1 | /* |
2 | * Copyright 2006-2014 the original author or authors. |
3 | * |
4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
5 | * you may not use this file except in compliance with the License. |
6 | * You may obtain a copy of the License at |
7 | * |
8 | * http://www.apache.org/licenses/LICENSE-2.0 |
9 | * |
10 | * Unless required by applicable law or agreed to in writing, software |
11 | * distributed under the License is distributed on an "AS IS" BASIS, |
12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
13 | * See the License for the specific language governing permissions and |
14 | * limitations under the License. |
15 | */ |
16 | |
17 | package org.springframework.batch.item.file.transform; |
18 | |
19 | import java.util.ArrayList; |
20 | import java.util.Collection; |
21 | import java.util.HashSet; |
22 | import java.util.List; |
23 | |
24 | import org.springframework.util.Assert; |
25 | import org.springframework.util.StringUtils; |
26 | |
27 | /** |
28 | * A {@link LineTokenizer} implementation that splits the input String on a |
29 | * configurable delimiter. This implementation also supports the use of an |
30 | * escape character to escape delimiters and line endings. |
31 | * |
32 | * @author Rob Harrop |
33 | * @author Dave Syer |
34 | * @author Michael Minella |
35 | */ |
36 | public class DelimitedLineTokenizer extends AbstractLineTokenizer { |
37 | /** |
38 | * Convenient constant for the common case of a tab delimiter. |
39 | */ |
40 | public static final String DELIMITER_TAB = "\t"; |
41 | |
42 | /** |
43 | * Convenient constant for the common case of a comma delimiter. |
44 | */ |
45 | public static final String DELIMITER_COMMA = ","; |
46 | |
47 | /** |
48 | * Convenient constant for the common case of a " character used to escape |
49 | * delimiters or line endings. |
50 | */ |
51 | public static final char DEFAULT_QUOTE_CHARACTER = '"'; |
52 | |
53 | // the delimiter character used when reading input. |
54 | private String delimiter; |
55 | |
56 | private char quoteCharacter = DEFAULT_QUOTE_CHARACTER; |
57 | |
58 | private String quoteString; |
59 | |
60 | private Collection<Integer> includedFields = null; |
61 | |
62 | /** |
63 | * Create a new instance of the {@link DelimitedLineTokenizer} class for the |
64 | * common case where the delimiter is a {@link #DELIMITER_COMMA comma}. |
65 | * |
66 | * @see #DelimitedLineTokenizer(String) |
67 | * @see #DELIMITER_COMMA |
68 | */ |
69 | public DelimitedLineTokenizer() { |
70 | this(DELIMITER_COMMA); |
71 | } |
72 | |
73 | /** |
74 | * Create a new instance of the {@link DelimitedLineTokenizer} class. |
75 | * |
76 | * @param delimiter the desired delimiter |
77 | */ |
78 | public DelimitedLineTokenizer(String delimiter) { |
79 | Assert.state(!delimiter.equals(String.valueOf(DEFAULT_QUOTE_CHARACTER)), "[" + DEFAULT_QUOTE_CHARACTER |
80 | + "] is not allowed as delimiter for tokenizers."); |
81 | |
82 | this.delimiter = delimiter; |
83 | setQuoteCharacter(DEFAULT_QUOTE_CHARACTER); |
84 | } |
85 | |
86 | /** |
87 | * Setter for the delimiter character. |
88 | * |
89 | * @param delimiter |
90 | */ |
91 | public void setDelimiter(String delimiter) { |
92 | this.delimiter = delimiter; |
93 | } |
94 | |
95 | /** |
96 | * The fields to include in the output by position (starting at 0). By |
97 | * default all fields are included, but this property can be set to pick out |
98 | * only a few fields from a larger set. Note that if field names are |
99 | * provided, their number must match the number of included fields. |
100 | * |
101 | * @param includedFields the included fields to set |
102 | */ |
103 | public void setIncludedFields(int[] includedFields) { |
104 | this.includedFields = new HashSet<Integer>(); |
105 | for (int i : includedFields) { |
106 | this.includedFields.add(i); |
107 | } |
108 | } |
109 | |
110 | /** |
111 | * Public setter for the quoteCharacter. The quote character can be used to |
112 | * extend a field across line endings or to enclose a String which contains |
113 | * the delimiter. Inside a quoted token the quote character can be used to |
114 | * escape itself, thus "a""b""c" is tokenized to a"b"c. |
115 | * |
116 | * @param quoteCharacter the quoteCharacter to set |
117 | * |
118 | * @see #DEFAULT_QUOTE_CHARACTER |
119 | */ |
120 | public void setQuoteCharacter(char quoteCharacter) { |
121 | this.quoteCharacter = quoteCharacter; |
122 | this.quoteString = "" + quoteCharacter; |
123 | } |
124 | |
125 | /** |
126 | * Yields the tokens resulting from the splitting of the supplied |
127 | * <code>line</code>. |
128 | * |
129 | * @param line the line to be tokenized |
130 | * |
131 | * @return the resulting tokens |
132 | */ |
133 | @Override |
134 | protected List<String> doTokenize(String line) { |
135 | |
136 | List<String> tokens = new ArrayList<String>(); |
137 | |
138 | // line is never null in current implementation |
139 | // line is checked in parent: AbstractLineTokenizer.tokenize() |
140 | char[] chars = line.toCharArray(); |
141 | boolean inQuoted = false; |
142 | int lastCut = 0; |
143 | int length = chars.length; |
144 | int fieldCount = 0; |
145 | int endIndexLastDelimiter = -1; |
146 | |
147 | for (int i = 0; i < length; i++) { |
148 | char currentChar = chars[i]; |
149 | boolean isEnd = (i == (length - 1)); |
150 | |
151 | boolean isDelimiter = isDelimiter(chars, i, delimiter, endIndexLastDelimiter); |
152 | |
153 | if ((isDelimiter && !inQuoted) || isEnd) { |
154 | endIndexLastDelimiter = i; |
155 | int endPosition = (isEnd ? (length - lastCut) : (i - lastCut)); |
156 | |
157 | if (isEnd && isDelimiter) { |
158 | endPosition = endPosition - delimiter.length(); |
159 | } |
160 | else if (!isEnd){ |
161 | endPosition = (endPosition - delimiter.length()) + 1; |
162 | } |
163 | |
164 | if (includedFields == null || includedFields.contains(fieldCount)) { |
165 | String value = maybeStripQuotes(new String(chars, lastCut, endPosition)); |
166 | tokens.add(value); |
167 | } |
168 | |
169 | fieldCount++; |
170 | |
171 | if (isEnd && (isDelimiter)) { |
172 | if (includedFields == null || includedFields.contains(fieldCount)) { |
173 | tokens.add(""); |
174 | } |
175 | fieldCount++; |
176 | } |
177 | |
178 | lastCut = i + 1; |
179 | } |
180 | else if (isQuoteCharacter(currentChar)) { |
181 | inQuoted = !inQuoted; |
182 | } |
183 | |
184 | } |
185 | |
186 | return tokens; |
187 | } |
188 | |
189 | /** |
190 | * If the string is quoted strip (possibly with whitespace outside the |
191 | * quotes (which will be stripped), replace escaped quotes inside the |
192 | * string. Quotes are escaped with double instances of the quote character. |
193 | * |
194 | * @param string |
195 | * @return the same string but stripped and unescaped if necessary |
196 | */ |
197 | private String maybeStripQuotes(String string) { |
198 | String value = string.trim(); |
199 | if (isQuoted(value)) { |
200 | value = StringUtils.replace(value, "" + quoteCharacter + quoteCharacter, "" + quoteCharacter); |
201 | int endLength = value.length() - 1; |
202 | // used to deal with empty quoted values |
203 | if (endLength == 0) { |
204 | endLength = 1; |
205 | } |
206 | value = value.substring(1, endLength); |
207 | return value; |
208 | } |
209 | return string; |
210 | } |
211 | |
212 | /** |
213 | * Is this string surrounded by quote characters? |
214 | * |
215 | * @param value |
216 | * @return true if the value starts and ends with the |
217 | * {@link #quoteCharacter} |
218 | */ |
219 | private boolean isQuoted(String value) { |
220 | if (value.startsWith(quoteString) && value.endsWith(quoteString)) { |
221 | return true; |
222 | } |
223 | return false; |
224 | } |
225 | |
226 | /** |
227 | * Is the supplied character the delimiter character? |
228 | * |
229 | * @param chars the character array to be checked |
230 | * @return <code>true</code> if the supplied character is the delimiter |
231 | * character |
232 | * @see DelimitedLineTokenizer#DelimitedLineTokenizer(String) |
233 | */ |
234 | private boolean isDelimiter(char[] chars, int i, String token, int endIndexLastDelimiter) { |
235 | boolean result = false; |
236 | |
237 | if(i-endIndexLastDelimiter >= delimiter.length()) { |
238 | if(i >= token.length() - 1) { |
239 | String end = new String(chars, (i-token.length()) + 1, token.length()); |
240 | if(token.equals(end)) { |
241 | result = true; |
242 | } |
243 | } |
244 | } |
245 | |
246 | return result; |
247 | } |
248 | |
249 | /** |
250 | * Is the supplied character a quote character? |
251 | * |
252 | * @param c the character to be checked |
253 | * @return <code>true</code> if the supplied character is an quote character |
254 | * @see #setQuoteCharacter(char) |
255 | */ |
256 | protected boolean isQuoteCharacter(char c) { |
257 | return c == quoteCharacter; |
258 | } |
259 | } |