JDK8/Java8源码在线阅读
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* published by the Free Software Foundation. Oracle designates this
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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,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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package java.nio.file.attribute;
import java.util.*;
/**
* An entry in an access control list (ACL).
*
* <p> The ACL entry represented by this class is based on the ACL model
* specified in <a href="http://www.ietf.org/rfc/rfc3530.txt"><i>RFC 3530:
* Network File System (NFS) version 4 Protocol</i></a>. Each entry has four
* components as follows:
*
* <ol>
* <li><p> The {@link #type() type} component determines if the entry
* grants or denies access. </p></li>
*
* <li><p> The {@link #principal() principal} component, sometimes called the
* "who" component, is a {@link UserPrincipal} corresponding to the identity
* that the entry grants or denies access
* </p></li>
*
* <li><p> The {@link #permissions permissions} component is a set of
* {@link AclEntryPermission permissions}
* </p></li>
*
* <li><p> The {@link #flags flags} component is a set of {@link AclEntryFlag
* flags} to indicate how entries are inherited and propagated </p></li>
* </ol>
*
* <p> ACL entries are created using an associated {@link Builder} object by
* invoking its {@link Builder#build build} method.
*
* <p> ACL entries are immutable and are safe for use by multiple concurrent
* threads.
*
* @since 1.7
*/
public final class AclEntry {
private final AclEntryType type;
private final UserPrincipal who;
private final Set<AclEntryPermission> perms;
private final Set<AclEntryFlag> flags;
// cached hash code
private volatile int hash;
// private constructor
private AclEntry(AclEntryType type,
UserPrincipal who,
Set<AclEntryPermission> perms,
Set<AclEntryFlag> flags)
{
this.type = type;
this.who = who;
this.perms = perms;
this.flags = flags;
}
/**
* A builder of {@link AclEntry} objects.
*
* <p> A {@code Builder} object is obtained by invoking one of the {@link
* AclEntry#newBuilder newBuilder} methods defined by the {@code AclEntry}
* class.
*
* <p> Builder objects are mutable and are not safe for use by multiple
* concurrent threads without appropriate synchronization.
*
* @since 1.7
*/
public static final class Builder {
private AclEntryType type;
private UserPrincipal who;
private Set<AclEntryPermission> perms;
private Set<AclEntryFlag> flags;
private Builder(AclEntryType type,
UserPrincipal who,
Set<AclEntryPermission> perms,
Set<AclEntryFlag> flags)
{
assert perms != null && flags != null;
this.type = type;
this.who = who;
this.perms = perms;
this.flags = flags;
}
/**
* Constructs an {@link AclEntry} from the components of this builder.
* The type and who components are required to have been set in order
* to construct an {@code AclEntry}.
*
* @return a new ACL entry
*
* @throws IllegalStateException
* if the type or who component have not been set
*/
public AclEntry build() {
if (type == null)
throw new IllegalStateException("Missing type component");
if (who == null)
throw new IllegalStateException("Missing who component");
return new AclEntry(type, who, perms, flags);
}
/**
* Sets the type component of this builder.
*
* @param type the component type
* @return this builder
*/
public Builder setType(AclEntryType type) {
if (type == null)
throw new NullPointerException();
this.type = type;
return this;
}
/**
* Sets the principal component of this builder.
*
* @param who the principal component
* @return this builder
*/
public Builder setPrincipal(UserPrincipal who) {
if (who == null)
throw new NullPointerException();
this.who = who;
return this;
}
// check set only contains elements of the given type
private static void checkSet(Set<?> set, Class<?> type) {
for (Object e: set) {
if (e == null)
throw new NullPointerException();
type.cast(e);
}
}
/**
* Sets the permissions component of this builder. On return, the
* permissions component of this builder is a copy of the given set.
*
* @param perms the permissions component
* @return this builder
*
* @throws ClassCastException
* if the set contains elements that are not of type {@code
* AclEntryPermission}
*/
public Builder setPermissions(Set<AclEntryPermission> perms) {
if (perms.isEmpty()) {
// EnumSet.copyOf does not allow empty set
perms = Collections.emptySet();
} else {
// copy and check for erroneous elements
perms = EnumSet.copyOf(perms);
checkSet(perms, AclEntryPermission.class);
}
this.perms = perms;
return this;
}
/**
* Sets the permissions component of this builder. On return, the
* permissions component of this builder is a copy of the permissions in
* the given array.
*
* @param perms the permissions component
* @return this builder
*/
public Builder setPermissions(AclEntryPermission... perms) {
Set<AclEntryPermission> set = EnumSet.noneOf(AclEntryPermission.class);
// copy and check for null elements
for (AclEntryPermission p: perms) {
if (p == null)
throw new NullPointerException();
set.add(p);
}
this.perms = set;
return this;
}
/**
* Sets the flags component of this builder. On return, the flags
* component of this builder is a copy of the given set.
*
* @param flags the flags component
* @return this builder
*
* @throws ClassCastException
* if the set contains elements that are not of type {@code
* AclEntryFlag}
*/
public Builder setFlags(Set<AclEntryFlag> flags) {
if (flags.isEmpty()) {
// EnumSet.copyOf does not allow empty set
flags = Collections.emptySet();
} else {
// copy and check for erroneous elements
flags = EnumSet.copyOf(flags);
checkSet(flags, AclEntryFlag.class);
}
this.flags = flags;
return this;
}
/**
* Sets the flags component of this builder. On return, the flags
* component of this builder is a copy of the flags in the given
* array.
*
* @param flags the flags component
* @return this builder
*/
public Builder setFlags(AclEntryFlag... flags) {
Set<AclEntryFlag> set = EnumSet.noneOf(AclEntryFlag.class);
// copy and check for null elements
for (AclEntryFlag f: flags) {
if (f == null)
throw new NullPointerException();
set.add(f);
}
this.flags = set;
return this;
}
}
/**
* Constructs a new builder. The initial value of the type and who
* components is {@code null}. The initial value of the permissions and
* flags components is the empty set.
*
* @return a new builder
*/
public static Builder newBuilder() {
Set<AclEntryPermission> perms = Collections.emptySet();
Set<AclEntryFlag> flags = Collections.emptySet();
return new Builder(null, null, perms, flags);
}
/**
* Constructs a new builder with the components of an existing ACL entry.
*
* @param entry an ACL entry
* @return a new builder
*/
public static Builder newBuilder(AclEntry entry) {
return new Builder(entry.type, entry.who, entry.perms, entry.flags);
}
/**
* Returns the ACL entry type.
*
* @return the ACL entry type
*/
public AclEntryType type() {
return type;
}
/**
* Returns the principal component.
*
* @return the principal component
*/
public UserPrincipal principal() {
return who;
}
/**
* Returns a copy of the permissions component.
*
* <p> The returned set is a modifiable copy of the permissions.
*
* @return the permissions component
*/
public Set<AclEntryPermission> permissions() {
return new HashSet<AclEntryPermission>(perms);
}
/**
* Returns a copy of the flags component.
*
* <p> The returned set is a modifiable copy of the flags.
*
* @return the flags component
*/
public Set<AclEntryFlag> flags() {
return new HashSet<AclEntryFlag>(flags);
}
/**
* Compares the specified object with this ACL entry for equality.
*
* <p> If the given object is not an {@code AclEntry} then this method
* immediately returns {@code false}.
*
* <p> For two ACL entries to be considered equals requires that they are
* both the same type, their who components are equal, their permissions
* components are equal, and their flags components are equal.
*
* <p> This method satisfies the general contract of the {@link
* java.lang.Object#equals(Object) Object.equals} method. </p>
*
* @param ob the object to which this object is to be compared
*
* @return {@code true} if, and only if, the given object is an AclEntry that
* is identical to this AclEntry
*/
@Override
public boolean equals(Object ob) {
if (ob == this)
return true;
if (ob == null || !(ob instanceof AclEntry))
return false;
AclEntry other = (AclEntry)ob;
if (this.type != other.type)
return false;
if (!this.who.equals(other.who))
return false;
if (!this.perms.equals(other.perms))
return false;
if (!this.flags.equals(other.flags))
return false;
return true;
}
private static int hash(int h, Object o) {
return h * 127 + o.hashCode();
}
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