BufferedWrite中：用void newLine（）写一行行分隔符，分隔符由系统属性定义

BuffereReader：public String readLine（）：读一行文字，结果包含的内容的字符串，如果流的结尾已经到达，则为null

package day4;
​
import java.io.*;
​
public class WriteReadTest {
    public static void main(String[] args) throws IOException {
        FileWriter fw = new FileWriter("write.txt");
        BufferedWriter bw = new BufferedWriter(fw);
        for (int i = 0; i < 5; i++) {
            bw.write("hello");
            bw.newLine();
        }
        bw.flush();
        FileReader fr = new FileReader("write.txt");
        BufferedReader br = new BufferedReader(fr);
        String s;
        while ((s=br.readLine())!=null){
            System.out.println(s);
        }
        br.close();
        fr.close();
        bw.close();
        fw.close();
    }
}
​

用字符缓冲流复制文件

package day4;

import java.io.*;

public class WriteReadTest {
    public static void main(String[] args) throws IOException {
        FileWriter fw = new FileWriter("write2.txt");
        BufferedWriter bw = new BufferedWriter(fw);
        FileReader fr = new FileReader("write.txt");
        BufferedReader br = new BufferedReader(fr);
        String s;
        while ((s=br.readLine())!=null){
            bw.write(s);
            bw.newLine();
        }
        br.close();
        fr.close();
        bw.close();
        fw.close();
    }
}