Java 轻松入门了解File类的使用

import java.io.File;

public class FileDemo1 {

     public static void main(String[] args) {

         //public File(String pathname)

         String pathname1 = "F:\\test1.txt" ;

         File file1 = new File(pathname1);

         //public File(String pathname)

         String pathname2 = "F:\\test2\\test1.txt" ;

         File file2 = new File(pathname2);

         //下面用的少

         //public File(String parent, String child)

         String parent = "F:\\test3" ;

         String child = "test1.txt" ;

         File file3 = new File(parent,child);

         //public File(File parent, String child)

         File parentDir = new File( "F:\\test" );

         String child1 = "test2.txt" ;

         File file4 = new File(parentDir,child1);

     }

}

import java.io.File;

public class FileDemo2 {

     public static void main(String[] args) {

         File file = new File( "F:\\test1\\test2\\text.txt" );

         //将此File转换为路径名字符串。

         System.out.println( "文件路径：" + file.getPath());

         //返回由此File表示的文件或目录的名称

         System.out.println( "文件名称：" + file.getName());

         //获得父级路径

         System.out.println( "获得父级路径" + file.getParent());

         //返回此File的绝对路径名字符串

         System.out.println( "绝对路径名称" + file.getAbsolutePath());

     }

}

import java.io.File;

public class FileDemo3 {

     public static void main(String[] args) {

         File file1 = new File( "F:\\test\\test1\\test2.txt" );

         File file2 = new File( "F:\\test" );

         //此File表示的文件或目录是否实际存在

         boolean exists1 = file1.exists();

         boolean exists2 = file2.exists();

         System.out.println(exists1);

         System.out.println(exists2);

         //此File表示的是否为目录

         boolean directory1 = file1.isDirectory();

         boolean directory2 = file2.isDirectory();

         System.out.println(directory1);

         System.out.println(directory2);

         //此File表示的是否为文件

         boolean file1File = file1.isFile();

         boolean file2File = file2.isFile();

         System.out.println(file1File);

         System.out.println(file2File);

         //判断File对象对应的文件或目录是否是绝对路径

         boolean absolute = file1.isAbsolute();

         System.out.println(absolute);

         //判断File对象对应的文件或目录是否可读

         boolean canRead = file1.canRead();

         System.out.println(canRead);

         //判断File对象对应的文件或目录是否可写

         boolean canWrite = file1.canWrite();

         System.out.println(canWrite);

         //判断File对象对应的文件或目录是否是否隐藏

         boolean hidden = file2.isHidden();

         System.out.println(hidden);

     }

}

import java.io.File;

import java.io.IOException;

public class FileDemo4 {

     public static void main(String[] args) throws IOException {

         //创建文件

         File file1 = new File( "test.txt" );

         System.out.println( "是否存在:" + file1.exists()); //false

         System.out.println( "是否创建" + file1.createNewFile()); //需要抛出异常

         System.out.println( "是否存在：" + file1.exists()); //true

         //创建目录(单个)

         File file2 = new File( "F:\\test" );

         System.out.println( "是否存在:" + file2.exists()); //false

         System.out.println( "是否创建" + file2.mkdir());

         System.out.println( "是否存在：" + file2.exists()); //true

         //创建多级目录

         File file3 = new File( "F:\\test1\\test2" );

         System.out.println( "是否存在:" + file3.exists()); //false

         System.out.println( "是否创建" + file3.mkdirs());

         System.out.println( "是否存在：" + file3.exists()); //true

         //文件的删除

         System.out.println(file1.delete());

         //目录的删除

         System.out.println(file2.delete());

         System.out.println(file3.delete()); //只能删除一级

     }

}

import org.junit.Test;

import java.io.File;

import java.io.IOException;

public class FileDemo5 {

     public static void main(String[] args) {

         File dir = new File( "F:\\test" );

         dir.mkdirs();

         System.out.println(dir.exists());

         //File dir1 = new File("F:\\test");

         //获取当前目录下的文件及文件夹的名称

         String[] names = dir.list();

         //遍历

         for (String name : names){

             System.out.println(name);

         }

         //获取当前目录下的文件以及文件夹对象，只要拿到了文件对象，那么就可以获取更多信息

         File[] files = dir.listFiles();

         for (File file : files){

             System.out.println(file);

         }

     }

}

/*

多级目录的打印。遍历之前，无从知道到底有多少级目录，所以我们可以使用递归实现

  */

import java.io.File;

public class FileDemo6 {

     public static void main(String[] args) {

         File dir = new File( "F:\\test1" );

         listSubFiles(dir);

     }

     private static void listSubFiles(File dir) {

         if (dir != null && dir.isDirectory()){

             File[] listFiles = dir.listFiles();

             if (dir != null ){

                 for (File sub : listFiles){

                     listSubFiles(sub); //递归调用

                 }

             }

         }

         System.out.println(dir);

     }

}