java文件操作(一)

/*
 * file命令
 * exists()判断文件是否存在
 * delete()删除文件
 * makeDir()创建目录
 * isDirectory()判断目录是否存在
 * list()获取目录文件名列表
 * listFiles()获取目录文件路径列表
 */
package com.file;
import java.io.File;
import java.io.RandomAccessFile;
import java.util.RandomAccess;
public class file {
    public static void main(String args[]){
        File f = new File("D:"+File.separator+"t.txt");
        try {
            if(!f.exists()){
                if(f.createNewFile()){
                    System.out.println("创建文件成功！");
                }
            }else{
                System.out.println("文件已经存在！");
            }
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
          
        try {
            f = new File("D:"+File.separator+"t.txt");
            RandomAccessFile rac = new RandomAccessFile(f,"rw");
            byte bme[]=new byte[8];
            System.out.println(rac.read(bme));
              
        } catch (Exception e) {
            // TODO: handle exception
        }
          
            
        //delete("D:"+File.separator+"t.txt");
        //listFile2("D:"+File.separator);
           
        try {
            File f3 = new File("D:"+File.separator+"t.txt");
            RandomAccessFile raf = null;
            raf = new RandomAccessFile(f3, "rw");
            String name ="Xiao    ";
            int age = 30;
            raf.writeBytes(name);
            raf.writeInt(age);
              
            name ="Wang    ";
            age = 22;
            raf.writeBytes(name);
            raf.writeInt(age);
            raf.close();
              
               
            raf = new RandomAccessFile(f3, "rw");
            raf.skipBytes(12);
            //第二个人的信息
            byte b[]=new byte[8];
            for(int i=0;i<b.length;i++){
                b[i] = raf.readByte();
            }
            String str = new String(b);
            int ageshow = raf.readInt();
            System.out.println("姓名:"+str);
            System.out.println("年龄:"+age);
            raf.seek(0);
              
        } catch (Exception e) {
            // TODO: handle exception
        }
    }
    static void delete(String file){
        File f = new File(file);
        if(f.exists()){
            if(f.delete()){
                System.out.println("删除成功");
            }else{
                System.out.println("删除失败");
            }
        }else{
            System.out.println("文件不存在");
        }
        makeDir("D:"+File.separator+"dir");
        listFile2("D:"+File.separator);
    }
    static void makeDir(String dir){
        File f = new File(dir);
        if(f.isDirectory()){
            System.out.println("文件夹已经存在");
        }else{
            if(f.mkdir()){
                System.out.println("创建文件夹成功");
            }else{
                System.out.println("创建文件夹失败");
            }
        }
    }
    static void listFile(String path){
        File f = new File(path);
        String[]  list = f.list();
        for(int i=0;i<list.length;i++){
            System.out.println(list[i]);
        }
    }
    static void listFile2(String path){
        File f = new File(path);
        File f2 = null;
        File[] list = f.listFiles();
          
        for(int i=0;i<list.length;i++){
            f2 = list[i];
            if(f2.isDirectory()){
                System.out.println("\t 目录"+f2);
                listFile2(f2);
            }else{
                System.out.println(list[i]);
            }
        }
    }
    static void listFile2(File file){
        File f = file; 
        File[] list = f.listFiles();
        //判断文件列表是否为空(当遍历到System Volume Information目录时，没有权限访问，listFiles方法会返回null)
        if(list!=null){
            if(list.length>0  ){ 
                for(int i=0;i<list.length;i++){
                    System.out.println("\t\t"+list[i]);
                }
            }
        }  
    }
}