程序包 java.io

类 BufferedWriter

java.lang.Object

java.io.Writer

java.io.BufferedWriter

所有已实现的接口:

Closeable, Flushable, Appendable, AutoCloseable

public class BufferedWriter
extends Writer

Writes text to a character-output stream, buffering characters so as to provide for the efficient writing of single characters, arrays, and strings.

The buffer size may be specified, or the default size may be accepted. The default is large enough for most purposes.

A newLine() method is provided, which uses the platform's own notion of line separator as defined by the system property line.separator. Not all platforms use the newline character ('\n') to terminate lines. Calling this method to terminate each output line is therefore preferred to writing a newline character directly.

In general, a Writer sends its output immediately to the underlying character or byte stream. Unless prompt output is required, it is advisable to wrap a BufferedWriter around any Writer whose write() operations may be costly, such as FileWriters and OutputStreamWriters. For example,

 PrintWriter out
   = new PrintWriter(new BufferedWriter(new FileWriter("foo.out")));
 

will buffer the PrintWriter's output to the file. Without buffering, each invocation of a print() method would cause characters to be converted into bytes that would then be written immediately to the file, which can be very inefficient.

从以下版本开始:

JDK1.1

另请参阅:

PrintWriter, FileWriter, OutputStreamWriter, Files.newBufferedWriter(java.nio.file.Path, java.nio.charset.Charset, java.nio.file.OpenOption...)

字段概要

从类继承的字段 java.io.Writer

lock

构造器概要

构造器

构造器	说明
BufferedWriter(Writer out)	Creates a buffered character-output stream that uses a default-sized output buffer.
BufferedWriter(Writer out, int sz)	Creates a new buffered character-output stream that uses an output buffer of the given size.

方法概要

限定符和类型	方法	说明
void	close()	Closes the stream, flushing it first.
void	flush()	Flushes the stream.
void	newLine()	Writes a line separator.
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 s, int off, int len)	Writes a portion of a String.

从类继承的方法 java.lang.Object

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

从类继承的方法 java.io.Writer

append, append, append, write, write

构造器详细资料

BufferedWriter

public BufferedWriter(Writer out)

Creates a buffered character-output stream that uses a default-sized output buffer.

参数:

out - A Writer

BufferedWriter

public BufferedWriter(Writer out,
                      int sz)

Creates a new buffered character-output stream that uses an output buffer of the given size.

参数:

out - A Writer

sz - Output-buffer size, a positive integer

抛出:

IllegalArgumentException - If sz <= 0

方法详细资料

write

public void write(int c)
           throws IOException

Writes a single character.

覆盖:

write 在类中 Writer

参数:

c - int specifying a character to be written

抛出:

IOException - If an I/O error occurs

write

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

Writes a portion of an array of characters.

Ordinarily this method stores characters from the given array into this stream's buffer, flushing the buffer to the underlying stream as needed. If the requested length is at least as large as the buffer, however, then this method will flush the buffer and write the characters directly to the underlying stream. Thus redundant BufferedWriters will not copy data unnecessarily.

指定者:

write 在类中 Writer

参数:

cbuf - A character array

off - Offset from which to start reading characters

len - Number of characters to write

抛出:

IOException - If an I/O error occurs

write

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

Writes a portion of a String.

If the value of the len parameter is negative then no characters are written. This is contrary to the specification of this method in the superclass, which requires that an IndexOutOfBoundsException be thrown.

覆盖:

write 在类中 Writer

参数:

s - String to be written

off - Offset from which to start reading characters

len - Number of characters to be written

抛出:

IOException - If an I/O error occurs

newLine

public void newLine()
             throws IOException

Writes a line separator. The line separator string is defined by the system property line.separator, and is not necessarily a single newline ('\n') character.

抛出:

IOException - If an I/O error occurs

flush

public void flush()
           throws IOException

Flushes the stream.

指定者:

flush 在接口中 Flushable

指定者:

flush 在类中 Writer

抛出:

IOException - If an I/O error occurs

close

public void close()
           throws IOException

从类复制的说明: 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.

指定者:

close 在接口中 AutoCloseable

指定者:

close 在接口中 Closeable

指定者:

close 在类中 Writer

抛出:

IOException - If an I/O error occurs