java修改文件所有者及其權限

1.設置所有者

管理文件所有者

Files.getOwner()和Files.setOwner()方法

要使用UserPrincipal來管理文件的所有者

（1）更改文件的所有者

import java.io.IOException;
import java.nio.file.*;
import java.nio.file.attribute.FileOwnerAttributeView;
import java.nio.file.attribute.UserPrincipal;
import java.nio.file.attribute.UserPrincipalLookupService;

public class Main {
    public static void main(String[] args) {

        Path path = Paths.get("/www/test1.txt");

        FileOwnerAttributeView foav = Files.getFileAttributeView(path,
                FileOwnerAttributeView.class);
        try {
            UserPrincipal owner = foav.getOwner();
            System.out.format("Original owner  of  %s  is %s%n", path,
                    owner.getName());

            FileSystem fs = FileSystems.getDefault();
            UserPrincipalLookupService upls = fs.getUserPrincipalLookupService();

            UserPrincipal newOwner = upls.lookupPrincipalByName("abc");
            foav.setOwner(newOwner);

            UserPrincipal changedOwner = foav.getOwner();
            System.out.format("New owner  of  %s  is %s%n", path,
                    changedOwner.getName());

        }catch (IOException e){
            e.printStackTrace();
        }

    }
}

輸出

查看文件詳細信息

2.ACL文件權限

Windows上支持ACL類型文件屬性

使用AclFileAttributeView的

　　getAcl()方法獲取文件的AclEntry列表

　　setAcl()方法設置文件的AclEntry列表

（1）讀取文件e:/test1.txt的ACL條目

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.AclEntry;
import java.nio.file.attribute.AclEntryPermission;
import java.nio.file.attribute.AclFileAttributeView;
import java.util.List;
import java.util.Set;

public class Main {
    public static void main(String[] args) {
       
        Path path = Paths.get("e:/test1.txt");
        AclFileAttributeView aclView = Files.getFileAttributeView(path,
                AclFileAttributeView.class);
        if (aclView == null) {
            System.out.format("ACL view  is not  supported.%n");
            return;
        }
        try {
            List<AclEntry> aclEntries = aclView.getAcl();
            for (AclEntry entry : aclEntries) {
                System.out.format("Principal: %s%n", entry.principal());
                System.out.format("Type: %s%n", entry.type());
                System.out.format("Permissions are:%n");

                Set<AclEntryPermission> permissions = entry.permissions();
                for (AclEntryPermission p : permissions) {
                    System.out.format("%s %n", p);
                }

            }
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

輸出結果為

Principal: BUILTIN\Administrators (Alias)
Type: ALLOW
Permissions are:
WRITE_DATA 
WRITE_OWNER 
APPEND_DATA 
SYNCHRONIZE 
WRITE_ATTRIBUTES 
EXECUTE 
READ_DATA 
DELETE_CHILD 
READ_ATTRIBUTES 
WRITE_NAMED_ATTRS 
WRITE_ACL 
DELETE 
READ_ACL 
READ_NAMED_ATTRS 
Principal: NT AUTHORITY\SYSTEM (Well-known group)
Type: ALLOW
Permissions are:
WRITE_DATA 
WRITE_OWNER 
APPEND_DATA 
SYNCHRONIZE 
WRITE_ATTRIBUTES 
EXECUTE 
READ_DATA 
DELETE_CHILD 
READ_ATTRIBUTES 
WRITE_NAMED_ATTRS 
WRITE_ACL 
DELETE 
READ_ACL 
READ_NAMED_ATTRS 
Principal: NT AUTHORITY\Authenticated Users (Well-known group)
Type: ALLOW
Permissions are:
WRITE_DATA 
READ_ATTRIBUTES 
APPEND_DATA 
WRITE_NAMED_ATTRS 
SYNCHRONIZE 
WRITE_ATTRIBUTES 
EXECUTE 
DELETE 
READ_DATA 
READ_ACL 
READ_NAMED_ATTRS 
Principal: BUILTIN\Users (Alias)
Type: ALLOW
Permissions are:
READ_ATTRIBUTES 
SYNCHRONIZE 
EXECUTE 
READ_DATA 
READ_ACL 
READ_NAMED_ATTRS 

（2）為指定用戶添加新的ACL條目

e:/test1.txt為用戶abc添加DATA_READ和DATA_ WRITE權限

import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.*;
import java.util.EnumSet;
import java.util.List;
import java.util.Set;

import static java.nio.file.attribute.AclEntryPermission.READ_DATA;
import static java.nio.file.attribute.AclEntryPermission.WRITE_DATA;

public class Main {
    public static void main(String[] args) {
        
        Path path = Paths.get("e:/test1.txt");
        AclFileAttributeView aclView = Files.getFileAttributeView(path,
                AclFileAttributeView.class);
        if (aclView == null) {
            System.out.format("ACL view  is not  supported.%n");
            return;
        }
        try {

            UserPrincipal bRiceUser = FileSystems.getDefault()
                    .getUserPrincipalLookupService().lookupPrincipalByName("abc");

            Set<AclEntryPermission> permissions = EnumSet.of(READ_DATA, WRITE_DATA);

            AclEntry.Builder builder = AclEntry.newBuilder();
            builder.setPrincipal(bRiceUser);
            builder.setType(AclEntryType.ALLOW);
            builder.setPermissions(permissions);
            AclEntry newEntry = builder.build();

            List<AclEntry> aclEntries = aclView.getAcl();

            aclEntries.add(newEntry);

            aclView.setAcl(aclEntries);
        }catch (IOException e){
            e.printStackTrace();
        }
    }
}

輸出結果比剛才多了

Principal: hkgi-PC\abc (User)
Type: ALLOW
Permissions are:
WRITE_DATA
READ_DATA

3.POSIX文件權限

UNIX支持POSIX標准文件屬性

PosixFilePermission枚舉類型定義九個常量，每個權限組件一個。

九個常數命名為X_Y，其中X是OWNER，GROUP和OTHERS，Y是READ，WRITE和EXECUTE。

PosixFilePermissions的toString()方法將一組PosixFilePermission枚舉常量轉換為rwxrwxrwx形式的字符串

PosixFileAttributeView的setPermissions()方法用來設置權限

（1）輸出/www/test1.txt的權限

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.*;
import java.util.Set;

public class Main {
    public static void main(String[] args) {

        Path path = Paths.get("/www/test1.txt");
        PosixFileAttributeView posixView = Files.getFileAttributeView(path,
                PosixFileAttributeView.class);
        try{
            PosixFileAttributes attribs = posixView.readAttributes();
            Set<PosixFilePermission> permissions = attribs.permissions();
            // Convert the file permissions into the rwxrwxrwx string form
            String rwxFormPermissions = PosixFilePermissions.toString(permissions);
            // Print the permissions
            System.out.println(rwxFormPermissions);
        }catch (IOException e){
            e.printStackTrace();
        }

    }
}

輸出結果

rw-r--r--

（2）讀取和更新名為test的文件權限

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.*;
import java.util.EnumSet;
import java.util.Set;

import static java.nio.file.attribute.PosixFilePermission.*;

public class Main {
    public static void main(String[] args) {

        Path path = Paths.get("/www/test1.txt");
        PosixFileAttributeView posixView = Files.getFileAttributeView(path,
                PosixFileAttributeView.class);

        if (posixView == null) {
            System.out.format("POSIX attribute view  is not  supported%n.");
            return;
        }
        System.out.println("old:");
        readPermissions(posixView);
        updatePermissions(posixView);
        System.out.println("new:");
        readPermissions(posixView);

    }

    public static void readPermissions(PosixFileAttributeView posixView) {
        try{
            PosixFileAttributes attribs;
            attribs = posixView.readAttributes();
            Set<PosixFilePermission> permissions = attribs.permissions();
            // Convert the set of posix file permissions into rwxrwxrwx form
            String rwxFormPermissions = PosixFilePermissions.toString(permissions);
            System.out.println(rwxFormPermissions);
        }catch (IOException e){
            e.printStackTrace();
        }

    }
    public static void updatePermissions(PosixFileAttributeView posixView) {
        try {
            Set<PosixFilePermission> permissions = EnumSet.of(OWNER_READ, OWNER_WRITE,OWNER_EXECUTE,
                    GROUP_READ,GROUP_WRITE);
            posixView.setPermissions(permissions);
            System.out.println("Permissions set successfully.");
        }catch (IOException e){
            e.printStackTrace();
        }
    }
}

輸出結果

old:
rw-r-----
Permissions set successfully.
new:
rwxrw----