Package org.apache.commons.io.input

Class UnsynchronizedBufferedReader

java.lang.Object
java.io.Reader
org.apache.commons.io.input.UnsynchronizedReader
org.apache.commons.io.input.UnsynchronizedBufferedReader
All Implemented Interfaces:
Closeable, AutoCloseable, Readable
public class UnsynchronizedBufferedReader extends UnsynchronizedReader
Wraps an existing Reader and buffers the input without any synchronization. Expensive interaction with the underlying reader is minimized, since most (smaller) requests can be satisfied by accessing the buffer alone. The drawback is that some extra space is required to hold the buffer and that copying takes place when filling that buffer, but this is usually outweighed by the performance benefits.

A typical application pattern for the class looks like this: 


 UnsynchronizedBufferedReader buf = new UnsynchronizedBufferedReader(new FileReader("file"));

Provenance: Apache Harmony's java.io.BufferedReader, renamed, and modified.

Since:
2.17.0
See Also:

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    private char[]
    buf
    The characters that can be read and refilled in bulk.
    private int
    end
     
    private final Reader
    in
     
    private int
    mark
     
    private int
    markLimit
     
    private static final char
    NUL
     
    private int
    pos
     

    Fields inherited from class java.io.Reader

    lock

  • Constructor Summary

    Constructors
    Constructor
    Description
    UnsynchronizedBufferedReader(Reader in)
    Constructs a new BufferedReader on the Reader in.
    UnsynchronizedBufferedReader(Reader in, int size)
    Constructs a new BufferedReader on the Reader in.

  • Method Summary

    Modifier and Type
    Method
    Description
    (package private) final void
    chompNewline()
    Peeks at the next input character, refilling the buffer if necessary.
    void
    close()
    Closes this reader.
    private int
    fillBuf()
    Populates the buffer with data.
    void
    mark(int markLimit)
    Sets a mark position in this reader.
    boolean
    markSupported()
    Tests whether this reader supports the mark(int) and reset() methods.
    int
    peek()
    Returns the next character in the current reader without consuming it.
    int
    peek(char[] buf)
    Populates the buffer with the next buf.length characters in the current reader without consuming them.
    int
    read()
    Reads a single character from this reader and returns it with the two higher-order bytes set to 0.
    int
    read(char[] buffer, int offset, int length)
    Reads at most length characters from this reader and stores them at offset in the character array buffer.
    String
    readLine()
    Returns the next line of text available from this reader.
    boolean
    ready()
    Tests whether this reader is ready to be read without blocking.
    void
    reset()
    Resets this reader's position to the last mark() location.
    long
    skip(long amount)
    Skips amount characters in this reader.

    Methods inherited from class org.apache.commons.io.input.UnsynchronizedReader

    checkOpen, isClosed, setClosed

    Methods inherited from class java.io.Reader

    read, read

    Methods inherited from class java.lang.Object

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

  • Field Details

    • NUL

      private static final char NUL
      See Also:

    • in

      private final Reader in

    • buf

      private char[] buf
      The characters that can be read and refilled in bulk. We maintain three indices into this buffer: 
           { X X X X X X X X X X X X - - }
           ^     ^             ^
           |     |             |
         mark   pos           end

      Pos points to the next readable character. End is one greater than the last readable character. When pos == end, the buffer is empty and must be filled before characters can be read.

      Mark is the value pos will be set to on calls to reset(). Its value is in the range [0...pos]. If the mark is -1, the buffer cannot be reset.

      MarkLimit limits the distance between the mark and the pos. When this limit is exceeded, reset() is permitted (but not required) to throw an exception. For shorter distances, reset() shall not throw (unless the reader is closed).

    • pos

      private int pos

    • end

      private int end

    • mark

      private int mark

    • markLimit

      private int markLimit

  • Constructor Details

    • UnsynchronizedBufferedReader

      public UnsynchronizedBufferedReader(Reader in)
      Constructs a new BufferedReader on the Reader in. The buffer gets the default size (8 KB).
      Parameters:
      in - the Reader that is buffered.

    • UnsynchronizedBufferedReader

      public UnsynchronizedBufferedReader(Reader in, int size)
      Constructs a new BufferedReader on the Reader in. The buffer size is specified by the parameter size.
      Parameters:
      in - the Reader that is buffered.
      size - the size of the buffer to allocate.
      Throws:
      IllegalArgumentException - if size <= 0.

  • Method Details

    • chompNewline

      final void chompNewline() throws IOException
      Peeks at the next input character, refilling the buffer if necessary. If this character is a newline character ("\n"), it is discarded.
      Throws:
      IOException

    • close

      public void close() throws IOException
      Closes this reader. This implementation closes the buffered source reader and releases the buffer. Nothing is done if this reader has already been closed.
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Overrides:
      close in class UnsynchronizedReader
      Throws:
      IOException - if an error occurs while closing this reader.

    • fillBuf

      private int fillBuf() throws IOException
      Populates the buffer with data. It is an error to call this method when the buffer still contains data; ie. if pos < end.
      Returns:
      the number of bytes read into the buffer, or -1 if the end of the source stream has been reached.
      Throws:
      IOException

    • mark

      public void mark(int markLimit) throws IOException
      Sets a mark position in this reader. The parameter markLimit indicates how many characters can be read before the mark is invalidated. Calling reset() will reposition the reader back to the marked position if markLimit has not been surpassed.
      Overrides:
      mark in class Reader
      Parameters:
      markLimit - the number of characters that can be read before the mark is invalidated.
      Throws:
      IllegalArgumentException - if markLimit < 0.
      IOException - if an error occurs while setting a mark in this reader.
      See Also:

    • markSupported

      public boolean markSupported()
      Tests whether this reader supports the mark(int) and reset() methods. This implementation returns true.
      Overrides:
      markSupported in class Reader
      Returns:
      true for BufferedReader.
      See Also:

    • peek

      public int peek() throws IOException
      Returns the next character in the current reader without consuming it. So the next call to read() will still return this value.
      Returns:
      the next character
      Throws:
      IOException - If an I/O error occurs

    • peek

      public int peek(char[] buf) throws IOException
      Populates the buffer with the next buf.length characters in the current reader without consuming them. The next call to read() will still return the next value.
      Parameters:
      buf - the buffer to fill for the look ahead.
      Returns:
      the buffer itself
      Throws:
      IOException - If an I/O error occurs

    • read

      public int read() throws IOException
      Reads a single character from this reader and returns it with the two higher-order bytes set to 0. If possible, BufferedReader returns a character from the buffer. If there are no characters available in the buffer, it fills the buffer and then returns a character. It returns -1 if there are no more characters in the source reader.
      Overrides:
      read in class Reader
      Returns:
      the character read or -1 if the end of the source reader has been reached.
      Throws:
      IOException - if this reader is closed or some other I/O error occurs.

    • read

      public int read(char[] buffer, int offset, int length) throws IOException
      Reads at most length characters from this reader and stores them at offset in the character array buffer. Returns the number of characters actually read or -1 if the end of the source reader has been reached. If all the buffered characters have been used, a mark has not been set and the requested number of characters is larger than this readers buffer size, BufferedReader bypasses the buffer and simply places the results directly into buffer.
      Specified by:
      read in class Reader
      Parameters:
      buffer - the character array to store the characters read.
      offset - the initial position in buffer to store the bytes read from this reader.
      length - the maximum number of characters to read, must be non-negative.
      Returns:
      number of characters read or -1 if the end of the source reader has been reached.
      Throws:
      IndexOutOfBoundsException - if offset < 0 or length < 0, or if offset + length is greater than the size of buffer.
      IOException - if this reader is closed or some other I/O error occurs.

    • readLine

      public String readLine() throws IOException
      Returns the next line of text available from this reader. A line is represented by zero or more characters followed by LF, CR, "\r\n" or the end of the reader. The string does not include the newline sequence.
      Returns:
      the contents of the line or null if no characters were read before the end of the reader has been reached.
      Throws:
      IOException - if this reader is closed or some other I/O error occurs.

    • ready

      public boolean ready() throws IOException
      Tests whether this reader is ready to be read without blocking.
      Overrides:
      ready in class Reader
      Returns:
      true if this reader will not block when read is called, false if unknown or blocking will occur.
      Throws:
      IOException - if this reader is closed or some other I/O error occurs.
      See Also:

    • reset

      public void reset() throws IOException
      Resets this reader's position to the last mark() location. Invocations of read() and skip() will occur from this new location.
      Overrides:
      reset in class Reader
      Throws:
      IOException - if this reader is closed or no mark has been set.
      See Also:

    • skip

      public long skip(long amount) throws IOException
      Skips amount characters in this reader. Subsequent read()s will not return these characters unless reset() is used. Skipping characters may invalidate a mark if markLimit is surpassed.
      Overrides:
      skip in class UnsynchronizedReader
      Parameters:
      amount - the maximum number of characters to skip.
      Returns:
      the number of characters actually skipped.
      Throws:
      IllegalArgumentException - if amount < 0.
      IOException - if this reader is closed or some other I/O error occurs.
      See Also: