Package com.google.common.io

Class ByteSource

  • All Implemented Interfaces:
    InputSupplier<java.io.InputStream>
    public abstract class ByteSource
extends java.lang.Object
implements InputSupplier<java.io.InputStream>
    A readable source of bytes, such as a file. Unlike an InputStream, a ByteSource is not an open, stateful stream for input that can be read and closed. Instead, it is an immutable supplier of InputStream instances.

    ByteSource provides two kinds of methods:

    • Methods that return a stream: These methods should return a new, independent instance each time they are called. The caller is responsible for ensuring that the returned stream is closed.
    • Convenience methods: These are implementations of common operations that are typically implemented by opening a stream using one of the methods in the first category, doing something and finally closing the stream that was opened.
    Since:
    14.0

    • Constructor Summary

      Constructors 
      Constructor Description
      ByteSource()  

    • Method Summary

      All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Deprecated Methods 
      Modifier and Type Method Description
      CharSource asCharSource​(java.nio.charset.Charset charset)
      Returns a CharSource view of this byte source that decodes bytes read from this source as characters using the given Charset.
      static ByteSource concat​(ByteSource... sources)
      Concatenates multiple ByteSource instances into a single source.
      static ByteSource concat​(java.lang.Iterable<? extends ByteSource> sources)
      Concatenates multiple ByteSource instances into a single source.
      static ByteSource concat​(java.util.Iterator<? extends ByteSource> sources)
      Concatenates multiple ByteSource instances into a single source.
      boolean contentEquals​(ByteSource other)
      Checks that the contents of this byte source are equal to the contents of the given byte source.
      long copyTo​(ByteSink sink)
      Copies the contents of this byte source to the given ByteSink.
      long copyTo​(java.io.OutputStream output)
      Copies the contents of this byte source to the given OutputStream.
      static ByteSource empty()
      Returns an immutable ByteSource that contains no bytes.
      java.io.InputStream getInput()
      Deprecated.
      This method is only provided for temporary compatibility with the InputSupplier interface and should not be called directly.
      HashCode hash​(HashFunction hashFunction)
      Hashes the contents of this byte source using the given hash function.
      boolean isEmpty()
      Returns whether the source has zero bytes.
      java.io.InputStream openBufferedStream()
      Opens a new buffered InputStream for reading from this source.
      abstract java.io.InputStream openStream()
      Opens a new InputStream for reading from this source.
      byte[] read()
      Reads the full contents of this byte source as a byte array.
      long size()
      Returns the size of this source in bytes.
      ByteSource slice​(long offset, long length)
      Returns a view of a slice of this byte source that is at most length bytes long starting at the given offset.
      static ByteSource wrap​(byte[] b)
      Returns a view of the given byte array as a ByteSource.

      • Methods inherited from class java.lang.Object

        equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • ByteSource

        public ByteSource()

    • Method Detail

      • asCharSource

        public CharSource asCharSource​(java.nio.charset.Charset charset)
        Returns a CharSource view of this byte source that decodes bytes read from this source as characters using the given Charset.

      • openStream

        public abstract java.io.InputStream openStream()
                                        throws java.io.IOException
        Opens a new InputStream for reading from this source. This method should return a new, independent stream each time it is called.

        The caller is responsible for ensuring that the returned stream is closed.

        Throws:
        java.io.IOException - if an I/O error occurs in the process of opening the stream

      • getInput

        @Deprecated
public final java.io.InputStream getInput()
                                   throws java.io.IOException
        Deprecated.
        This method is only provided for temporary compatibility with the InputSupplier interface and should not be called directly. Use openStream() instead.
        This method is a temporary method provided for easing migration from suppliers to sources and sinks.
        Specified by:
        getInput in interface InputSupplier<java.io.InputStream>
        Throws:
        java.io.IOException
        Since:
        15.0

      • openBufferedStream

        public java.io.InputStream openBufferedStream()
                                       throws java.io.IOException
        Opens a new buffered InputStream for reading from this source. The returned stream is not required to be a BufferedInputStream in order to allow implementations to simply delegate to openStream() when the stream returned by that method does not benefit from additional buffering (for example, a ByteArrayInputStream). This method should return a new, independent stream each time it is called.

        The caller is responsible for ensuring that the returned stream is closed.

        Throws:
        java.io.IOException - if an I/O error occurs in the process of opening the stream
        Since:
        15.0 (in 14.0 with return type BufferedInputStream)

      • slice

        public ByteSource slice​(long offset,
                        long length)
        Returns a view of a slice of this byte source that is at most length bytes long starting at the given offset.
        Throws:
        java.lang.IllegalArgumentException - if offset or length is negative

      • isEmpty

        public boolean isEmpty()
                throws java.io.IOException
        Returns whether the source has zero bytes. The default implementation is to open a stream and check for EOF.
        Throws:
        java.io.IOException - if an I/O error occurs
        Since:
        15.0

      • size

        public long size()
          throws java.io.IOException
        Returns the size of this source in bytes. For most implementations, this is a heavyweight operation that will open a stream, read (or skip, if possible) to the end of the stream and return the total number of bytes that were read.

        For some sources, such as a file, this method may use a more efficient implementation. Note that in such cases, it is possible that this method will return a different number of bytes than would be returned by reading all of the bytes (for example, some special files may return a size of 0 despite actually having content when read).

        In either case, if this is a mutable source such as a file, the size it returns may not be the same number of bytes a subsequent read would return.

        Throws:
        java.io.IOException - if an I/O error occurs in the process of reading the size of this source

      • copyTo

        public long copyTo​(java.io.OutputStream output)
            throws java.io.IOException
        Copies the contents of this byte source to the given OutputStream. Does not close output.
        Throws:
        java.io.IOException - if an I/O error occurs in the process of reading from this source or writing to output

      • copyTo

        public long copyTo​(ByteSink sink)
            throws java.io.IOException
        Copies the contents of this byte source to the given ByteSink.
        Throws:
        java.io.IOException - if an I/O error occurs in the process of reading from this source or writing to sink

      • read

        public byte[] read()
            throws java.io.IOException
        Reads the full contents of this byte source as a byte array.
        Throws:
        java.io.IOException - if an I/O error occurs in the process of reading from this source

      • hash

        public HashCode hash​(HashFunction hashFunction)
              throws java.io.IOException
        Hashes the contents of this byte source using the given hash function.
        Throws:
        java.io.IOException - if an I/O error occurs in the process of reading from this source

      • contentEquals

        public boolean contentEquals​(ByteSource other)
                      throws java.io.IOException
        Checks that the contents of this byte source are equal to the contents of the given byte source.
        Throws:
        java.io.IOException - if an I/O error occurs in the process of reading from this source or other

      • concat

        public static ByteSource concat​(java.lang.Iterable<? extends ByteSource> sources)
        Concatenates multiple ByteSource instances into a single source. Streams returned from the source will contain the concatenated data from the streams of the underlying sources.

        Only one underlying stream will be open at a time. Closing the concatenated stream will close the open underlying stream.

        Parameters:
        sources - the sources to concatenate
        Returns:
        a ByteSource containing the concatenated data
        Since:
        15.0

      • concat

        public static ByteSource concat​(java.util.Iterator<? extends ByteSource> sources)
        Concatenates multiple ByteSource instances into a single source. Streams returned from the source will contain the concatenated data from the streams of the underlying sources.

        Only one underlying stream will be open at a time. Closing the concatenated stream will close the open underlying stream.

        Note: The input Iterator will be copied to an ImmutableList when this method is called. This will fail if the iterator is infinite and may cause problems if the iterator eagerly fetches data for each source when iterated (rather than producing sources that only load data through their streams). Prefer using the concat(Iterable) overload if possible.

        Parameters:
        sources - the sources to concatenate
        Returns:
        a ByteSource containing the concatenated data
        Throws:
        java.lang.NullPointerException - if any of sources is null
        Since:
        15.0

      • concat

        public static ByteSource concat​(ByteSource... sources)
        Concatenates multiple ByteSource instances into a single source. Streams returned from the source will contain the concatenated data from the streams of the underlying sources.

        Only one underlying stream will be open at a time. Closing the concatenated stream will close the open underlying stream.

        Parameters:
        sources - the sources to concatenate
        Returns:
        a ByteSource containing the concatenated data
        Throws:
        java.lang.NullPointerException - if any of sources is null
        Since:
        15.0

      • wrap

        public static ByteSource wrap​(byte[] b)
        Returns a view of the given byte array as a ByteSource. To view only a specific range in the array, use ByteSource.wrap(b).slice(offset, length).
        Since:
        15.0 (since 14.0 as ByteStreams.asByteSource(byte[])).

      • empty

        public static ByteSource empty()
        Returns an immutable ByteSource that contains no bytes.
        Since:
        15.0