Java I/O 教程（八） Writer和Reader

Java Writer

Writer是一个用于写字符流的抽象类。其子类必须实现write(char[], int, int), flush(), 和 close()方法。

类定义

public abstract class Writer
extends Object
implements Appendable, Closeable, Flushable

属性

Modifier and Type    Field    Description
protected Object    lock    The object used to synchronize operations on this stream.

构造函数

protected    Writer()
Creates a new character-stream writer whose critical sections will synchronize on the writer itself.

常用方法

Writer        append(char c)                                    往writer追加指定字符
Writer        append(CharSequence csq)                        追加指定字符序列
Writer        append(CharSequence csq, int start, int end)    追加指定字符序列的子序列
abstract     void    close()                                    先冲刷后关闭流
abstract     void    flush()                                    冲刷流
void        write(char[] cbuf)                                写字符数组
abstract     void    write(char[] cbuf, int off, int len)    写字符数组的部分
void        write(int c)                                    写单个字符
void        write(String str)                                写字符串

void        write(String str, int off, int len)                写部分字符串

例子

package com.dylan.io;

import java.io.FileWriter;
import java.io.IOException;
import java.io.Writer;

/**
 * @author xusucheng
 * @create 2018-01-07
 **/
public class WriterExample {
    public static void main(String[] args) throws IOException {
        Writer w = new FileWriter("D:\\output.txt");
        String content = "I love my country.";
        w.write(content);
        w.close();
        System.out.println("Done.");
    }
}

Java Reader

Reader 是一个用于读取字符流的抽象类。其子类必须实现的方法只有：read(char[], int, int) 和 close()。

实现类包括： BufferedReader, CharArrayReader, FilterReader, InputStreamReader, PipedReader, StringReader

类定义

public abstract class Reader
extends Object
implements Readable, Closeable

属性

protected Object

lock The object used to synchronize operations on this stream.

构造函数

protected	Reader() Creates a new character-stream reader whose critical sections will synchronize on the reader itself.
protected	Reader(Object lock) Creates a new character-stream reader whose critical sections will synchronize on the given object.

常用方法

abstract 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) Reads characters into an array.
abstract int	read(char[] cbuf, int off, int len) Reads characters into a portion of an array.
int	read(CharBuffer target) Attempts to read characters into the specified character buffer.
boolean	ready() Tells whether this stream is ready to be read.
void	reset() Resets the stream.
long	skip(long n) Skips characters.

例子

package com.dylan.io;

import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;

/**
 * @author xusucheng
 * @create 2018-01-07
 **/
public class ReaderExample {
    public static void main(String[] args) throws IOException{
        Reader r = new FileReader("D:\\output.txt");
        int data = 0;
        while ((data=r.read())!=-1){
            System.out.print((char)data);
        }

        r.close();
    }
}

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