字符流：Writer/Reader(字符流)

通过子类FileWriter和FileReader实现父类实例化

package iotest;

import java.io.File;

import java.io.Writer;

import java.io.Reader;

import java.io.FileWriter;

import java.io.FileReader;

public class OutputStreamDemo2 {

public static void main(String args[]) throws Exception{

File f =new File("D:"+File.separator+"javasrc"+File.separator+"write_file.txt");

//写数据入文件

Writer w=new FileWriter(f);

String s="Jerry Wang!!";

w.write(s);

w.close();

//追加数据到文件

Writer w1=new FileWriter(f,true);

w1.write("\r\n");

w1.write(s);

w1.close();

//通过字符流读取文件

Reader r=new FileReader(f);

char c[]=new char[1024];

int len=r.read(c);

r.close();

print("the first read method:");

print(c,len);

//未知文件长度 读取文件

Reader r2=new FileReader(f);

char c2[]=new char[1024];

int temp=0;

int i=0;

    while((temp=r2.read())!=-1){

            c2[i]=(char)temp;

            i++;

    }

    r2.close();         

    print("the second read method:");

    print(c2,len);

}

public static void print(char b[],int len){

System.out.println(new String(b,0,len));

}

public static void print(char b[]){

System.out.println(new String(b));

}

public static void print(String b){

System.out.println(b);

}

}