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My first initial commit with all of mine experimental changes.

Dmitry Kabak (userdima committed 13 years ago

Commit d37b88d1 parent 3f5b46618352 files · +2598093 −-8690Browse files

Showing the changes to java/pkg/java/io/SequenceInputStream.java (1 of 18352 files). Show all

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java/pkg/java/io/SequenceInputStream.java+235−0
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1+/*
2+ * Copyright (c) 1994, 2006, Oracle and/or its affiliates. All rights reserved.
3+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4+ *
5+ * This code is free software; you can redistribute it and/or modify it
6+ * under the terms of the GNU General Public License version 2 only, as
7+ * published by the Free Software Foundation. Oracle designates this
8+ * particular file as subject to the "Classpath" exception as provided
9+ * by Oracle in the LICENSE file that accompanied this code.
10+ *
11+ * This code is distributed in the hope that it will be useful, but WITHOUT
12+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14+ * version 2 for more details (a copy is included in the LICENSE file that
15+ * accompanied this code).
16+ *
17+ * You should have received a copy of the GNU General Public License version
18+ * 2 along with this work; if not, write to the Free Software Foundation,
19+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20+ *
21+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22+ * or visit www.oracle.com if you need additional information or have any
23+ * questions.
24+ */
25+
26+package java.io;
27+
28+import java.io.InputStream;
29+import java.util.Enumeration;
30+import java.util.Vector;
31+
32+/**
33+ * A <code>SequenceInputStream</code> represents
34+ * the logical concatenation of other input
35+ * streams. It starts out with an ordered
36+ * collection of input streams and reads from
37+ * the first one until end of file is reached,
38+ * whereupon it reads from the second one,
39+ * and so on, until end of file is reached
40+ * on the last of the contained input streams.
41+ *
42+ * @author Author van Hoff
43+ * @since JDK1.0
44+ */
45+public
46+class SequenceInputStream extends InputStream {
47+ Enumeration e;
48+ InputStream in;
49+
50+ /**
51+ * Initializes a newly created <code>SequenceInputStream</code>
52+ * by remembering the argument, which must
53+ * be an <code>Enumeration</code> that produces
54+ * objects whose run-time type is <code>InputStream</code>.
55+ * The input streams that are produced by
56+ * the enumeration will be read, in order,
57+ * to provide the bytes to be read from this
58+ * <code>SequenceInputStream</code>. After
59+ * each input stream from the enumeration
60+ * is exhausted, it is closed by calling its
61+ * <code>close</code> method.
62+ *
63+ * @param e an enumeration of input streams.
64+ * @see java.util.Enumeration
65+ */
66+ public SequenceInputStream(Enumeration<? extends InputStream> e) {
67+ this.e = e;
68+ try {
69+ nextStream();
70+ } catch (IOException ex) {
71+ // This should never happen
72+ throw new Error("panic");
73+ }
74+ }
75+
76+ /**
77+ * Initializes a newly
78+ * created <code>SequenceInputStream</code>
79+ * by remembering the two arguments, which
80+ * will be read in order, first <code>s1</code>
81+ * and then <code>s2</code>, to provide the
82+ * bytes to be read from this <code>SequenceInputStream</code>.
83+ *
84+ * @param s1 the first input stream to read.
85+ * @param s2 the second input stream to read.
86+ */
87+ public SequenceInputStream(InputStream s1, InputStream s2) {
88+ Vector v = new Vector(2);
89+
90+ v.addElement(s1);
91+ v.addElement(s2);
92+ e = v.elements();
93+ try {
94+ nextStream();
95+ } catch (IOException ex) {
96+ // This should never happen
97+ throw new Error("panic");
98+ }
99+ }
100+
101+ /**
102+ * Continues reading in the next stream if an EOF is reached.
103+ */
104+ final void nextStream() throws IOException {
105+ if (in != null) {
106+ in.close();
107+ }
108+
109+ if (e.hasMoreElements()) {
110+ in = (InputStream) e.nextElement();
111+ if (in == null)
112+ throw new NullPointerException();
113+ }
114+ else in = null;
115+
116+ }
117+
118+ /**
119+ * Returns an estimate of the number of bytes that can be read (or
120+ * skipped over) from the current underlying input stream without
121+ * blocking by the next invocation of a method for the current
122+ * underlying input stream. The next invocation might be
123+ * the same thread or another thread. A single read or skip of this
124+ * many bytes will not block, but may read or skip fewer bytes.
125+ * <p>
126+ * This method simply calls {@code available} of the current underlying
127+ * input stream and returns the result.
128+ *
129+ * @return an estimate of the number of bytes that can be read (or
130+ * skipped over) from the current underlying input stream
131+ * without blocking or {@code 0} if this input stream
132+ * has been closed by invoking its {@link #close()} method
133+ * @exception IOException if an I/O error occurs.
134+ *
135+ * @since JDK1.1
136+ */
137+ public int available() throws IOException {
138+ if(in == null) {
139+ return 0; // no way to signal EOF from available()
140+ }
141+ return in.available();
142+ }
143+
144+ /**
145+ * Reads the next byte of data from this input stream. The byte is
146+ * returned as an <code>int</code> in the range <code>0</code> to
147+ * <code>255</code>. If no byte is available because the end of the
148+ * stream has been reached, the value <code>-1</code> is returned.
149+ * This method blocks until input data is available, the end of the
150+ * stream is detected, or an exception is thrown.
151+ * <p>
152+ * This method
153+ * tries to read one character from the current substream. If it
154+ * reaches the end of the stream, it calls the <code>close</code>
155+ * method of the current substream and begins reading from the next
156+ * substream.
157+ *
158+ * @return the next byte of data, or <code>-1</code> if the end of the
159+ * stream is reached.
160+ * @exception IOException if an I/O error occurs.
161+ */
162+ public int read() throws IOException {
163+ if (in == null) {
164+ return -1;
165+ }
166+ int c = in.read();
167+ if (c == -1) {
168+ nextStream();
169+ return read();
170+ }
171+ return c;
172+ }
173+
174+ /**
175+ * Reads up to <code>len</code> bytes of data from this input stream
176+ * into an array of bytes. If <code>len</code> is not zero, the method
177+ * blocks until at least 1 byte of input is available; otherwise, no
178+ * bytes are read and <code>0</code> is returned.
179+ * <p>
180+ * The <code>read</code> method of <code>SequenceInputStream</code>
181+ * tries to read the data from the current substream. If it fails to
182+ * read any characters because the substream has reached the end of
183+ * the stream, it calls the <code>close</code> method of the current
184+ * substream and begins reading from the next substream.
185+ *
186+ * @param b the buffer into which the data is read.
187+ * @param off the start offset in array <code>b</code>
188+ * at which the data is written.
189+ * @param len the maximum number of bytes read.
190+ * @return int the number of bytes read.
191+ * @exception NullPointerException If <code>b</code> is <code>null</code>.
192+ * @exception IndexOutOfBoundsException If <code>off</code> is negative,
193+ * <code>len</code> is negative, or <code>len</code> is greater than
194+ * <code>b.length - off</code>
195+ * @exception IOException if an I/O error occurs.
196+ */
197+ public int read(byte b[], int off, int len) throws IOException {
198+ if (in == null) {
199+ return -1;
200+ } else if (b == null) {
201+ throw new NullPointerException();
202+ } else if (off < 0 || len < 0 || len > b.length - off) {
203+ throw new IndexOutOfBoundsException();
204+ } else if (len == 0) {
205+ return 0;
206+ }
207+
208+ int n = in.read(b, off, len);
209+ if (n <= 0) {
210+ nextStream();
211+ return read(b, off, len);
212+ }
213+ return n;
214+ }
215+
216+ /**
217+ * Closes this input stream and releases any system resources
218+ * associated with the stream.
219+ * A closed <code>SequenceInputStream</code>
220+ * cannot perform input operations and cannot
221+ * be reopened.
222+ * <p>
223+ * If this stream was created
224+ * from an enumeration, all remaining elements
225+ * are requested from the enumeration and closed
226+ * before the <code>close</code> method returns.
227+ *
228+ * @exception IOException if an I/O error occurs.
229+ */
230+ public void close() throws IOException {
231+ do {
232+ nextStream();
233+ } while (in != null);
234+ }
235+}