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