Files 类使用

package com.xinyu.test;

import java.io.IOException;

import java.nio.ByteBuffer;

import java.nio.channels.FileChannel;

import java.nio.charset.StandardCharsets;

import java.nio.file.Files;

import java.nio.file.LinkOption;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.nio.file.StandardCopyOption;

import java.nio.file.StandardOpenOption;

import java.util.List;

public class FileTest {

    public static void main(String[] args) {

        // TODO Auto-generated method stub

        //Files创建，删除

//      Path path =Paths.get("D:/jun/xinyu.txt");

//      try {

//          Files.createFile(path);

//          Files.deleteIfExists(path);

//      } catch (IOException e) {

//          // TODO Auto-generated catch block

//          e.printStackTrace();

//      }

        //Files复制，移动

//      try {

//          Path path = Paths.get("D:/jun/psb (4).jpg");

//          Path target =Paths.get("D:/test/jun.jpg");

//          Path parent = target.getParent();

//          boolean exists = parent.toFile().exists();

//          if(!exists){

//              Files.createDirectories(parent);

//          }

////            Files.copy(path, target, StandardCopyOption.REPLACE_EXISTING);

//          Files.move(path, target, StandardCopyOption.REPLACE_EXISTING);

//

//      } catch (IOException e) {

//          // TODO Auto-generated catch block

//          e.printStackTrace();

//      }

        //查看文件属性

//      Path path = Paths.get("D:/liebao/debug.log");

//      try {

//          System.out.println(Files.getLastModifiedTime(path));

//          System.out.println(Files.size(path));

//          System.out.println(Files.isDirectory(path));

//          System.out.println(Files.readAttributes(path, "*"));

//          System.out.println();

//          System.out.println();

//          System.out.println(19_12);

//      } catch (IOException e) {

//          // TODO Auto-generated catch block

//          e.printStackTrace();

//      }

        //简化的文件读写

//      Path path =Paths.get("D:/liebao/debug.log");

//      try {

//          List<String> readAllLines = Files.readAllLines(path,StandardCharsets.UTF_8);

//          for (String entry : readAllLines){

//              System.out.println(entry);

//          }

//

//          byte[] readAllBytes = Files.readAllBytes(path);

//          System.out.println(new String(readAllBytes));

//

//      } catch (IOException e) {

//          // TODO Auto-generated catch block

//          e.printStackTrace();

//      }

        //读取文件的最后几个字节

        Path path=Paths.get("D:/liebao/test.txt");

        try {

            FileChannel open = FileChannel.open(path, StandardOpenOption.READ);

            ByteBuffer buffer = ByteBuffer.allocate(1024);

            //从第23个字节开始读

//          int read = open.read(buffer,open.size()-(open.size()-23));/

//          open.read(buffer, 2, 10);

//          System.out.println(new String(buffer.array()));

//          System.out.println(open.size());

            //下面的一直报错，不管了先

            ByteBuffer[] dsts = new ByteBuffer[12];

            System.out.println(dsts.length);

            System.out.println(open == null);

            open.read(dsts, 1, 3);

            System.out.println(dsts[0].array());

        } catch (IOException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }

    }

}

Paths类的使用：

package com.xinyu.test;

import java.io.File;

import java.io.IOException;

import java.nio.file.DirectoryStream;

import java.nio.file.FileVisitResult;

import java.nio.file.Files;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.nio.file.SimpleFileVisitor;

import java.nio.file.attribute.BasicFileAttributes;

public class PathTest {

    public static void main(String[] args) {

        // TODO Auto-generated method stub

        //Path  基本操作

//      Path path = Paths.get("D:/jun");

//      System.out.println(path.getFileName());

//      System.out.println(path.getFileSystem());

//      System.out.println(path.getNameCount());

//      System.out.println(path.getParent());

        //path 的合并

//      Path path = Paths.get("D:/");

//      Path resolve = path.resolve("jun");

//      System.out.println(resolve.getFileName());

//      System.out.println(resolve.getFileSystem());

//      System.out.println(resolve.getNameCount());

//      System.out.println(resolve.getParent());

        //从path到path2的相对路径，输出：..\cebdoc

//      Path path = Paths.get("D:/jun");

//      Path path2 = Paths.get("D:/cebdoc");

//      Path relativize = path.relativize(path2);

//      System.out.println(relativize);

        //path的一些其他操作，包括startWith,endWith

//      Path path = Paths.get("D:/jun");

//      Path path2 = Paths.get("D:/cebdoc");

//      boolean startsWith = path.startsWith(path2);

//      System.out.println(startsWith);

        //jdk1.7之后 path 和file是可以相互转换的

//      File file = new File("D:/jun");

//      Path path3 = file.toPath();

//      file =path3.toFile();

        //path遍历目录  只输出制定的文件  列出目录下的所有txt文件

//      Path path = Paths.get("D:\\jun");

//      try {

//          DirectoryStream<Path> stream = Files.newDirectoryStream(path,"*.txt");

//          for (Path entry : stream){

//              System.out.println(entry.getFileName());

//          }

//      } catch (IOException e) {

//          // TODO Auto-generated catch block

//          e.printStackTrace();

//      }

        //path遍历目录，以及目录下的目录  找出是所有的doc文件

        class FindJavaVisitor extends SimpleFileVisitor<Path>{

            @Override

            public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {

                // TODO Auto-generated method stub

                if(file.toString().endsWith(".txt")){

                    System.out.println(file.getFileName());

                }

                return super.visitFile(file, attrs);

            }

        }

        Path path = Paths.get("D:\\software");

        try {

            Files.walkFileTree(path, new FindJavaVisitor());

        } catch (IOException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }

    }

}

文件观察服务的使用

WatchService

package com.xinyu.test;

import java.io.IOException;

import java.nio.file.FileSystem;

import java.nio.file.FileSystems;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.nio.file.StandardWatchEventKinds;

import java.nio.file.WatchEvent;

import java.nio.file.WatchKey;

import java.nio.file.WatchService;

public class FilWatchServicesTest {

    public static void main(String[] args) {

        try {

            WatchService watchService = FileSystems.getDefault().newWatchService();

            Path path =Paths.get("D:/jun");

            path.register(watchService,StandardWatchEventKinds.ENTRY_MODIFY);

            while (true) {

                WatchKey take = watchService.take();

                for (WatchEvent<?> event : take.pollEvents()) {

                    if (event.kind() == StandardWatchEventKinds.ENTRY_DELETE) {

                        System.out.println("i is delete");

                    }

                    if (event.kind() == StandardWatchEventKinds.ENTRY_MODIFY) {

                        System.out.println("i is modify");

                    }

                }

                take.reset();

            }

        } catch (IOException | InterruptedException e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }

    }

}