Package org.apache.commons.io.input

Class ReaderInputStream

  • All Implemented Interfaces:
    java.io.Closeable, java.lang.AutoCloseable
    public class ReaderInputStream
extends java.io.InputStream
    InputStream implementation that reads a character stream from a Reader and transforms it to a byte stream using a specified charset encoding. The stream is transformed using a CharsetEncoder object, guaranteeing that all charset encodings supported by the JRE are handled correctly. In particular for charsets such as UTF-16, the implementation ensures that one and only one byte order marker is produced.

    Since in general it is not possible to predict the number of characters to be read from the Reader to satisfy a read request on the ReaderInputStream, all reads from the Reader are buffered. There is therefore no well defined correlation between the current position of the Reader and that of the ReaderInputStream. This also implies that in general there is no need to wrap the underlying Reader in a BufferedReader.

    ReaderInputStream implements the inverse transformation of InputStreamReader; in the following example, reading from in2 would return the same byte sequence as reading from in (provided that the initial byte sequence is legal with respect to the charset encoding):

    To build an instance, see ReaderInputStream.Builder. 

     InputStream inputStream = ...
 Charset cs = ...
 InputStreamReader reader = new InputStreamReader(inputStream, cs);
 ReaderInputStream in2 = ReaderInputStream.builder()
   .setReader(reader)
   .setCharset(cs)
   .get();

    ReaderInputStream implements the same transformation as OutputStreamWriter, except that the control flow is reversed: both classes transform a character stream into a byte stream, but OutputStreamWriter pushes data to the underlying stream, while ReaderInputStream pulls it from the underlying stream.

    Note that while there are use cases where there is no alternative to using this class, very often the need to use this class is an indication of a flaw in the design of the code. This class is typically used in situations where an existing API only accepts an InputStream, but where the most natural way to produce the data is as a character stream, i.e. by providing a Reader instance. An example of a situation where this problem may appear is when implementing the javax.activation.DataSource interface from the Java Activation Framework.

    The InputStream.available() method of this class always returns 0. The methods InputStream.mark(int) and InputStream.reset() are not supported.

    Instances of ReaderInputStream are not thread safe.

    Since:
    2.0
    See Also:
    WriterOutputStream

    • Constructor Summary

      Constructors 
      Constructor Description
      ReaderInputStream​(java.io.Reader reader)
      Deprecated.
      Use builder() instead
      ReaderInputStream​(java.io.Reader reader, java.lang.String charsetName)
      Deprecated.
      Use builder() instead
      ReaderInputStream​(java.io.Reader reader, java.lang.String charsetName, int bufferSize)
      Deprecated.
      Use builder() instead
      ReaderInputStream​(java.io.Reader reader, java.nio.charset.Charset charset)
      Deprecated.
      Use builder() instead, will be protected for subclasses.
      ReaderInputStream​(java.io.Reader reader, java.nio.charset.CharsetEncoder charsetEncoder)
      Deprecated.
      Use builder() instead
      ReaderInputStream​(java.io.Reader reader, java.nio.charset.CharsetEncoder charsetEncoder, int bufferSize)
      Deprecated.
      Use builder() instead
      ReaderInputStream​(java.io.Reader reader, java.nio.charset.Charset charset, int bufferSize)
      Deprecated.
      Use builder() instead

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      static ReaderInputStream.Builder builder()
      Constructs a new ReaderInputStream.Builder.
      void close()
      Closes the stream.
      int read()
      Reads a single byte.
      int read​(byte[] b)
      Reads the specified number of bytes into an array.
      int read​(byte[] array, int off, int len)
      Reads the specified number of bytes into an array.

      • Methods inherited from class java.io.InputStream

        available, mark, markSupported, nullInputStream, readAllBytes, readNBytes, readNBytes, reset, skip, transferTo

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • ReaderInputStream

        @Deprecated
public ReaderInputStream​(java.io.Reader reader)
        Deprecated.
        Use builder() instead
        Constructs a new ReaderInputStream that uses the default character encoding with a default input buffer size of 8192 characters.
        Parameters:
        reader - the target Reader

      • ReaderInputStream

        @Deprecated
public ReaderInputStream​(java.io.Reader reader,
                         java.nio.charset.Charset charset)
        Deprecated.
        Use builder() instead, will be protected for subclasses.
        Constructs a new ReaderInputStream with a default input buffer size of 8192 characters.

        The encoder created for the specified charset will use CodingErrorAction.REPLACE for malformed input and unmappable characters.

        Parameters:
        reader - the target Reader
        charset - the charset encoding

      • ReaderInputStream

        @Deprecated
public ReaderInputStream​(java.io.Reader reader,
                         java.nio.charset.Charset charset,
                         int bufferSize)
        Deprecated.
        Use builder() instead
        Constructs a new ReaderInputStream.

        The encoder created for the specified charset will use CodingErrorAction.REPLACE for malformed input and unmappable characters.

        Parameters:
        reader - the target Reader.
        charset - the charset encoding.
        bufferSize - the size of the input buffer in number of characters.

      • ReaderInputStream

        @Deprecated
public ReaderInputStream​(java.io.Reader reader,
                         java.nio.charset.CharsetEncoder charsetEncoder)
        Deprecated.
        Use builder() instead
        Constructs a new ReaderInputStream.

        This constructor does not call reset on the provided encoder. The caller of this constructor should do this when providing an encoder which had already been in use.

        Parameters:
        reader - the target Reader
        charsetEncoder - the charset encoder
        Since:
        2.1

      • ReaderInputStream

        @Deprecated
public ReaderInputStream​(java.io.Reader reader,
                         java.nio.charset.CharsetEncoder charsetEncoder,
                         int bufferSize)
        Deprecated.
        Use builder() instead
        Constructs a new ReaderInputStream.

        This constructor does not call reset on the provided encoder. The caller of this constructor should do this when providing an encoder which had already been in use.

        Parameters:
        reader - the target Reader
        charsetEncoder - the charset encoder, null defaults to the default Charset encoder.
        bufferSize - the size of the input buffer in number of characters
        Since:
        2.1

      • ReaderInputStream

        @Deprecated
public ReaderInputStream​(java.io.Reader reader,
                         java.lang.String charsetName)
        Deprecated.
        Use builder() instead
        Constructs a new ReaderInputStream with a default input buffer size of 8192 characters.

        The encoder created for the specified charset will use CodingErrorAction.REPLACE for malformed input and unmappable characters.

        Parameters:
        reader - the target Reader
        charsetName - the name of the charset encoding

      • ReaderInputStream

        @Deprecated
public ReaderInputStream​(java.io.Reader reader,
                         java.lang.String charsetName,
                         int bufferSize)
        Deprecated.
        Use builder() instead
        Constructs a new ReaderInputStream.

        The encoder created for the specified charset will use CodingErrorAction.REPLACE for malformed input and unmappable characters.

        Parameters:
        reader - the target Reader
        charsetName - the name of the charset encoding, null maps to the default Charset.
        bufferSize - the size of the input buffer in number of characters

    • Method Detail

      • close

        public void close()
           throws java.io.IOException
        Closes the stream. This method will cause the underlying Reader to be closed.
        Specified by:
        close in interface java.lang.AutoCloseable
        Specified by:
        close in interface java.io.Closeable
        Overrides:
        close in class java.io.InputStream
        Throws:
        java.io.IOException - if an I/O error occurs.

      • read

        public int read()
         throws java.io.IOException
        Reads a single byte.
        Specified by:
        read in class java.io.InputStream
        Returns:
        either the byte read or -1 if the end of the stream has been reached
        Throws:
        java.io.IOException - if an I/O error occurs.

      • read

        public int read​(byte[] b)
         throws java.io.IOException
        Reads the specified number of bytes into an array.
        Overrides:
        read in class java.io.InputStream
        Parameters:
        b - the byte array to read into
        Returns:
        the number of bytes read or -1 if the end of the stream has been reached
        Throws:
        java.io.IOException - if an I/O error occurs.

      • read

        public int read​(byte[] array,
                int off,
                int len)
         throws java.io.IOException
        Reads the specified number of bytes into an array.
        Overrides:
        read in class java.io.InputStream
        Parameters:
        array - the byte array to read into
        off - the offset to start reading bytes into
        len - the number of bytes to read
        Returns:
        the number of bytes read or -1 if the end of the stream has been reached
        Throws:
        java.io.IOException - if an I/O error occurs.