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.logging.log4j.core.util;
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 * <code>java.io.StringWriter</code>, 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 * <code>java.io.StringWriter</code> should be used.
30 *
31 * Copied from Apache Commons IO revision 1681000.
32 */
33 public class StringBuilderWriter extends Writer implements Serializable {
34
35 private static final long serialVersionUID = -146927496096066153L;
36 private final StringBuilder builder;
37
38 /**
39 * Construct a new {@link StringBuilder} instance with default capacity.
40 */
41 public StringBuilderWriter() {
42 this.builder = new StringBuilder();
43 }
44
45 /**
46 * Construct a new {@link StringBuilder} instance with the specified capacity.
47 *
48 * @param capacity The initial capacity of the underlying {@link StringBuilder}
49 */
50 public StringBuilderWriter(final int capacity) {
51 this.builder = new StringBuilder(capacity);
52 }
53
54 /**
55 * Construct a new instance with the specified {@link StringBuilder}.
56 *
57 * <p>If {@code builder} is null a new instance with default capacity will be created.</p>
58 *
59 * @param builder The String builder. May be null.
60 */
61 public StringBuilderWriter(final StringBuilder builder) {
62 this.builder = builder != null ? builder : new StringBuilder();
63 }
64
65 /**
66 * Append a single character to this Writer.
67 *
68 * @param value The character to append
69 * @return This writer instance
70 */
71 @Override
72 public Writer append(final char value) {
73 builder.append(value);
74 return this;
75 }
76
77 /**
78 * Append a character sequence to this Writer.
79 *
80 * @param value The character to append
81 * @return This writer instance
82 */
83 @Override
84 public Writer append(final CharSequence value) {
85 builder.append(value);
86 return this;
87 }
88
89 /**
90 * Append a portion of a character sequence to the {@link StringBuilder}.
91 *
92 * @param value The character to append
93 * @param start The index of the first character
94 * @param end The index of the last character + 1
95 * @return This writer instance
96 */
97 @Override
98 public Writer append(final CharSequence value, final int start, final int end) {
99 builder.append(value, start, end);
100 return this;
101 }
102
103 /**
104 * Closing this writer has no effect.
105 */
106 @Override
107 public void close() {
108 // no-op
109 }
110
111 /**
112 * Flushing this writer has no effect.
113 */
114 @Override
115 public void flush() {
116 // no-op
117 }
118
119
120 /**
121 * Write a String to the {@link StringBuilder}.
122 *
123 * @param value The value to write
124 */
125 @Override
126 public void write(final String value) {
127 if (value != null) {
128 builder.append(value);
129 }
130 }
131
132 /**
133 * Write a portion of a character array to the {@link StringBuilder}.
134 *
135 * @param value The value to write
136 * @param offset The index of the first character
137 * @param length The number of characters to write
138 */
139 @Override
140 public void write(final char[] value, final int offset, final int length) {
141 if (value != null) {
142 builder.append(value, offset, length);
143 }
144 }
145
146 /**
147 * Return the underlying builder.
148 *
149 * @return The underlying builder
150 */
151 public StringBuilder getBuilder() {
152 return builder;
153 }
154
155 /**
156 * Returns {@link StringBuilder#toString()}.
157 *
158 * @return The contents of the String builder.
159 */
160 @Override
161 public String toString() {
162 return builder.toString();
163 }
164 }