1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19
20 package javax.mail.util;
21
22 import java.io.ByteArrayInputStream;
23 import java.io.IOException;
24 import java.io.InputStream;
25
26 import javax.mail.internet.SharedInputStream;
27
28 public class SharedByteArrayInputStream extends ByteArrayInputStream implements SharedInputStream {
29
30 /**
31 * Position within shared buffer that this stream starts at.
32 */
33 protected int start;
34
35 /**
36 * Create a SharedByteArrayInputStream that shares the entire
37 * buffer.
38 *
39 * @param buf The input data.
40 */
41 public SharedByteArrayInputStream(byte[] buf) {
42 this(buf, 0, buf.length);
43 }
44
45
46 /**
47 * Create a SharedByteArrayInputStream using a subset of the
48 * array data.
49 *
50 * @param buf The source data array.
51 * @param offset The starting offset within the array.
52 * @param length The length of data to use.
53 */
54 public SharedByteArrayInputStream(byte[] buf, int offset, int length) {
55 super(buf, offset, length);
56 start = offset;
57 }
58
59
60 /**
61 * Get the position within the output stream, adjusted by the
62 * starting offset.
63 *
64 * @return The adjusted position within the stream.
65 */
66 public long getPosition() {
67 return pos - start;
68 }
69
70
71 /**
72 * Create a new input stream from this input stream, accessing
73 * a subset of the data. Think of it as a substring operation
74 * for a stream.
75 *
76 * The starting offset must be non-negative. The end offset can
77 * by -1, which means use the remainder of the stream.
78 *
79 * @param offset The starting offset.
80 * @param end The end offset (which can be -1).
81 *
82 * @return An InputStream configured to access the indicated data subrange.
83 */
84 public InputStream newStream(long offset, long end) {
85 if (offset < 0) {
86 throw new IllegalArgumentException("Starting position must be non-negative");
87 }
88 if (end == -1) {
89 end = count - start;
90 }
91 return new SharedByteArrayInputStream(buf, start + (int)offset, (int)(end - offset));
92 }
93 }