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FilterReader (Java Platform SE 6) - JDK 5 Documentation v6.0, Java 2 SDK 英文文档

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java.io
Class FilterReader

java.lang.Object
  java.io.Reader
      java.io.FilterReader

All Implemented Interfaces:

Closeable, Readable

Direct Known Subclasses:

PushbackReader

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public abstract class FilterReader
extends Reader

Abstract class for reading filtered character streams. The abstract class FilterReader itself provides default methods that pass all requests to the contained stream. Subclasses of FilterReader should override some of these methods and may also provide additional methods and fields.

Since:

JDK1.1

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Field Summary
protected  Reader	in           The underlying character-input stream.

 

Fields inherited from class java.io.Reader
lock

 

Constructor Summary
protected	FilterReader(Reader in)           Creates a new filtered reader.

 

Method Summary
void	close()           Closes the stream and releases any system resources associated with it.
void	mark(int readAheadLimit)           Marks the present position in the stream.
boolean	markSupported()           Tells whether this stream supports the mark() operation.
int	read()           Reads a single character.
int	read(char[] cbuf, int off, int len)           Reads characters into a portion of an array.
boolean	ready()           Tells whether this stream is ready to be read.
void	reset()           Resets the stream.
long	skip(long n)           Skips characters.

 

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 Detail

in

protected Reader in

The underlying character-input stream.

Constructor Detail

FilterReader

protected FilterReader(Reader in)

Creates a new filtered reader.

Parameters:

in - a Reader object providing the underlying stream.

Throws:

NullPointerException - if in is null

Method Detail

read

public int read()
         throws IOException

Reads a single character.

Overrides:

read in class Reader

Returns:

The character read, as an integer in the range 0 to 65535 (0x00-0xffff), or -1 if the end of the stream has been reached

Throws:

IOException - If an I/O error occurs

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read

public int read(char[] cbuf,
                int off,
                int len)
         throws IOException

Reads characters into a portion of an array.

Specified by:

read in class Reader

Parameters:

cbuf - Destination buffer

off - Offset at which to start storing characters

len - Maximum number of characters to read

Returns:

The number of characters read, or -1 if the end of the stream has been reached

Throws:

IOException - If an I/O error occurs

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skip

public long skip(long n)
          throws IOException

Skips characters.

Overrides:

skip in class Reader

Parameters:

n - The number of characters to skip

Returns:

The number of characters actually skipped

Throws:

IOException - If an I/O error occurs

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ready

public boolean ready()
              throws IOException

Tells whether this stream is ready to be read.

Overrides:

ready in class Reader

Returns:

True if the next read() is guaranteed not to block for input, false otherwise. Note that returning false does not guarantee that the next read will block.

Throws:

IOException - If an I/O error occurs

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markSupported

public boolean markSupported()

Tells whether this stream supports the mark() operation.

Overrides:

markSupported in class Reader

Returns:

true if and only if this stream supports the mark operation.

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mark

public void mark(int readAheadLimit)
          throws IOException

Marks the present position in the stream.

Overrides:

mark in class Reader

Parameters:

readAheadLimit - Limit on the number of characters that may be read while still preserving the mark. After reading this many characters, attempting to reset the stream may fail.

Throws:

IOException - If an I/O error occurs

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reset

public void reset()
           throws IOException

Resets the stream.

Overrides:

reset in class Reader

Throws:

IOException - If an I/O error occurs

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close

public void close()
           throws IOException

Description copied from class: Reader

Closes the stream and releases any system resources associated with it. Once the stream has been closed, further read(), ready(), mark(), reset(), or skip() invocations will throw an IOException. Closing a previously closed stream has no effect.

Specified by:

close in interface Closeable

Specified by:

close in class Reader

Throws:

IOException - If an I/O error occurs

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For further API reference and developer documentation, see Java SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

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