Java InputStream Copy copyLarge(InputStream input, OutputStream output, final long inputOffset, final long length, byte[] buffer)

Here you can find the source of copyLarge(InputStream input, OutputStream output, final long inputOffset, final long length, byte[] buffer)

Description

Copy some or all bytes from a large (over 2GB) InputStream to an OutputStream, optionally skipping input bytes.

License

Apache License

Parameter

Parameter Description
input the <code>InputStream</code> to read from
output the <code>OutputStream</code> to write to
inputOffset : number of bytes to skip from input before copying -ve values are ignored
length : number of bytes to copy. -ve means all
buffer the buffer to use for the copy

Exception

Parameter Description
NullPointerException if the input or output is null
IOException if an I/O error occurs

Return

the number of bytes copied

Declaration

public static long copyLarge(InputStream input, OutputStream output, final long inputOffset, final long length,
        byte[] buffer) throws IOException 

Method Source Code

//package com.java2s;
/*/*from w  ww  .  jav a2s.  c  om*/
 * 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.
 */

import java.io.EOFException;

import java.io.IOException;
import java.io.InputStream;

import java.io.OutputStream;

import java.io.Reader;
import java.io.Writer;

public class Main {
    private static final int EOF = -1;
    /**
     * The default buffer size ({@value}) to use for 
     * {@link #copyLarge(InputStream, OutputStream)}
     * and
     * {@link #copyLarge(Reader, Writer)}
     */
    private static final int DEFAULT_BUFFER_SIZE = 1024 * 4;
    /**
     * The default buffer size to use for the skip() methods.
     */
    private static final int SKIP_BUFFER_SIZE = 2048;
    private static char[] SKIP_CHAR_BUFFER;
    private static byte[] SKIP_BYTE_BUFFER;

    /**
     * Copy bytes from a large (over 2GB) <code>InputStream</code> to an
     * <code>OutputStream</code>.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedInputStream</code>.
     * <p>
     * The buffer size is given by {@link #DEFAULT_BUFFER_SIZE}.
     * 
     * @param input  the <code>InputStream</code> to read from
     * @param output  the <code>OutputStream</code> to write to
     * @return the number of bytes copied
     * @throws NullPointerException if the input or output is null
     * @throws IOException if an I/O error occurs
     * @since 1.3
     */
    public static long copyLarge(InputStream input, OutputStream output) throws IOException {
        return copyLarge(input, output, new byte[DEFAULT_BUFFER_SIZE]);
    }

    /**
     * Copy bytes from a large (over 2GB) <code>InputStream</code> to an
     * <code>OutputStream</code>.
     * <p>
     * This method uses the provided buffer, so there is no need to use a
     * <code>BufferedInputStream</code>.
     * <p>
     * 
     * @param input  the <code>InputStream</code> to read from
     * @param output  the <code>OutputStream</code> to write to
     * @param buffer the buffer to use for the copy
     * @return the number of bytes copied
     * @throws NullPointerException if the input or output is null
     * @throws IOException if an I/O error occurs
     * @since 2.2
     */
    public static long copyLarge(InputStream input, OutputStream output, byte[] buffer) throws IOException {
        long count = 0;
        int n = 0;
        while (EOF != (n = input.read(buffer))) {
            output.write(buffer, 0, n);
            count += n;
        }
        return count;
    }

    /**
     * Copy some or all bytes from a large (over 2GB) <code>InputStream</code> to an
     * <code>OutputStream</code>, optionally skipping input bytes.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedInputStream</code>.
     * <p>
     * The buffer size is given by {@link #DEFAULT_BUFFER_SIZE}.
     * 
     * @param input  the <code>InputStream</code> to read from
     * @param output  the <code>OutputStream</code> to write to
     * @param inputOffset : number of bytes to skip from input before copying
     *         -ve values are ignored
     * @param length : number of bytes to copy. -ve means all
     * @return the number of bytes copied
     * @throws NullPointerException if the input or output is null
     * @throws IOException if an I/O error occurs
     * @since 2.2
     */
    public static long copyLarge(InputStream input, OutputStream output, long inputOffset, long length)
            throws IOException {
        return copyLarge(input, output, inputOffset, length, new byte[DEFAULT_BUFFER_SIZE]);
    }

    /**
     * Copy some or all bytes from a large (over 2GB) <code>InputStream</code> to an
     * <code>OutputStream</code>, optionally skipping input bytes.
     * <p>
     * This method uses the provided buffer, so there is no need to use a
     * <code>BufferedInputStream</code>.
     * <p>
     * 
     * @param input  the <code>InputStream</code> to read from
     * @param output  the <code>OutputStream</code> to write to
     * @param inputOffset : number of bytes to skip from input before copying
     *         -ve values are ignored
     * @param length : number of bytes to copy. -ve means all
     * @param buffer the buffer to use for the copy
     *
     * @return the number of bytes copied
     * @throws NullPointerException if the input or output is null
     * @throws IOException if an I/O error occurs
     * @since 2.2
     */
    public static long copyLarge(InputStream input, OutputStream output, final long inputOffset, final long length,
            byte[] buffer) throws IOException {
        if (inputOffset > 0) {
            skipFully(input, inputOffset);
        }
        if (length == 0) {
            return 0;
        }
        final int bufferLength = buffer.length;
        int bytesToRead = bufferLength;
        if (length > 0 && length < bufferLength) {
            bytesToRead = (int) length;
        }
        int read;
        long totalRead = 0;
        while (bytesToRead > 0 && EOF != (read = input.read(buffer, 0, bytesToRead))) {
            output.write(buffer, 0, read);
            totalRead += read;
            if (length > 0) { // only adjust length if not reading to the end
                // Note the cast must work because buffer.length is an integer
                bytesToRead = (int) Math.min(length - totalRead, bufferLength);
            }
        }
        return totalRead;
    }

    /**
     * Copy chars from a large (over 2GB) <code>Reader</code> to a <code>Writer</code>.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedReader</code>.
     * <p>
     * The buffer size is given by {@link #DEFAULT_BUFFER_SIZE}.
     *
     * @param input  the <code>Reader</code> to read from
     * @param output  the <code>Writer</code> to write to
     * @return the number of characters copied
     * @throws NullPointerException if the input or output is null
     * @throws IOException if an I/O error occurs
     * @since 1.3
     */
    public static long copyLarge(Reader input, Writer output) throws IOException {
        return copyLarge(input, output, new char[DEFAULT_BUFFER_SIZE]);
    }

    /**
     * Copy chars from a large (over 2GB) <code>Reader</code> to a <code>Writer</code>.
     * <p>
     * This method uses the provided buffer, so there is no need to use a
     * <code>BufferedReader</code>.
     * <p>
     *
     * @param input  the <code>Reader</code> to read from
     * @param output  the <code>Writer</code> to write to
     * @param buffer the buffer to be used for the copy
     * @return the number of characters copied
     * @throws NullPointerException if the input or output is null
     * @throws IOException if an I/O error occurs
     * @since 2.2
     */
    public static long copyLarge(Reader input, Writer output, char[] buffer) throws IOException {
        long count = 0;
        int n = 0;
        while (EOF != (n = input.read(buffer))) {
            output.write(buffer, 0, n);
            count += n;
        }
        return count;
    }

    /**
     * Copy some or all chars from a large (over 2GB) <code>InputStream</code> to an
     * <code>OutputStream</code>, optionally skipping input chars.
     * <p>
     * This method buffers the input internally, so there is no need to use a
     * <code>BufferedReader</code>.
     * <p>
     * The buffer size is given by {@link #DEFAULT_BUFFER_SIZE}.
     * 
     * @param input  the <code>Reader</code> to read from
     * @param output  the <code>Writer</code> to write to
     * @param inputOffset : number of chars to skip from input before copying
     *         -ve values are ignored
     * @param length : number of chars to copy. -ve means all
     * @return the number of chars copied
     * @throws NullPointerException if the input or output is null
     * @throws IOException if an I/O error occurs
     * @since 2.2
     */
    public static long copyLarge(Reader input, Writer output, final long inputOffset, final long length)
            throws IOException {
        return copyLarge(input, output, inputOffset, length, new char[DEFAULT_BUFFER_SIZE]);
    }

    /**
     * Copy some or all chars from a large (over 2GB) <code>InputStream</code> to an
     * <code>OutputStream</code>, optionally skipping input chars.
     * <p>
     * This method uses the provided buffer, so there is no need to use a
     * <code>BufferedReader</code>.
     * <p>
     * 
     * @param input  the <code>Reader</code> to read from
     * @param output  the <code>Writer</code> to write to
     * @param inputOffset : number of chars to skip from input before copying
     *         -ve values are ignored
     * @param length : number of chars to copy. -ve means all
     * @param buffer the buffer to be used for the copy
     * @return the number of chars copied
     * @throws NullPointerException if the input or output is null
     * @throws IOException if an I/O error occurs
     * @since 2.2
     */
    public static long copyLarge(Reader input, Writer output, final long inputOffset, final long length,
            char[] buffer) throws IOException {
        if (inputOffset > 0) {
            skipFully(input, inputOffset);
        }
        if (length == 0) {
            return 0;
        }
        int bytesToRead = buffer.length;
        if (length > 0 && length < buffer.length) {
            bytesToRead = (int) length;
        }
        int read;
        long totalRead = 0;
        while (bytesToRead > 0 && EOF != (read = input.read(buffer, 0, bytesToRead))) {
            output.write(buffer, 0, read);
            totalRead += read;
            if (length > 0) { // only adjust length if not reading to the end
                // Note the cast must work because buffer.length is an integer
                bytesToRead = (int) Math.min(length - totalRead, buffer.length);
            }
        }
        return totalRead;
    }

    /**
     * Read characters from an input character stream.
     * This implementation guarantees that it will read as many characters
     * as possible before giving up; this may not always be the case for
     * subclasses of {@link Reader}.
     * 
     * @param input where to read input from
     * @param buffer destination
     * @param offset inital offset into buffer
     * @param length length to read, must be >= 0
     * @return actual length read; may be less than requested if EOF was reached
     * @throws IOException if a read error occurs
     * @since 2.2
     */
    public static int read(Reader input, char[] buffer, int offset, int length) throws IOException {
        if (length < 0) {
            throw new IllegalArgumentException("Length must not be negative: " + length);
        }
        int remaining = length;
        while (remaining > 0) {
            int location = length - remaining;
            int count = input.read(buffer, offset + location, remaining);
            if (EOF == count) { // EOF
                break;
            }
            remaining -= count;
        }
        return length - remaining;
    }

    /**
     * Read characters from an input character stream.
     * This implementation guarantees that it will read as many characters
     * as possible before giving up; this may not always be the case for
     * subclasses of {@link Reader}.
     * 
     * @param input where to read input from
     * @param buffer destination
     * @return actual length read; may be less than requested if EOF was reached
     * @throws IOException if a read error occurs
     * @since 2.2
     */
    public static int read(Reader input, char[] buffer) throws IOException {
        return read(input, buffer, 0, buffer.length);
    }

    /**
     * Read bytes from an input stream.
     * This implementation guarantees that it will read as many bytes
     * as possible before giving up; this may not always be the case for
     * subclasses of {@link InputStream}.
     * 
     * @param input where to read input from
     * @param buffer destination
     * @param offset inital offset into buffer
     * @param length length to read, must be >= 0
     * @return actual length read; may be less than requested if EOF was reached
     * @throws IOException if a read error occurs
     * @since 2.2
     */
    public static int read(InputStream input, byte[] buffer, int offset, int length) throws IOException {
        if (length < 0) {
            throw new IllegalArgumentException("Length must not be negative: " + length);
        }
        int remaining = length;
        while (remaining > 0) {
            int location = length - remaining;
            int count = input.read(buffer, offset + location, remaining);
            if (EOF == count) { // EOF
                break;
            }
            remaining -= count;
        }
        return length - remaining;
    }

    /**
     * Read bytes from an input stream.
     * This implementation guarantees that it will read as many bytes
     * as possible before giving up; this may not always be the case for
     * subclasses of {@link InputStream}.
     * 
     * @param input where to read input from
     * @param buffer destination
     * @return actual length read; may be less than requested if EOF was reached
     * @throws IOException if a read error occurs
     * @since 2.2
     */
    public static int read(InputStream input, byte[] buffer) throws IOException {
        return read(input, buffer, 0, buffer.length);
    }

    /**
     * Writes bytes from a <code>byte[]</code> to an <code>OutputStream</code>.
     * 
     * @param data  the byte array to write, do not modify during output,
     * null ignored
     * @param output  the <code>OutputStream</code> to write to
     * @throws NullPointerException if output is null
     * @throws IOException if an I/O error occurs
     * @since 1.1
     */
    public static void write(byte[] data, OutputStream output) throws IOException {
        if (data != null) {
            output.write(data);
        }
    }

    /**
     * Writes bytes from a <code>byte[]</code> to chars on a <code>Writer</code>
     * using the default character encoding of the platform.
     * <p>
     * This method uses {@link String#String(byte[])}.
     * 
     * @param data  the byte array to write, do not modify during output,
     * null ignored
     * @param output  the <code>Writer</code> to write to
     * @throws NullPointerException if output is null
     * @throws IOException if an I/O error occurs
     * @since 1.1
     */
    public static void write(byte[] data, Writer output) throws IOException {
        if (data != null) {
            output.write(new String(data));
        }
    }

    /**
     * Writes bytes from a <code>byte[]</code> to chars on a <code>Writer</code>
     * using the specified character encoding.
     * <p>
     * Character encoding names can be found at
     * <a href="http://www.iana.org/assignments/character-sets">IANA</a>.
     * <p>
     * This method uses {@link String#String(byte[], String)}.
     * 
     * @param data  the byte array to write, do not modify during output,
     * null ignored
     * @param output  the <code>Writer</code> to write to
     * @param encoding  the encoding to use, null means platform default
     * @throws NullPointerException if output is null
     * @throws IOException if an I/O error occurs
     * @since 1.1
     */
    public static void write(byte[] data, Writer output, String encoding) throws IOException {
        if (data != null) {
            if (encoding == null) {
                write(data, output);
            } else {
                output.write(new String(data, encoding));
            }
        }
    }

    /**
     * Writes chars from a <code>char[]</code> to a <code>Writer</code>
     * using the default character encoding of the platform.
     * 
     * @param data  the char array to write, do not modify during output,
     * null ignored
     * @param output  the <code>Writer</code> to write to
     * @throws NullPointerException if output is null
     * @throws IOException if an I/O error occurs
     * @since 1.1
     */
    public static void write(char[] data, Writer output) throws IOException {
        if (data != null) {
            output.write(data);
        }
    }

    /**
     * Writes chars from a <code>char[]</code> to bytes on an
     * <code>OutputStream</code>.
     * <p>
     * This method uses {@link String#String(char[])} and
     * {@link String#getBytes()}.
     * 
     * @param data  the char array to write, do not modify during output,
     * null ignored
     * @param output  the <code>OutputStream</code> to write to
     * @throws NullPointerException if output is null
     * @throws IOException if an I/O error occurs
     * @since 1.1
     */
    public static void write(char[] data, OutputStream output) throws IOException {
        if (data != null) {
            output.write(new String(data).getBytes());
        }
    }

    /**
     * Writes chars from a <code>char[]</code> to bytes on an
     * <code>OutputStream</code> using the specified character encoding.
     * <p>
     * Character encoding names can be found at
     * <a href="http://www.iana.org/assignments/character-sets">IANA</a>.
     * <p>
     * This method uses {@link String#String(char[])} and
     * {@link String#getBytes(String)}.
     * 
     * @param data  the char array to write, do not modify during output,
     * null ignored
     * @param output  the <code>OutputStream</code> to write to
     * @param encoding  the encoding to use, null means platform default
     * @throws NullPointerException if output is null
     * @throws IOException if an I/O error occurs
     * @since 1.1
     */
    public static void write(char[] data, OutputStream output, String encoding) throws IOException {
        if (data != null) {
            if (encoding == null) {
                write(data, output);
            } else {
                output.write(new String(data).getBytes(encoding));
            }
        }
    }

    /**
     * Writes chars from a <code>CharSequence</code> to a <code>Writer</code>.
     * 
     * @param data  the <code>CharSequence</code> to write, null ignored
     * @param output  the <code>Writer</code> to write to
     * @throws NullPointerException if output is null
     * @throws IOException if an I/O error occurs
     * @since 2.0
     */
    public static void write(CharSequence data, Writer output) throws IOException {
        if (data != null) {
            write(data.toString(), output);
        }
    }

    /**
     * Writes chars from a <code>CharSequence</code> to bytes on an
     * <code>OutputStream</code> using the default character encoding of the
     * platform.
     * <p>
     * This method uses {@link String#getBytes()}.
     * 
     * @param data  the <code>CharSequence</code> to write, null ignored
     * @param output  the <code>OutputStream</code> to write to
     * @throws NullPointerException if output is null
     * @throws IOException if an I/O error occurs
     * @since 2.0
     */
    public static void write(CharSequence data, OutputStream output) throws IOException {
        if (data != null) {
            write(data.toString(), output);
        }
    }

    /**
     * Writes chars from a <code>CharSequence</code> to bytes on an
     * <code>OutputStream</code> using the specified character encoding.
     * <p>
     * Character encoding names can be found at
     * <a href="http://www.iana.org/assignments/character-sets">IANA</a>.
     * <p>
     * This method uses {@link String#getBytes(String)}.
     * 
     * @param data  the <code>CharSequence</code> to write, null ignored
     * @param output  the <code>OutputStream</code> to write to
     * @param encoding  the encoding to use, null means platform default
     * @throws NullPointerException if output is null
     * @throws IOException if an I/O error occurs
     * @since 2.0
     */
    public static void write(CharSequence data, OutputStream output, String encoding) throws IOException {
        if (data != null) {
            write(data.toString(), output, encoding);
        }
    }

    /**
     * Writes chars from a <code>String</code> to a <code>Writer</code>.
     * 
     * @param data  the <code>String</code> to write, null ignored
     * @param output  the <code>Writer</code> to write to
     * @throws NullPointerException if output is null
     * @throws IOException if an I/O error occurs
     * @since 1.1
     */
    public static void write(String data, Writer output) throws IOException {
        if (data != null) {
            output.write(data);
        }
    }

    /**
     * Writes chars from a <code>String</code> to bytes on an
     * <code>OutputStream</code> using the default character encoding of the
     * platform.
     * <p>
     * This method uses {@link String#getBytes()}.
     * 
     * @param data  the <code>String</code> to write, null ignored
     * @param output  the <code>OutputStream</code> to write to
     * @throws NullPointerException if output is null
     * @throws IOException if an I/O error occurs
     * @since 1.1
     */
    public static void write(String data, OutputStream output) throws IOException {
        if (data != null) {
            output.write(data.getBytes());
        }
    }

    /**
     * Writes chars from a <code>String</code> to bytes on an
     * <code>OutputStream</code> using the specified character encoding.
     * <p>
     * Character encoding names can be found at
     * <a href="http://www.iana.org/assignments/character-sets">IANA</a>.
     * <p>
     * This method uses {@link String#getBytes(String)}.
     * 
     * @param data  the <code>String</code> to write, null ignored
     * @param output  the <code>OutputStream</code> to write to
     * @param encoding  the encoding to use, null means platform default
     * @throws NullPointerException if output is null
     * @throws IOException if an I/O error occurs
     * @since 1.1
     */
    public static void write(String data, OutputStream output, String encoding) throws IOException {
        if (data != null) {
            if (encoding == null) {
                write(data, output);
            } else {
                output.write(data.getBytes(encoding));
            }
        }
    }

    /**
     * Writes chars from a <code>StringBuffer</code> to a <code>Writer</code>.
     * 
     * @param data  the <code>StringBuffer</code> to write, null ignored
     * @param output  the <code>Writer</code> to write to
     * @throws NullPointerException if output is null
     * @throws IOException if an I/O error occurs
     * @since 1.1
     * @deprecated replaced by write(CharSequence, Writer)
     */
    @Deprecated
    public static void write(StringBuffer data, Writer output) throws IOException {
        if (data != null) {
            output.write(data.toString());
        }
    }

    /**
     * Writes chars from a <code>StringBuffer</code> to bytes on an
     * <code>OutputStream</code> using the default character encoding of the
     * platform.
     * <p>
     * This method uses {@link String#getBytes()}.
     * 
     * @param data  the <code>StringBuffer</code> to write, null ignored
     * @param output  the <code>OutputStream</code> to write to
     * @throws NullPointerException if output is null
     * @throws IOException if an I/O error occurs
     * @since 1.1
     * @deprecated replaced by write(CharSequence, OutputStream)
     */
    @Deprecated
    public static void write(StringBuffer data, OutputStream output) throws IOException {
        if (data != null) {
            output.write(data.toString().getBytes());
        }
    }

    /**
     * Writes chars from a <code>StringBuffer</code> to bytes on an
     * <code>OutputStream</code> using the specified character encoding.
     * <p>
     * Character encoding names can be found at
     * <a href="http://www.iana.org/assignments/character-sets">IANA</a>.
     * <p>
     * This method uses {@link String#getBytes(String)}.
     * 
     * @param data  the <code>StringBuffer</code> to write, null ignored
     * @param output  the <code>OutputStream</code> to write to
     * @param encoding  the encoding to use, null means platform default
     * @throws NullPointerException if output is null
     * @throws IOException if an I/O error occurs
     * @since 1.1
     * @deprecated replaced by write(CharSequence, OutputStream, String)
     */
    @Deprecated
    public static void write(StringBuffer data, OutputStream output, String encoding) throws IOException {
        if (data != null) {
            if (encoding == null) {
                write(data, output);
            } else {
                output.write(data.toString().getBytes(encoding));
            }
        }
    }

    /**
     * Skip the requested number of bytes or fail if there are not enough left.
     * <p>
     * This allows for the possibility that {@link InputStream#skip(long)} may
     * not skip as many bytes as requested (most likely because of reaching EOF).
     * 
     * @param input stream to skip
     * @param toSkip the number of bytes to skip
     * @see InputStream#skip(long)
     * 
     * @throws IOException if there is a problem reading the file
     * @throws IllegalArgumentException if toSkip is negative
     * @throws EOFException if the number of bytes skipped was incorrect 
     * @since 2.0
     */
    public static void skipFully(InputStream input, long toSkip) throws IOException {
        if (toSkip < 0) {
            throw new IllegalArgumentException("Bytes to skip must not be negative: " + toSkip);
        }
        long skipped = skip(input, toSkip);
        if (skipped != toSkip) {
            throw new EOFException("Bytes to skip: " + toSkip + " actual: " + skipped);
        }
    }

    /**
     * Skip the requested number of characters or fail if there are not enough left.
     * <p>
     * This allows for the possibility that {@link Reader#skip(long)} may
     * not skip as many characters as requested (most likely because of reaching EOF).
     * 
     * @param input stream to skip
     * @param toSkip the number of characters to skip
     * @see Reader#skip(long)
     * 
     * @throws IOException if there is a problem reading the file
     * @throws IllegalArgumentException if toSkip is negative
     * @throws EOFException if the number of characters skipped was incorrect
     * @since 2.0
     */
    public static void skipFully(Reader input, long toSkip) throws IOException {
        long skipped = skip(input, toSkip);
        if (skipped != toSkip) {
            throw new EOFException("Chars to skip: " + toSkip + " actual: " + skipped);
        }
    }

    /**
     * Get the contents of a <code>byte[]</code> as a String
     * using the default character encoding of the platform.
     * 
     * @param input the byte array to read from
     * @return the requested String
     * @throws NullPointerException if the input is null
     * @throws IOException if an I/O error occurs (never occurs)
     * @deprecated Use {@link String#String(byte[])}
     */
    @Deprecated
    public static String toString(byte[] input) throws IOException {
        return new String(input);
    }

    /**
     * Get the contents of a <code>byte[]</code> as a String
     * using the specified character encoding.
     * <p>
     * Character encoding names can be found at
     * <a href="http://www.iana.org/assignments/character-sets">IANA</a>.
     * 
     * @param input the byte array to read from
     * @param encoding  the encoding to use, null means platform default
     * @return the requested String
     * @throws NullPointerException if the input is null
     * @throws IOException if an I/O error occurs (never occurs)
     * @deprecated Use {@link String#String(byte[],String)}
     */
    @Deprecated
    public static String toString(byte[] input, String encoding) throws IOException {
        if (encoding == null) {
            return new String(input);
        } else {
            return new String(input, encoding);
        }
    }

    /**
     * Skip bytes from an input byte stream.
     * This implementation guarantees that it will read as many bytes
     * as possible before giving up; this may not always be the case for
     * subclasses of {@link Reader}.
     *   
     * @param input byte stream to skip
     * @param toSkip number of bytes to skip.
     * @return number of bytes actually skipped.
     * 
     * @see InputStream#skip(long)
     * 
     * @throws IOException if there is a problem reading the file
     * @throws IllegalArgumentException if toSkip is negative
     * @since 2.0
     */
    public static long skip(InputStream input, long toSkip) throws IOException {
        if (toSkip < 0) {
            throw new IllegalArgumentException("Skip count must be non-negative, actual: " + toSkip);
        }
        /*
         * N.B. no need to synchronize this because: - we don't care if the buffer is created multiple times (the data
         * is ignored) - we always use the same size buffer, so if it it is recreated it will still be OK (if the buffer
         * size were variable, we would need to synch. to ensure some other thread did not create a smaller one)
         */
        if (SKIP_BYTE_BUFFER == null) {
            SKIP_BYTE_BUFFER = new byte[SKIP_BUFFER_SIZE];
        }
        long remain = toSkip;
        while (remain > 0) {
            long n = input.read(SKIP_BYTE_BUFFER, 0, (int) Math.min(remain, SKIP_BUFFER_SIZE));
            if (n < 0) { // EOF
                break;
            }
            remain -= n;
        }
        return toSkip - remain;
    }

    /**
     * Skip characters from an input character stream.
     * This implementation guarantees that it will read as many characters
     * as possible before giving up; this may not always be the case for
     * subclasses of {@link Reader}.
     *   
     * @param input character stream to skip
     * @param toSkip number of characters to skip.
     * @return number of characters actually skipped.
     * 
     * @see Reader#skip(long)
     * 
     * @throws IOException if there is a problem reading the file
     * @throws IllegalArgumentException if toSkip is negative
     * @since 2.0
     */
    public static long skip(Reader input, long toSkip) throws IOException {
        if (toSkip < 0) {
            throw new IllegalArgumentException("Skip count must be non-negative, actual: " + toSkip);
        }
        /*
         * N.B. no need to synchronize this because: - we don't care if the buffer is created multiple times (the data
         * is ignored) - we always use the same size buffer, so if it it is recreated it will still be OK (if the buffer
         * size were variable, we would need to synch. to ensure some other thread did not create a smaller one)
         */
        if (SKIP_CHAR_BUFFER == null) {
            SKIP_CHAR_BUFFER = new char[SKIP_BUFFER_SIZE];
        }
        long remain = toSkip;
        while (remain > 0) {
            long n = input.read(SKIP_CHAR_BUFFER, 0, (int) Math.min(remain, SKIP_BUFFER_SIZE));
            if (n < 0) { // EOF
                break;
            }
            remain -= n;
        }
        return toSkip - remain;
    }
}

Related

  1. copyLarge(InputStream input, OutputStream output)
  2. copyLarge(InputStream input, OutputStream output, byte[] buffer)
  3. copyLarge(InputStream input, OutputStream output, byte[] buffer)
  4. copyLarge(InputStream input, OutputStream output, byte[] buffer)
  5. copyLarge(InputStream input, OutputStream output, final long inputOffset, final long length, byte[] buffer)
  6. copyLarge(InputStream input, OutputStream output, long limit)
  7. copyStream(final BufferedReader in, final PrintWriter out, final String[] mapFrom, String[] mapTo)
  8. copyStream(InputStream is)
  9. copyStream(InputStream is)