bigger than 0");
}
final byte[] buffer = new byte[buffersize];
int n = 0;
long count = 0;
while (-1 != (n = input.read(buffer))){
output.write(buffer, 0, n);
count += n;
}
return count;
}
/**
* Skips the given number of bytes by repeatedly invoking skip on
* the given input stream if necessary.
*
*
* In a case where the stream's skip() method returns 0 before
* the requested number of bytes has been skip this implementation
* will fall back to using the read() method.
*
*
*
* This method will only skip less than the requested number of
* bytes if the end of the input stream has been reached.
*
*
* @param input
* stream to skip bytes in
* @param numToSkip
* the number of bytes to skip
* @return the number of bytes actually skipped
* @throws IOException
* on error
*/
public static long skip(final InputStream input,long numToSkip) throws IOException{
final long available = numToSkip;
while (numToSkip > 0){
final long skipped = input.skip(numToSkip);
if (skipped == 0){
break;
}
numToSkip -= skipped;
}
while (numToSkip > 0){
final int read = readFully(input, SKIP_BUF, 0, (int) Math.min(numToSkip, SKIP_BUF_SIZE));
if (read < 1){
break;
}
numToSkip -= read;
}
return available - numToSkip;
}
/**
* Reads as much from the file as possible to fill the given array.
*
*
* This method may invoke read repeatedly to fill the array and
* only read less bytes than the length of the array if the end of
* the stream has been reached.
*
*
* @param file
* file to read
* @param array
* buffer to fill
* @return the number of bytes actually read
* @throws IOException
* on error
* @since 1.20
*/
public static int read(final File file,final byte[] array) throws IOException{
try (FileInputStream inputStream = new FileInputStream(file)){
return readFully(inputStream, array, 0, array.length);
}
}
/**
* Reads as much from input as possible to fill the given array.
*
*
* This method may invoke read repeatedly to fill the array and
* only read less bytes than the length of the array if the end of
* the stream has been reached.
*
*
* @param input
* stream to read from
* @param array
* buffer to fill
* @return the number of bytes actually read
* @throws IOException
* on error
*/
public static int readFully(final InputStream input,final byte[] array) throws IOException{
return readFully(input, array, 0, array.length);
}
/**
* Reads as much from input as possible to fill the given array
* with the given amount of bytes.
*
*
* This method may invoke read repeatedly to read the bytes and
* only read less bytes than the requested length if the end of
* the stream has been reached.
*
*
* @param input
* stream to read from
* @param array
* buffer to fill
* @param offset
* offset into the buffer to start filling at
* @param len
* of bytes to read
* @return the number of bytes actually read
* @throws IOException
* if an I/O error has occurred
*/
public static int readFully(final InputStream input,final byte[] array,final int offset,final int len) throws IOException{
if (len < 0 || offset < 0 || len + offset > array.length){
throw new IndexOutOfBoundsException();
}
int count = 0, x = 0;
while (count != len){
x = input.read(array, offset + count, len - count);
if (x == -1){
break;
}
count += x;
}
return count;
}
/**
* Reads {@code b.remaining()} bytes from the given channel
* starting at the current channel's position.
*
*
* This method reads repeatedly from the channel until the
* requested number of bytes are read. This method blocks until
* the requested number of bytes are read, the end of the channel
* is detected, or an exception is thrown.
*
*
* @param channel
* the channel to read from
* @param b
* the buffer into which the data is read.
* @throws IOException
* - if an I/O error occurs.
* @throws EOFException
* - if the channel reaches the end before reading all the bytes.
*/
public static void readFully(ReadableByteChannel channel,ByteBuffer b) throws IOException{
final int expectedLength = b.remaining();
int read = 0;
while (read < expectedLength){
int readNow = channel.read(b);
if (readNow <= 0){
break;
}
read += readNow;
}
if (read < expectedLength){
throw new EOFException();
}
}
// toByteArray(InputStream) copied from:
// commons/proper/io/trunk/src/main/java/org/apache/commons/io/IOUtils.java?revision=1428941
// January 8th, 2013
//
// Assuming our copy() works just as well as theirs! :-)
/**
* Gets the contents of an InputStream as a byte[].
*
* This method buffers the input internally, so there is no need to use a
* BufferedInputStream.
*
* @param input
* the InputStream to read from
* @return the requested byte array
* @throws NullPointerException
* if the input is null
* @throws IOException
* if an I/O error occurs
* @since 1.5
*/
public static byte[] toByteArray(final InputStream input) throws IOException{
final ByteArrayOutputStream output = new ByteArrayOutputStream();
copy(input, output);
return output.toByteArray();
}
/**
* Closes the given Closeable and swallows any IOException that may occur.
*
* @param c
* Closeable to close, can be null
* @since 1.7
*/
public static void closeQuietly(final Closeable c){
if (c != null){
try{
c.close();
}catch (final IOException ignored){ // NOPMD NOSONAR
}
}
}
}