JAVA中File类的使用

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

public class Hello
{
    public static void main(String[] args) throws Exception
    {
        File f = new File("C:" + File.separator + "D" + File.separator + "code" + File.separator + "resource" + File.separator + "test.txt");
        if(f.exists())
        {
            f.delete();
        }
        else
        {
            f.createNewFile();
        }
    }
}

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

public class Hello
{
    public static void main(String[] args) throws Exception
    {
        File f = new File("C:" + File.separator + "D" + File.separator + "hello" + File.separator + "abc" + File.separator + "test.txt");
        String parentFolderPath = f.getParent();
        File parentFolder = f.getParentFile();
        System.out.println("文件的父路径是:" + parentFolderPath);
        if(!parentFolder.exists())
        {//创建文件的所有父文件夹
            System.out.println("该父路径不存在,现在为其创建一个。");
            parentFolder.mkdirs();
        }
        else
        {
            System.out.println("该父路径已经存在.");
        }
        
        if(f.exists())//判断文件是否存在
        {//若存在,则删除
            f.delete();
        }
        else
        {//若不存在,则创建
            f.createNewFile();
        }
    }
}

import java.util.*; 
import java.io.*;
import java.math.*;
import java.text.*;

public class Hello
{
    public static void main(String[] args) throws Exception
    {
        File f = new File("C:" + File.separator + "F"  + File.separator + "JAVA" + File.separator + "JavaWeb" + File.separator + "java_ee_javadocs.zip");
        long fileLength = f.length();
        long lastModifiedTime = f.lastModified();
        System.out.println("文件大小:" + new BigDecimal(fileLength).divide(new BigDecimal(1024*1024),2,RoundingMode.HALF_DOWN ) + "M");
        System.out.println("最后修改时间:" + new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SSS").format(lastModifiedTime));
        System.out.println("是否是文件:" + f.isFile());
        System.out.println("是否是文件夹:" + f.isDirectory());
    }
}

import java.util.*; 
import java.io.*;
import java.math.*;
import java.text.*;

public class Hello
{
    public static void main(String[] args) throws Exception
    {
        File f = new File("C:" + File.separator + "F"  + File.separator + "JAVA" + File.separator + "JavaWeb");
        if(f.isDirectory())
        {
            File[] files = f.listFiles();
            for(File item : files)
            {
                System.out.println(item.getName());
            }
            System.out.println("===================");
            String[] filesName = f.list();
            for(String item : filesName)
            {
                System.out.println(item);
            }
        } 
    }
}