1 /* Licensed to the Apache Software Foundation (ASF) under one or more
2  * contributor license agreements.  See the NOTICE file distributed with
3  * this work for additional information regarding copyright ownership.
4  * The ASF licenses this file to You under the Apache License, Version 2.0
5  * (the "License"); you may not use this file except in compliance with
6  * the License.  You may obtain a copy of the License at
7  *
8  *     http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package java.nio;
18 
19 import java.io.Closeable;
20 import java.io.FileDescriptor;
21 import java.io.IOException;
22 import java.nio.channels.ClosedChannelException;
23 import java.nio.channels.FileChannel;
24 import java.util.Set;
25 
26 /**
27  * @hide internal use only
28  */
29 public final class NioUtils {
NioUtils()30     private NioUtils() {
31     }
32 
freeDirectBuffer(ByteBuffer buffer)33     public static void freeDirectBuffer(ByteBuffer buffer) {
34         if (buffer == null) {
35             return;
36         }
37         ((DirectByteBuffer) buffer).free();
38     }
39 
40     /**
41      * Returns the int file descriptor from within the given FileChannel 'fc'.
42      */
getFD(FileChannel fc)43     public static FileDescriptor getFD(FileChannel fc) {
44         return ((FileChannelImpl) fc).getFD();
45     }
46 
47     /**
48      * Helps bridge between io and nio.
49      */
newFileChannel(Closeable ioObject, FileDescriptor fd, int mode)50     public static FileChannel newFileChannel(Closeable ioObject, FileDescriptor fd, int mode) {
51         return new FileChannelImpl(ioObject, fd, mode);
52     }
53 
54     /**
55      * Exposes the array backing a non-direct ByteBuffer, even if the ByteBuffer is read-only.
56      * Normally, attempting to access the array backing a read-only buffer throws.
57      */
unsafeArray(ByteBuffer b)58     public static byte[] unsafeArray(ByteBuffer b) {
59         return ((ByteArrayBuffer) b).backingArray;
60     }
61 
62     /**
63      * Exposes the array offset for the array backing a non-direct ByteBuffer,
64      * even if the ByteBuffer is read-only.
65      */
unsafeArrayOffset(ByteBuffer b)66     public static int unsafeArrayOffset(ByteBuffer b) {
67         return ((ByteArrayBuffer) b).arrayOffset;
68     }
69 }
70