Java IO流笔记

默默赞一下老师超好用的PPT

File 类

ps:注意file的delete失败可能是输入输出流还在用这个file

Java实现简单文件管理

package fileDemo;

import java.io.File;
import java.util.Scanner;

public class DirExp {

    public static boolean isDirectory(String path) {
        File file = new File(path);
        return file.isDirectory();
    }
    
    public static boolean isExists(String path) {
        File file = new File(path);
        return file.exists();
    }
    
    public static String [] getSubFiles(String path) {
        File file = new File(path);
        return file.list();
    }
    
    
    public static void main(String[] args) {
        Scanner cin = new Scanner(System.in);
        String path = "";
        path = cin.nextLine();
        if(!DirExp.isDirectory(path)) {
            System.out.println("It's not a directory.");
            return ;
        } 
        if(!DirExp.isExists(path)) {
            System.out.println("It's not existe.");
            return ;
        }
        String []subFiles = DirExp.getSubFiles(path);
        for(String s: subFiles) {
            System.out.println(s);
        }
        cin.close();
    }

}

FileInputStream 和 FileOutputStream

 

java实现粘贴文件和剪切文件的功能

package fileDemo;

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

public class FileOperation {

    public static int copyFile(String path1, String path2) throws IOException {

        File file1 = new File(path1);
        File file2 = new File(path2);
        if(!file1.isFile()) {
            return -1;
        }
        if(!file1.exists()) {
            return -2;
        }
        

        FileInputStream inputStream = new FileInputStream(file1);
        FileOutputStream outputStream = new FileOutputStream(file2);
 
        byte data[] = new byte[(int)file1.length()];
        inputStream.read(data);
        for(byte a: data) {
            System.out.print((char)a);
            outputStream.write((int)a);
        }
        System.out.println();
        outputStream.close();
        inputStream.close();
        return 1;
    }
    
    public static int cutFile(String path1, String path2) throws IOException {
        int ret = copyFile(path1, path2);
        if(ret < 0) {
            return -1;
        }
        File file = new File(path1);
        file.delete();
        return 1;
    }
    
    public static void main(String[] args) throws IOException {
        //copyFile("D:\tmp\test.txt", "D:\tmp\test3.txt");
        cutFile("D:\tmp\test2.txt", "D:\tmp\test3.txt");
    }

}

简单来说: File类针对文件，文件流类使用File的对象创建实例。然后调用read或者write，最后关闭。注意关闭流的顺序