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

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java.io
Class OutputStreamWriter

java.lang.Object
  java.io.Writer
      java.io.OutputStreamWriter

All Implemented Interfaces:

Closeable, Flushable, Appendable

Direct Known Subclasses:

FileWriter

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public class OutputStreamWriter
extends Writer

An OutputStreamWriter is a bridge from character streams to byte streams: Characters written to it are encoded into bytes using a specified charset. The charset that it uses may be specified by name or may be given explicitly, or the platform's default charset may be accepted.

Each invocation of a write() method causes the encoding converter to be invoked on the given character(s). The resulting bytes are accumulated in a buffer before being written to the underlying output stream. The size of this buffer may be specified, but by default it is large enough for most purposes. Note that the characters passed to the write() methods are not buffered.

For top efficiency, consider wrapping an OutputStreamWriter within a BufferedWriter so as to avoid frequent converter invocations. For example:

 Writer out
   = new BufferedWriter(new OutputStreamWriter(System.out));
 

A surrogate pair is a character represented by a sequence of two char values: A high surrogate in the range '\uD800' to '\uDBFF' followed by a low surrogate in the range '\uDC00' to '\uDFFF'.

A malformed surrogate element is a high surrogate that is not followed by a low surrogate or a low surrogate that is not preceded by a high surrogate.

This class always replaces malformed surrogate elements and unmappable character sequences with the charset's default substitution sequence. The CharsetEncoder class should be used when more control over the encoding process is required.

Since:

JDK1.1

See Also:

BufferedWriter, OutputStream, Charset

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Field Summary

 

Fields inherited from class java.io.Writer
lock

 

Constructor Summary
OutputStreamWriter(OutputStream out)           Creates an OutputStreamWriter that uses the default character encoding.
OutputStreamWriter(OutputStream out, Charset cs)           Creates an OutputStreamWriter that uses the given charset.
OutputStreamWriter(OutputStream out, CharsetEncoder enc)           Creates an OutputStreamWriter that uses the given charset encoder.
OutputStreamWriter(OutputStream out, String charsetName)           Creates an OutputStreamWriter that uses the named charset.

 

Method Summary
void	close()           Closes the stream, flushing it first.
void	flush()           Flushes the stream.
String	getEncoding()           Returns the name of the character encoding being used by this stream.
void	write(char[] cbuf, int off, int len)           Writes a portion of an array of characters.
void	write(int c)           Writes a single character.
void	write(String str, int off, int len)           Writes a portion of a string.

 

Methods inherited from class java.io.Writer
append, append, append, write, write

 

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

 

Constructor Detail

OutputStreamWriter

public OutputStreamWriter(OutputStream out,
                          String charsetName)
                   throws UnsupportedEncodingException

Creates an OutputStreamWriter that uses the named charset.

Parameters:

out - An OutputStream

charsetName - The name of a supported charset

Throws:

UnsupportedEncodingException - If the named encoding is not supported

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OutputStreamWriter

public OutputStreamWriter(OutputStream out)

Creates an OutputStreamWriter that uses the default character encoding.

Parameters:

out - An OutputStream

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OutputStreamWriter

public OutputStreamWriter(OutputStream out,
                          Charset cs)

Creates an OutputStreamWriter that uses the given charset.

Parameters:

out - An OutputStream

cs - A charset

Since:

1.4

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OutputStreamWriter

public OutputStreamWriter(OutputStream out,
                          CharsetEncoder enc)

Creates an OutputStreamWriter that uses the given charset encoder.

Parameters:

out - An OutputStream

enc - A charset encoder

Since:

1.4

Method Detail

getEncoding

public String getEncoding()

Returns the name of the character encoding being used by this stream.

If the encoding has an historical name then that name is returned; otherwise the encoding's canonical name is returned.

If this instance was created with the OutputStreamWriter(OutputStream, String) constructor then the returned name, being unique for the encoding, may differ from the name passed to the constructor. This method may return null if the stream has been closed.

Returns:

The historical name of this encoding, or possibly null if the stream has been closed

See Also:

Charset

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write

public void write(int c)
           throws IOException

Writes a single character.

Overrides:

write in class Writer

Parameters:

c - int specifying a character to be written

Throws:

IOException - If an I/O error occurs

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write

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

Writes a portion of an array of characters.

Specified by:

write in class Writer

Parameters:

cbuf - Buffer of characters

off - Offset from which to start writing characters

len - Number of characters to write

Throws:

IOException - If an I/O error occurs

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write

public void write(String str,
                  int off,
                  int len)
           throws IOException

Writes a portion of a string.

Overrides:

write in class Writer

Parameters:

str - A String

off - Offset from which to start writing characters

len - Number of characters to write

Throws:

IOException - If an I/O error occurs

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flush

public void flush()
           throws IOException

Flushes the stream.

Specified by:

flush in interface Flushable

Specified by:

flush in class Writer

Throws:

IOException - If an I/O error occurs

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close

public void close()
           throws IOException

Description copied from class: Writer

Closes the stream, flushing it first. Once the stream has been closed, further write() or flush() invocations will cause an IOException to be thrown. Closing a previously closed stream has no effect.

Specified by:

close in interface Closeable

Specified by:

close in class Writer

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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