FileOwnerAttributeView.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
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package java.nio.file.attribute;

import java.io.IOException;

/**
 * A file attribute view that supports reading or updating the owner of a file.
 * This file attribute view is intended for file system implementations that
 * support a file attribute that represents an identity that is the owner of
 * the file. Often the owner of a file is the identity of the entity that
 * created the file.
 *
 * <p> The {@link #getOwner getOwner} or {@link #setOwner setOwner} methods may
 * be used to read or update the owner of the file.
 *
 * <p> The {@link java.nio.file.Files#getAttribute getAttribute} and
 * {@link java.nio.file.Files#setAttribute setAttribute} methods may also be
 * used to read or update the owner. In that case, the owner attribute is
 * identified by the name {@code "owner"}, and the value of the attribute is
 * a {@link UserPrincipal}.
 *
 * @since 1.7
 */
/*
 * "owner"文件属性视图接口，可以获取/设置文件所有者信息
 *
 * 注：不同的操作系统平台会有不同的实现机制
 * 在windows上，该实现是委托给AclFileAttributeView来完成的；
 * 在linux和mac上，该实现是委托给PosixFileAttributeView来完成的。
 */
public interface FileOwnerAttributeView extends FileAttributeView {
    
    /**
     * Returns the name of the attribute view. Attribute views of this type
     * have the name {@code "owner"}.
     */
    // 返回当前属性视图的名称，通常返回"owner"
    @Override
    String name();
    
    /**
     * Read the file owner.
     *
     * <p> It is implementation specific if the file owner can be a {@link
     * GroupPrincipal group}.
     *
     * @return the file owner
     *
     * @throws IOException       if an I/O error occurs
     * @throws SecurityException In the case of the default provider, a security manager is
     *                           installed, and it denies {@link
     *                           RuntimePermission}{@code ("accessUserInformation")} or its
     *                           {@link SecurityManager#checkRead(String) checkRead} method
     *                           denies read access to the file.
     */
    // 返回关联文件的所有者
    UserPrincipal getOwner() throws IOException;
    
    /**
     * Updates the file owner.
     *
     * <p> It is implementation specific if the file owner can be a {@link
     * GroupPrincipal group}. To ensure consistent and correct behavior
     * across platforms it is recommended that this method should only be used
     * to set the file owner to a user principal that is not a group.
     *
     * @param owner the new file owner
     *
     * @throws IOException       if an I/O error occurs, or the {@code owner} parameter is a
     *                           group and this implementation does not support setting the owner
     *                           to a group
     * @throws SecurityException In the case of the default provider, a security manager is
     *                           installed, and it denies {@link
     *                           RuntimePermission}{@code ("accessUserInformation")} or its
     *                           {@link SecurityManager#checkWrite(String) checkWrite} method
     *                           denies write access to the file.
     */
    // 更新/设置关联文件的所有者信息
    void setOwner(UserPrincipal owner) throws IOException;
    
}