如何在Windows7上使用NIO库更改Java中的文件权限

Question

我试图编写一段代码，以一个特定文件的路径对象开始，这样文件的所有者就不再有移动、删除或修改它的权限，但他们仍然可以读取它。还需要确保这可以撤消，并随时为管理员维护不受限制的访问权限

我的主要问题之一是，我不知道如何获取系统中的用户配置文件名和组名

一个深入的解释会很棒

Answer 1

File类可以设置文件的读取、写入和执行。要通过用户获取它，需要使用NIO

Files类和NIO使用PosixFilePermissions，它按文件和三个组（用户、所有者和组）设置权限。在Windows上，管理员和系统管理员将在一个组中

要移动它，我们需要我们自己的安全管理器。移动文件时，NIO使用写入权限。因此，我们的安全管理器必须修改写入权限。以下面的代码为例

另外，尽管文件系统提供程序是WindowsFileSystemProvider，但它是由FileSystemProviders返回的。getProvider（或类似的方法）。对于下载到的每个操作系统，rt.jar可能是不同的，但是如果你在Windows上，你可以假设这是正确的

路径限制器。java

package Testers;

import java.io.IOException;
import java.net.URI;
import java.nio.channels.SeekableByteChannel;
import java.nio.file.AccessMode;
import java.nio.file.CopyOption;
import java.nio.file.DirectoryStream;
import java.nio.file.DirectoryStream.Filter;
import java.nio.file.FileStore;
import java.nio.file.FileSystem;
import java.nio.file.Files;
import java.nio.file.LinkOption;
import java.nio.file.OpenOption;
import java.nio.file.Path;
import java.nio.file.attribute.BasicFileAttributes;
import java.nio.file.attribute.FileAttribute;
import java.nio.file.attribute.FileAttributeView;
import java.nio.file.attribute.PosixFilePermission;
import java.nio.file.spi.FileSystemProvider;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import sun.nio.fs.WindowsFileSystemProvider;


public class PathRestrictor extends FileSystemProvider{

    boolean canRead;
    boolean canWrite;
    boolean canMove; //This is the tricky one
    boolean canOpen;
    private Path path;
    WindowsFileSystemProvider provider = new WindowsFileSystemProvider();

    public PathRestrictor(Path p){
        path = p;
        canRead = true;
        canWrite = true;
        canOpen = true;
    }

    public void setExecuteable(boolean executable){
        canOpen = executable;
        try {
            Files.setPosixFilePermissions(path, getPerms());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void setReadable(boolean readable){
        canRead = readable;
        try {
            Files.setPosixFilePermissions(path, getPerms());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void setWriteable(boolean writeable){
        canWrite = writeable;
        try {
            Files.setPosixFilePermissions(path, getPerms());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void setMoveable(boolean moveable){
        canMove = moveable;
        MovementSecurityManager manager = new MovementSecurityManager();
        if(!moveable)manager.unMoveablePaths.add(path.toString());
        else manager.unMoveablePaths.remove(path.toString());
        System.setSecurityManager(manager);


    }

    private Set<PosixFilePermission> getPerms() {
        Set<PosixFilePermission> perms = new HashSet<PosixFilePermission>();
        perms.add(PosixFilePermission.GROUP_EXECUTE);
        perms.add(PosixFilePermission.GROUP_READ);
        perms.add(PosixFilePermission.GROUP_WRITE);
        if(canRead){
            perms.add(PosixFilePermission.OTHERS_READ);
            perms.add(PosixFilePermission.OWNER_READ);
        }
        if(canWrite){
            perms.add(PosixFilePermission.OTHERS_WRITE);
            perms.add(PosixFilePermission.OWNER_WRITE);
        }
        if(canOpen){
            perms.add(PosixFilePermission.OTHERS_EXECUTE);
            perms.add(PosixFilePermission.OWNER_EXECUTE);
        }
        return perms;
    }

    @Override
    public void checkAccess(Path path, AccessMode... modes) throws IOException {
        provider.checkAccess(path, modes);
    }

    @Override
    public void copy(Path source, Path target, CopyOption... options)
            throws IOException {
        // TODO Auto-generated method stub
        provider.copy(source, target, options);

    }

    @Override
    public void createDirectory(Path dir, FileAttribute<?>... attrs)
            throws IOException {
        provider.createDirectory(dir, attrs);
    }

    @Override
    public void delete(Path path) throws IOException {
        provider.delete(path);
    }

    @Override
    public <V extends FileAttributeView> V getFileAttributeView(Path path,
            java.lang.Class<V> type, LinkOption... options) {
        return provider.getFileAttributeView(path, type, options);
    }

    @Override
    public FileStore getFileStore(Path path) throws IOException {
        return provider.getFileStore(path);
    }

    @Override
    public FileSystem getFileSystem(URI uri) {
        return provider.getFileSystem(uri);
    }

    @Override
    public Path getPath(URI uri) {
        return provider.getPath(uri);
    }

    @Override
    public String getScheme() {
        return provider.getScheme();
    }

    @Override
    public boolean isHidden(Path path) throws IOException {
        return provider.isHidden(path);
    }

    @Override
    public boolean isSameFile(Path path, Path path2) throws IOException {
        return path.toString().equals(path2.toString());
    }

    @Override
    public void move(Path source, Path target, CopyOption... options)
            throws IOException {
            MovementSecurityManager manager = new MovementSecurityManager();
            manager.isMoving = true;
            System.setSecurityManager(manager);
            provider.move(source, target, options);
    }

    @Override
    public SeekableByteChannel newByteChannel(Path path,
            Set<? extends OpenOption> options, FileAttribute<?>... attrs)
            throws IOException {
        return provider.newByteChannel(path, options, attrs);
    }

    @Override
    public DirectoryStream<Path> newDirectoryStream(Path dir,
            Filter<? super Path> filter) throws IOException {
        return provider.newDirectoryStream(dir, filter);
    }

    @Override
    public FileSystem newFileSystem(URI uri, Map<String, ?> env)
            throws IOException {
        return provider.newFileSystem(uri, env);
    }

    @Override
    public <A extends BasicFileAttributes> A readAttributes(Path path,
            java.lang.Class<A> type, LinkOption... options) throws IOException {
        return provider.readAttributes(path, type, options);
    }

    @Override
    public Map<String, Object> readAttributes(Path path, String attributes,
            LinkOption... options) throws IOException {
        return provider.readAttributes(path, attributes, options);
    }

    @Override
    public void setAttribute(Path path, String attribute, Object value,
            LinkOption... options) throws IOException {
        provider.setAttribute(path, attribute, value, options);

    }

}

移动安全管理器。java

package Testers;

import java.util.HashSet;
import java.util.Set;

public class MovementSecurityManager extends SecurityManager {

    public Set<String> unMoveablePaths = new HashSet<String>();
    public boolean isMoving = true;

    public void checkWrite(String path){
        if(unMoveablePaths.contains(path) && isMoving) throw new SecurityException("Cannot move file!");
        else super.checkWrite(path);
    }

}