JAVA文件读写操作

package 实验;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

public class 文件读取 {
    public static void main(String[] args) throws IOException {
        FileInputStream fis = new FileInputStream("D:/file/123.txt");
        byte[] context = new byte[fis.available()];
        fis.read(context);

        String s = new String(context);
        System.out.println(s);
    }
}

package 实验;

import java.io.*;
import java.util.Scanner;

public class 文件写入 {
    public static void main(String[] args) throws IOException {
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入文本内容：");
        String context = sc.next();
        FileOutputStream fos = new FileOutputStream("D:/file/2.txt",true);  //不加true表示覆盖，加了表示追加
        fos.write(context.getBytes());
        fos.flush();
        fos.close();
    }
}

package 实验;

import java.io.FileInputStream;
import java.io.FileOutputStream;

public class 文件复制 {
    public static void main(String[] args) throws Exception{
        FileInputStream fis = new FileInputStream("D:/file/2.txt");
        byte[] context = new byte[fis.available()];
        fis.read(context);
        FileOutputStream fos =new FileOutputStream("D:/file/key/2.txt");
        fos.write(context);
        fos.flush();
        fos.close();
    }
}

package 实验;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class 日志生成代码 {
    public static void main(String[] args) throws Exception{
        try {
            FileInputStream fis = new FileInputStream("D:/file/3.txt");
        }catch (IOException e){
            FileOutputStream fos = new FileOutputStream("D:/file/log/log.txt",true);
            String date = new SimpleDateFormat("yyy-hh-dd HH:mm:ss").format(new Date());
            String log = date + " "+e.getMessage()+"\r\n";
            fos.write(log.getBytes());
            fos.flush();
            fos.close();
        }
    }
}