案例

读取文件

import java.io.*;
public class Main {
    public static void main(String[] args) throws Exception {
        String path = "./story.txt";
        boolean append = true;
        BufferedWriter bw = new BufferedWriter(new FileWriter(path, append));
        bw.write("123\n");
        bw.write(97);
        bw.newLine();
        bw.write(new char[]{'G', 'G', 'C', '\n'});
        bw.write("123\n56789", 0, 9);
        bw.write(new char[]{'G', 'G', 'C', 'S', '\n'}, 0, 5);
        bw.close();
    }
}

复制文件

一边读一边写

import java.io.*;
public class Main {
    public static void main(String[] args) throws Exception {
        String srcPath = "./story.txt";
        String copypath = "./story_copy.txt";
        boolean append = false;
        BufferedReader br = new BufferedReader(new FileReader(srcPath));
        BufferedWriter bw = new BufferedWriter(new FileWriter(copypath, append));
        String line;
        while ((line = br.readLine()) != null) {
            bw.write(line);
            bw.newLine();
        }
        br.close();
        bw.close();
    }
}