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.Serializable;
20 import java.io.Writer;
21
22 /**
23 * {@link Writer} implementation that outputs to a {@link StringBuilder}.
24 * <p>
25 * <strong>NOTE:</strong> This implementation, as an alternative to
26 * {@link java.io.StringWriter}, provides an <i>un-synchronized</i>
27 * (i.e. for use in a single thread) implementation for better performance.
28 * For safe usage with multiple {@link Thread}s then
29 * {@link java.io.StringWriter} should be used.
30 * </p>
31 * <h2>Deprecating Serialization</h2>
32 * <p>
33 * <em>Serialization is deprecated and will be removed in 3.0.</em>
34 * </p>
35 * @since 2.0
36 */
37 public class StringBuilderWriter extends Writer implements Serializable {
38
39 private static final long serialVersionUID = -146927496096066153L;
40
41 /** The append target. */
42 private final StringBuilder builder;
43
44 /**
45 * Constructs a new {@link StringBuilder} instance with default capacity.
46 */
47 public StringBuilderWriter() {
48 this.builder = new StringBuilder();
49 }
50
51 /**
52 * Constructs a new {@link StringBuilder} instance with the specified capacity.
53 *
54 * @param capacity The initial capacity of the underlying {@link StringBuilder}
55 */
56 public StringBuilderWriter(final int capacity) {
57 this.builder = new StringBuilder(capacity);
58 }
59
60 /**
61 * Constructs a new instance with the specified {@link StringBuilder}.
62 *
63 * <p>If {@code builder} is null a new instance with default capacity will be created.</p>
64 *
65 * @param builder The String builder. May be null.
66 */
67 public StringBuilderWriter(final StringBuilder builder) {
68 this.builder = builder != null ? builder : new StringBuilder();
69 }
70
71 /**
72 * Appends a single character to this Writer.
73 *
74 * @param value The character to append
75 * @return This writer instance
76 */
77 @Override
78 public Writer append(final char value) {
79 builder.append(value);
80 return this;
81 }
82
83 /**
84 * Appends a character sequence to this Writer.
85 *
86 * @param value The character to append
87 * @return This writer instance
88 */
89 @Override
90 public Writer append(final CharSequence value) {
91 builder.append(value);
92 return this;
93 }
94
95 /**
96 * Appends a portion of a character sequence to the {@link StringBuilder}.
97 *
98 * @param value The character to append
99 * @param start The index of the first character
100 * @param end The index of the last character + 1
101 * @return This writer instance
102 */
103 @Override
104 public Writer append(final CharSequence value, final int start, final int end) {
105 builder.append(value, start, end);
106 return this;
107 }
108
109 /**
110 * Closing this writer has no effect.
111 */
112 @Override
113 public void close() {
114 // no-op
115 }
116
117 /**
118 * Flushing this writer has no effect.
119 */
120 @Override
121 public void flush() {
122 // no-op
123 }
124
125 /**
126 * Gets the underlying builder.
127 *
128 * @return The underlying builder
129 */
130 public StringBuilder getBuilder() {
131 return builder;
132 }
133
134 /**
135 * Returns {@link StringBuilder#toString()}.
136 *
137 * @return The contents of the String builder.
138 */
139 @Override
140 public String toString() {
141 return builder.toString();
142 }
143
144 /**
145 * Writes a portion of a character array to the {@link StringBuilder}.
146 *
147 * @param value The value to write
148 * @param offset The index of the first character
149 * @param length The number of characters to write
150 */
151 @Override
152 public void write(final char[] value, final int offset, final int length) {
153 if (value != null) {
154 builder.append(value, offset, length);
155 }
156 }
157
158 /**
159 * Writes a String to the {@link StringBuilder}.
160 *
161 * @param value The value to write
162 */
163 @Override
164 public void write(final String value) {
165 if (value != null) {
166 builder.append(value);
167 }
168 }
169 }