1 /*
2 * Copyright (c) 2003, 2013, 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.lang;
27
28 import java.io.IOException;
29
30 /**
31 * A {@code Readable} is a source of characters. Characters from
32 * a {@code Readable} are made available to callers of the read
33 * method via a {@link java.nio.CharBuffer CharBuffer}.
34 *
35 * @since 1.5
36 */
37 public interface Readable {
38
39 /**
40 * Attempts to read characters into the specified character buffer.
41 * The buffer is used as a repository of characters as-is: the only
42 * changes made are the results of a put operation. No flipping or
43 * rewinding of the buffer is performed.
44 *
45 * @param cb the buffer to read characters into
46 * @return The number of {@code char} values added to the buffer,
47 * or -1 if this source of characters is at its end
48 * @throws IOException if an I/O error occurs
49 * @throws NullPointerException if cb is null
50 * @throws java.nio.ReadOnlyBufferException if cb is a read only buffer
51 */
52 public int read(java.nio.CharBuffer cb) throws IOException;
53 }
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1 /*
2 * Copyright (c) 2003, 2017, 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.lang;
27
28 import java.io.IOException;
29 import java.nio.CharBuffer;
30 import java.util.Objects;
31
32 /**
33 * A {@code Readable} is a source of characters. Characters from
34 * a {@code Readable} are made available to callers of the read
35 * method via a {@link java.nio.CharBuffer CharBuffer}.
36 *
37 * @since 1.5
38 */
39 public interface Readable {
40
41 /**
42 * Attempts to read characters into the specified character buffer.
43 * The buffer is used as a repository of characters as-is: the only
44 * changes made are the results of a put operation. No flipping or
45 * rewinding of the buffer is performed.
46 *
47 * @param cb the buffer to read characters into
48 * @return The number of {@code char} values added to the buffer,
49 * or -1 if this source of characters is at its end
50 * @throws IOException if an I/O error occurs
51 * @throws NullPointerException if cb is null
52 * @throws java.nio.ReadOnlyBufferException if cb is a read only buffer
53 */
54 public int read(java.nio.CharBuffer cb) throws IOException;
55
56 /**
57 * Reads all characters from this source and appends them to a destination
58 * in the order in which they are read. On return, the source of characters
59 * will be at its end.
60 * <p>
61 * This method may block indefinitely while reading from the source or
62 * writing to the destination. If the source or destination is
63 * {@link AutoCloseable closeable}, then the behavior when either is
64 * <i>asynchronously closed</i>, or the thread is interrupted during the
65 * transfer, is highly implementation-dependent and hence unspecified.
66 * <p>
67 * If an I/O error occurs during the operation, then not all characters
68 * might have been transferred and the source or destination could be
69 * left in an inconsistent state. The caller of this method should therefore
70 * ensure in such a case that measures are taken to release any resources
71 * held by the source and destination.
72 *
73 * @implSpec
74 * The default implementation invokes the read method to read all characters
75 * from this source and invokes the {@link Appendable#append(CharSequence, int, int)}
76 * method to write all characters to the appendable.
77 * The total amount will be added up by after the write method has been
78 * completed.
79 *
80 * The default implementation behaves as if:
81 * <pre>{@code
82 * long transferred = 0;
83 * CharBuffer buffer = CharBuffer.allocate(8192);
84 * int read;
85 * while ((read = this.read(buffer)) >= 0) {
86 * buffer.rewind();
87 * out.append(buffer, 0, read);
88 * transferred += read;
89 * }
90 * return transferred;
91 * }</pre>
92 *
93 * @implNote
94 * The default implementation should usually be overridden in cases where
95 * the implementer is already a {@link CharSequence} or its data is already
96 * available in the internal representation in order not having the extra
97 * overhead creating a buffer in order to transfer its data to the
98 * destination.
99 *
100 * @param out the appendable, non-null
101 * @return the number of characters transferred
102 * @throws IOException if an I/O error occurs when reading or writing
103 * @throws NullPointerException if {@code out} is {@code null}
104 *
105 * @since 10
106 */
107 public default long transferTo(Appendable out) throws IOException {
108 Objects.requireNonNull(out, "out");
109 long transferred = 0;
110 CharBuffer buffer = CharBuffer.allocate(8192);
111 int read;
112 while ((read = this.read(buffer)) >= 0) {
113 buffer.rewind();
114 out.append(buffer, 0, read);
115 transferred += read;
116 }
117 return transferred;
118 }
119 }
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