字符流

字符输入流Reader

import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

public class Demo04 {
    public static void main(String[] args) throws IOException {
        method1();
        method2();
        method3();
        copy();
    }
FileReader类

//文本文件建议用字符流读取
    public static void method1() throws IOException{
        //创建字符输入流
        FileReader fr=new FileReader("E:\java\demo.txt");
        int len=0;
        while((len=fr.read())!=-1){
            System.out.println((char)len);
        }
        fr.close();
    }
    public static void method2() throws IOException{
        FileReader fr=new FileReader("E:\java\demo.txt");
        char[] ch=new char[2];
        int len=0;
        while((len=fr.read(ch))!=-1){
            System.out.println(new String(ch,0,len));//解码
        }
        fr.close();
    }
字符输出流Writer

FileWriter类
构造方法

//往文件里写
    public static void method3() throws IOException{
        FileWriter fw=new FileWriter("E:\java\demo.txt",true);
        fw.write(100);
        fw.flush();//刷一下
        char[] ch={'a','中'};
        fw.write(ch);
        fw.flush();
        fw.write("你好，小猪佩奇");
        fw.close();
    }
flush()和close()的区别？

复制文本文件
    //复制文本文件
    public static void copy() throws IOException{
        //明确数据源
        FileReader fr=new FileReader("E:\java\demo.txt");
        //明确目的文件
        FileWriter fw=new FileWriter("E:\java\c.txt");
        int len=0;
        char[] ch=new char[2];
        while((len=fr.read(ch))!=-1){
            fw.write(ch, 0, len);
            fw.flush();
        }
        fr.close();
        fw.close();
    }
}