java --NIO and Interfaces

操作文件和目录

1.建立文件或目录

import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.FileAttribute;
import java.nio.file.attribute.PosixFilePermission;
import java.nio.file.attribute.PosixFilePermissions;
import java.util.Set;

public class FileDemo {
    public static void main(String args[]) {
        Path p=Paths.get("G:\学习型文档\java_test\Myfile.txt");
        //创建泛型集合
    //Set<PosixFilePermission> perms=PosixFilePermissions.fromString("rw-rw-rw-");
    //ileAttribute <Set<PosixFilePermission>> attr=PosixFilePermissions.asFileAttribute(perms);
        
        try {
            Files.createFile(p);    
        }
        catch(Exception e) {
            System.out.println("文件已经存在！");
        }
        
        
    }
}

 测试结果：

2.复制文件或目录

 在1的基础上执行：

import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.FileAttribute;
import java.nio.file.attribute.PosixFilePermission;
import java.nio.file.attribute.PosixFilePermissions;
import java.util.Set;

public class FileDemo {
    public static void main(String args[]) {
        Path p=Paths.get("G:\学习型文档\java_test\Myfile.txt");
        Path PP=Paths.get("G:\学习型文档\java_test\Myfile1.txt");
        //创建泛型集合
    //Set<PosixFilePermission> perms=PosixFilePermissions.fromString("rw-rw-rw-");
    //ileAttribute <Set<PosixFilePermission>> attr=PosixFilePermissions.asFileAttribute(perms);
        
        try {
            Files.copy(p,PP);    
        }
        catch(Exception e) {
            System.out.println("文件已经存在！");
        }
        
        
    }
}

测试结果：

3.移动文件或目录;

import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.FileAttribute;
import java.nio.file.attribute.PosixFilePermission;
import java.nio.file.attribute.PosixFilePermissions;
import java.util.Set;

public class FileDemo {
    public static void main(String args[]) {
        Path p=Paths.get("G:\学习型文档\java_test\Myfile.txt");
        Path PP=Paths.get("G:\学习型文档\java_test\Myfile1.txt");
        Path PPP=Paths.get("G:\学习型文档\java_test\Myfile2.txt");
        //创建泛型集合
    //Set<PosixFilePermission> perms=PosixFilePermissions.fromString("rw-rw-rw-");
    //ileAttribute <Set<PosixFilePermission>> attr=PosixFilePermissions.asFileAttribute(perms);
        
        try {
            Files.move(p,PPP);    
        }
        catch(Exception e) {
            System.out.println("文件已经存在！");
        }
        
        
    }
}

测试结果：

4.遍历文件树：

import java.io.IOException;
import java.nio.file.FileVisitResult;
import java.nio.file.FileVisitor;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.BasicFileAttributes;

class MyFileVisitor implements FileVisitor<Path> {

    public FileVisitResult postVisitDirectory(Path dir, IOException e) throws IOException {
        System.out.println("Just Visited" + dir);
        return FileVisitResult.CONTINUE;
    }

    public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException {
        System.out.println("About to visit" + dir);
        return FileVisitResult.CONTINUE;
    }

    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
        System.out.println("Currently visiting " + file);
        System.out.println("Is this file a  directory:" + Files.isDirectory(file));
        System.out.println("Checking done...!!");
        return FileVisitResult.CONTINUE;
    }

    public FileVisitResult visitFileFailed(Path file, IOException e) throws IOException {
        System.err.println(e.getMessage());
        return FileVisitResult.CONTINUE;
    }
}

public class NIODemo {
    public static void main(String args[]) throws IOException {
        Path listDir = Paths.get("G:\学习型文档\C_矩阵");
        MyFileVisitor obj = new MyFileVisitor();
        Files.walkFileTree(listDir, obj);

    }
}

此代码为遍历 G:\学习型文档\C_矩阵 该文件下的文件树：
测试结果：

实现监视服务：