1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.io.output;
18
19 import java.io.IOException;
20 import java.io.Writer;
21 import java.util.Objects;
22
23 /**
24 * Writer implementation that writes the data to an {@link Appendable}
25 * Object.
26 * <p>
27 * For example, can be used with a {@link StringBuilder}
28 * or {@link StringBuffer}.
29 * </p>
30 *
31 * @since 2.7
32 * @see Appendable
33 *
34 * @param <T> The type of the {@link Appendable} wrapped by this AppendableWriter.
35 */
36 public class AppendableWriter <T extends Appendable> extends Writer {
37
38 private final T appendable;
39
40 /**
41 * Constructs a new instance with the specified appendable.
42 *
43 * @param appendable the appendable to write to
44 */
45 public AppendableWriter(final T appendable) {
46 this.appendable = appendable;
47 }
48
49 /**
50 * Appends the specified character to the underlying appendable.
51 *
52 * @param c the character to append
53 * @return this writer
54 * @throws IOException upon error
55 */
56 @Override
57 public Writer append(final char c) throws IOException {
58 appendable.append(c);
59 return this;
60 }
61
62 /**
63 * Appends the specified character sequence to the underlying appendable.
64 *
65 * @param csq the character sequence to append
66 * @return this writer
67 * @throws IOException upon error
68 */
69 @Override
70 public Writer append(final CharSequence csq) throws IOException {
71 appendable.append(csq);
72 return this;
73 }
74
75 /**
76 * Appends a subsequence of the specified character sequence to the underlying appendable.
77 *
78 * @param csq the character sequence from which a subsequence will be appended
79 * @param start the index of the first character in the subsequence
80 * @param end the index of the character following the last character in the subsequence
81 * @return this writer
82 * @throws IOException upon error
83 */
84 @Override
85 public Writer append(final CharSequence csq, final int start, final int end) throws IOException {
86 appendable.append(csq, start, end);
87 return this;
88 }
89
90 /**
91 * Closes the stream. This implementation does nothing.
92 *
93 * @throws IOException upon error
94 */
95 @Override
96 public void close() throws IOException {
97 // noop
98 }
99
100 /**
101 * Flushes the stream. This implementation does nothing.
102 *
103 * @throws IOException upon error
104 */
105 @Override
106 public void flush() throws IOException {
107 // noop
108 }
109
110 /**
111 * Gets the target appendable.
112 *
113 * @return the target appendable
114 */
115 public T getAppendable() {
116 return appendable;
117 }
118
119 /**
120 * Writes a portion of an array of characters to the underlying appendable.
121 *
122 * @param cbuf an array with the characters to write
123 * @param off offset from which to start writing characters
124 * @param len number of characters to write
125 * @throws IOException upon error
126 */
127 @Override
128 public void write(final char[] cbuf, final int off, final int len) throws IOException {
129 Objects.requireNonNull(cbuf, "Character array is missing");
130 if (len < 0 || off + len > cbuf.length) {
131 throw new IndexOutOfBoundsException("Array Size=" + cbuf.length +
132 ", offset=" + off + ", length=" + len);
133 }
134 for (int i = 0; i < len; i++) {
135 appendable.append(cbuf[off + i]);
136 }
137 }
138
139 /**
140 * Writes a character to the underlying appendable.
141 *
142 * @param c the character to write
143 * @throws IOException upon error
144 */
145 @Override
146 public void write(final int c) throws IOException {
147 appendable.append((char) c);
148 }
149
150 /**
151 * Writes a portion of a String to the underlying appendable.
152 *
153 * @param str a string
154 * @param off offset from which to start writing characters
155 * @param len number of characters to write
156 * @throws IOException upon error
157 */
158 @Override
159 public void write(final String str, final int off, final int len) throws IOException {
160 // appendable.append will add "null" for a null String; add an explicit null check
161 Objects.requireNonNull(str, "String is missing");
162 appendable.append(str, off, off + len);
163 }
164
165 }