Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.commons.lang3; import java.io.IOException; import java.io.Writer; import org.apache.commons.lang3.text.translate.AggregateTranslator; import org.apache.commons.lang3.text.translate.CharSequenceTranslator; import org.apache.commons.lang3.text.translate.EntityArrays; import org.apache.commons.lang3.text.translate.JavaUnicodeEscaper; import org.apache.commons.lang3.text.translate.LookupTranslator; import org.apache.commons.lang3.text.translate.NumericEntityEscaper; import org.apache.commons.lang3.text.translate.NumericEntityUnescaper; import org.apache.commons.lang3.text.translate.OctalUnescaper; import org.apache.commons.lang3.text.translate.UnicodeUnescaper; import org.apache.commons.lang3.text.translate.UnicodeUnpairedSurrogateRemover; /** * <p>Escapes and unescapes {@code String}s for * Java, Java Script, HTML and XML.</p> * * <p>#ThreadSafe#</p> * @since 2.0 * @version $Id$ */ public class StringEscapeUtils { /* ESCAPE TRANSLATORS */ /** * Translator object for escaping Java. * * While {@link #escapeJava(String)} is the expected method of use, this * object allows the Java escaping functionality to be used * as the foundation for a custom translator. * * @since 3.0 */ public static final CharSequenceTranslator ESCAPE_JAVA = new LookupTranslator( new String[][] { { "\"", "\\\"" }, { "\\", "\\\\" }, }) .with(new LookupTranslator(EntityArrays.JAVA_CTRL_CHARS_ESCAPE())) .with(JavaUnicodeEscaper.outsideOf(32, 0x7f)); /** * Translator object for escaping EcmaScript/JavaScript. * * While {@link #escapeEcmaScript(String)} is the expected method of use, this * object allows the EcmaScript escaping functionality to be used * as the foundation for a custom translator. * * @since 3.0 */ public static final CharSequenceTranslator ESCAPE_ECMASCRIPT = new AggregateTranslator( new LookupTranslator( new String[][] { { "'", "\\'" }, { "\"", "\\\"" }, { "\\", "\\\\" }, { "/", "\\/" } }), new LookupTranslator(EntityArrays.JAVA_CTRL_CHARS_ESCAPE()), JavaUnicodeEscaper.outsideOf(32, 0x7f)); /** * Translator object for escaping Json. * * While {@link #escapeJson(String)} is the expected method of use, this * object allows the Json escaping functionality to be used * as the foundation for a custom translator. * * @since 3.2 */ public static final CharSequenceTranslator ESCAPE_JSON = new AggregateTranslator( new LookupTranslator(new String[][] { { "\"", "\\\"" }, { "\\", "\\\\" }, { "/", "\\/" } }), new LookupTranslator(EntityArrays.JAVA_CTRL_CHARS_ESCAPE()), JavaUnicodeEscaper.outsideOf(32, 0x7f)); /** * Translator object for escaping XML. * * While {@link #escapeXml(String)} is the expected method of use, this * object allows the XML escaping functionality to be used * as the foundation for a custom translator. * * @since 3.0 * @deprecated use {@link #ESCAPE_XML10} or {@link #ESCAPE_XML11} instead. */ @Deprecated public static final CharSequenceTranslator ESCAPE_XML = new AggregateTranslator( new LookupTranslator(EntityArrays.BASIC_ESCAPE()), new LookupTranslator(EntityArrays.APOS_ESCAPE())); /** * Translator object for escaping XML 1.0. * * While {@link #escapeXml10(String)} is the expected method of use, this * object allows the XML escaping functionality to be used * as the foundation for a custom translator. * * @since 3.3 */ public static final CharSequenceTranslator ESCAPE_XML10 = new AggregateTranslator( new LookupTranslator(EntityArrays.BASIC_ESCAPE()), new LookupTranslator(EntityArrays.APOS_ESCAPE()), new LookupTranslator(new String[][] { { "\u0000", "" }, { "\u0001", "" }, { "\u0002", "" }, { "\u0003", "" }, { "\u0004", "" }, { "\u0005", "" }, { "\u0006", "" }, { "\u0007", "" }, { "\u0008", "" }, { "\u000b", "" }, { "\u000c", "" }, { "\u000e", "" }, { "\u000f", "" }, { "\u0010", "" }, { "\u0011", "" }, { "\u0012", "" }, { "\u0013", "" }, { "\u0014", "" }, { "\u0015", "" }, { "\u0016", "" }, { "\u0017", "" }, { "\u0018", "" }, { "\u0019", "" }, { "\u001a", "" }, { "\u001b", "" }, { "\u001c", "" }, { "\u001d", "" }, { "\u001e", "" }, { "\u001f", "" }, { "\ufffe", "" }, { "\uffff", "" } }), NumericEntityEscaper.between(0x7f, 0x84), NumericEntityEscaper.between(0x86, 0x9f), new UnicodeUnpairedSurrogateRemover()); /** * Translator object for escaping XML 1.1. * * While {@link #escapeXml11(String)} is the expected method of use, this * object allows the XML escaping functionality to be used * as the foundation for a custom translator. * * @since 3.3 */ public static final CharSequenceTranslator ESCAPE_XML11 = new AggregateTranslator( new LookupTranslator(EntityArrays.BASIC_ESCAPE()), new LookupTranslator(EntityArrays.APOS_ESCAPE()), new LookupTranslator(new String[][] { { "\u0000", "" }, { "\u000b", "" }, { "\u000c", "" }, { "\ufffe", "" }, { "\uffff", "" } }), NumericEntityEscaper.between(0x1, 0x8), NumericEntityEscaper.between(0xe, 0x1f), NumericEntityEscaper.between(0x7f, 0x84), NumericEntityEscaper.between(0x86, 0x9f), new UnicodeUnpairedSurrogateRemover()); /** * Translator object for escaping HTML version 3.0. * * While {@link #escapeHtml3(String)} is the expected method of use, this * object allows the HTML escaping functionality to be used * as the foundation for a custom translator. * * @since 3.0 */ public static final CharSequenceTranslator ESCAPE_HTML3 = new AggregateTranslator( new LookupTranslator(EntityArrays.BASIC_ESCAPE()), new LookupTranslator(EntityArrays.ISO8859_1_ESCAPE())); /** * Translator object for escaping HTML version 4.0. * * While {@link #escapeHtml4(String)} is the expected method of use, this * object allows the HTML escaping functionality to be used * as the foundation for a custom translator. * * @since 3.0 */ public static final CharSequenceTranslator ESCAPE_HTML4 = new AggregateTranslator( new LookupTranslator(EntityArrays.BASIC_ESCAPE()), new LookupTranslator(EntityArrays.ISO8859_1_ESCAPE()), new LookupTranslator(EntityArrays.HTML40_EXTENDED_ESCAPE())); /** * Translator object for escaping individual Comma Separated Values. * * While {@link #escapeCsv(String)} is the expected method of use, this * object allows the CSV escaping functionality to be used * as the foundation for a custom translator. * * @since 3.0 */ public static final CharSequenceTranslator ESCAPE_CSV = new CsvEscaper(); // TODO: Create a parent class - 'SinglePassTranslator' ? // It would handle the index checking + length returning, // and could also have an optimization check method. static class CsvEscaper extends CharSequenceTranslator { private static final char CSV_DELIMITER = ','; private static final char CSV_QUOTE = '"'; private static final String CSV_QUOTE_STR = String.valueOf(CSV_QUOTE); private static final char[] CSV_SEARCH_CHARS = new char[] { CSV_DELIMITER, CSV_QUOTE, CharUtils.CR, CharUtils.LF }; @Override public int translate(final CharSequence input, final int index, final Writer out) throws IOException { if (index != 0) { throw new IllegalStateException("CsvEscaper should never reach the [1] index"); } if (StringUtils.containsNone(input.toString(), CSV_SEARCH_CHARS)) { out.write(input.toString()); } else { out.write(CSV_QUOTE); out.write(StringUtils.replace(input.toString(), CSV_QUOTE_STR, CSV_QUOTE_STR + CSV_QUOTE_STR)); out.write(CSV_QUOTE); } return Character.codePointCount(input, 0, input.length()); } } /* UNESCAPE TRANSLATORS */ /** * Translator object for unescaping escaped Java. * * While {@link #unescapeJava(String)} is the expected method of use, this * object allows the Java unescaping functionality to be used * as the foundation for a custom translator. * * @since 3.0 */ // TODO: throw "illegal character: \92" as an Exception if a \ on the end of the Java (as per the compiler)? public static final CharSequenceTranslator UNESCAPE_JAVA = new AggregateTranslator(new OctalUnescaper(), // .between('\1', '\377'), new UnicodeUnescaper(), new LookupTranslator(EntityArrays.JAVA_CTRL_CHARS_UNESCAPE()), new LookupTranslator( new String[][] { { "\\\\", "\\" }, { "\\\"", "\"" }, { "\\'", "'" }, { "\\", "" } })); /** * Translator object for unescaping escaped EcmaScript. * * While {@link #unescapeEcmaScript(String)} is the expected method of use, this * object allows the EcmaScript unescaping functionality to be used * as the foundation for a custom translator. * * @since 3.0 */ public static final CharSequenceTranslator UNESCAPE_ECMASCRIPT = UNESCAPE_JAVA; /** * Translator object for unescaping escaped Json. * * While {@link #unescapeJson(String)} is the expected method of use, this * object allows the Json unescaping functionality to be used * as the foundation for a custom translator. * * @since 3.2 */ public static final CharSequenceTranslator UNESCAPE_JSON = UNESCAPE_JAVA; /** * Translator object for unescaping escaped HTML 3.0. * * While {@link #unescapeHtml3(String)} is the expected method of use, this * object allows the HTML unescaping functionality to be used * as the foundation for a custom translator. * * @since 3.0 */ public static final CharSequenceTranslator UNESCAPE_HTML3 = new AggregateTranslator( new LookupTranslator(EntityArrays.BASIC_UNESCAPE()), new LookupTranslator(EntityArrays.ISO8859_1_UNESCAPE()), new NumericEntityUnescaper()); /** * Translator object for unescaping escaped HTML 4.0. * * While {@link #unescapeHtml4(String)} is the expected method of use, this * object allows the HTML unescaping functionality to be used * as the foundation for a custom translator. * * @since 3.0 */ public static final CharSequenceTranslator UNESCAPE_HTML4 = new AggregateTranslator( new LookupTranslator(EntityArrays.BASIC_UNESCAPE()), new LookupTranslator(EntityArrays.ISO8859_1_UNESCAPE()), new LookupTranslator(EntityArrays.HTML40_EXTENDED_UNESCAPE()), new NumericEntityUnescaper()); /** * Translator object for unescaping escaped XML. * * While {@link #unescapeXml(String)} is the expected method of use, this * object allows the XML unescaping functionality to be used * as the foundation for a custom translator. * * @since 3.0 */ public static final CharSequenceTranslator UNESCAPE_XML = new AggregateTranslator( new LookupTranslator(EntityArrays.BASIC_UNESCAPE()), new LookupTranslator(EntityArrays.APOS_UNESCAPE()), new NumericEntityUnescaper()); /** * Translator object for unescaping escaped Comma Separated Value entries. * * While {@link #unescapeCsv(String)} is the expected method of use, this * object allows the CSV unescaping functionality to be used * as the foundation for a custom translator. * * @since 3.0 */ public static final CharSequenceTranslator UNESCAPE_CSV = new CsvUnescaper(); static class CsvUnescaper extends CharSequenceTranslator { private static final char CSV_DELIMITER = ','; private static final char CSV_QUOTE = '"'; private static final String CSV_QUOTE_STR = String.valueOf(CSV_QUOTE); private static final char[] CSV_SEARCH_CHARS = new char[] { CSV_DELIMITER, CSV_QUOTE, CharUtils.CR, CharUtils.LF }; @Override public int translate(final CharSequence input, final int index, final Writer out) throws IOException { if (index != 0) { throw new IllegalStateException("CsvUnescaper should never reach the [1] index"); } if (input.charAt(0) != CSV_QUOTE || input.charAt(input.length() - 1) != CSV_QUOTE) { out.write(input.toString()); return Character.codePointCount(input, 0, input.length()); } // strip quotes final String quoteless = input.subSequence(1, input.length() - 1).toString(); if (StringUtils.containsAny(quoteless, CSV_SEARCH_CHARS)) { // deal with escaped quotes; ie) "" out.write(StringUtils.replace(quoteless, CSV_QUOTE_STR + CSV_QUOTE_STR, CSV_QUOTE_STR)); } else { out.write(input.toString()); } return Character.codePointCount(input, 0, input.length()); } } /* Helper functions */ /** * <p>{@code StringEscapeUtils} instances should NOT be constructed in * standard programming.</p> * * <p>Instead, the class should be used as:</p> * <pre>StringEscapeUtils.escapeJava("foo");</pre> * * <p>This constructor is public to permit tools that require a JavaBean * instance to operate.</p> */ public StringEscapeUtils() { super(); } // Java and JavaScript //-------------------------------------------------------------------------- /** * <p>Escapes the characters in a {@code String} using Java String rules.</p> * * <p>Deals correctly with quotes and control-chars (tab, backslash, cr, ff, etc.) </p> * * <p>So a tab becomes the characters {@code '\\'} and * {@code 't'}.</p> * * <p>The only difference between Java strings and JavaScript strings * is that in JavaScript, a single quote and forward-slash (/) are escaped.</p> * * <p>Example:</p> * <pre> * input string: He didn't say, "Stop!" * output string: He didn't say, \"Stop!\" * </pre> * * @param input String to escape values in, may be null * @return String with escaped values, {@code null} if null string input */ public static final String escapeJava(final String input) { return ESCAPE_JAVA.translate(input); } /** * <p>Escapes the characters in a {@code String} using EcmaScript String rules.</p> * <p>Escapes any values it finds into their EcmaScript String form. * Deals correctly with quotes and control-chars (tab, backslash, cr, ff, etc.) </p> * * <p>So a tab becomes the characters {@code '\\'} and * {@code 't'}.</p> * * <p>The only difference between Java strings and EcmaScript strings * is that in EcmaScript, a single quote and forward-slash (/) are escaped.</p> * * <p>Note that EcmaScript is best known by the JavaScript and ActionScript dialects. </p> * * <p>Example:</p> * <pre> * input string: He didn't say, "Stop!" * output string: He didn\'t say, \"Stop!\" * </pre> * * @param input String to escape values in, may be null * @return String with escaped values, {@code null} if null string input * * @since 3.0 */ public static final String escapeEcmaScript(final String input) { return ESCAPE_ECMASCRIPT.translate(input); } /** * <p>Escapes the characters in a {@code String} using Json String rules.</p> * <p>Escapes any values it finds into their Json String form. * Deals correctly with quotes and control-chars (tab, backslash, cr, ff, etc.) </p> * * <p>So a tab becomes the characters {@code '\\'} and * {@code 't'}.</p> * * <p>The only difference between Java strings and Json strings * is that in Json, forward-slash (/) is escaped.</p> * * <p>See http://www.ietf.org/rfc/rfc4627.txt for further details. </p> * * <p>Example:</p> * <pre> * input string: He didn't say, "Stop!" * output string: He didn't say, \"Stop!\" * </pre> * * @param input String to escape values in, may be null * @return String with escaped values, {@code null} if null string input * * @since 3.2 */ public static final String escapeJson(final String input) { return ESCAPE_JSON.translate(input); } /** * <p>Unescapes any Java literals found in the {@code String}. * For example, it will turn a sequence of {@code '\'} and * {@code 'n'} into a newline character, unless the {@code '\'} * is preceded by another {@code '\'}.</p> * * @param input the {@code String} to unescape, may be null * @return a new unescaped {@code String}, {@code null} if null string input */ public static final String unescapeJava(final String input) { return UNESCAPE_JAVA.translate(input); } /** * <p>Unescapes any EcmaScript literals found in the {@code String}.</p> * * <p>For example, it will turn a sequence of {@code '\'} and {@code 'n'} * into a newline character, unless the {@code '\'} is preceded by another * {@code '\'}.</p> * * @see #unescapeJava(String) * @param input the {@code String} to unescape, may be null * @return A new unescaped {@code String}, {@code null} if null string input * * @since 3.0 */ public static final String unescapeEcmaScript(final String input) { return UNESCAPE_ECMASCRIPT.translate(input); } /** * <p>Unescapes any Json literals found in the {@code String}.</p> * * <p>For example, it will turn a sequence of {@code '\'} and {@code 'n'} * into a newline character, unless the {@code '\'} is preceded by another * {@code '\'}.</p> * * @see #unescapeJava(String) * @param input the {@code String} to unescape, may be null * @return A new unescaped {@code String}, {@code null} if null string input * * @since 3.2 */ public static final String unescapeJson(final String input) { return UNESCAPE_JSON.translate(input); } // HTML and XML //-------------------------------------------------------------------------- /** * <p>Escapes the characters in a {@code String} using HTML entities.</p> * * <p> * For example: * </p> * <p><code>"bread" & "butter"</code></p> * becomes: * <p> * <code>&quot;bread&quot; &amp; &quot;butter&quot;</code>. * </p> * * <p>Supports all known HTML 4.0 entities, including funky accents. * Note that the commonly used apostrophe escape character (&apos;) * is not a legal entity and so is not supported). </p> * * @param input the {@code String} to escape, may be null * @return a new escaped {@code String}, {@code null} if null string input * * @see <a href="http://hotwired.lycos.com/webmonkey/reference/special_characters/">ISO Entities</a> * @see <a href="http://www.w3.org/TR/REC-html32#latin1">HTML 3.2 Character Entities for ISO Latin-1</a> * @see <a href="http://www.w3.org/TR/REC-html40/sgml/entities.html">HTML 4.0 Character entity references</a> * @see <a href="http://www.w3.org/TR/html401/charset.html#h-5.3">HTML 4.01 Character References</a> * @see <a href="http://www.w3.org/TR/html401/charset.html#code-position">HTML 4.01 Code positions</a> * * @since 3.0 */ public static final String escapeHtml4(final String input) { return ESCAPE_HTML4.translate(input); } /** * <p>Escapes the characters in a {@code String} using HTML entities.</p> * <p>Supports only the HTML 3.0 entities. </p> * * @param input the {@code String} to escape, may be null * @return a new escaped {@code String}, {@code null} if null string input * * @since 3.0 */ public static final String escapeHtml3(final String input) { return ESCAPE_HTML3.translate(input); } //----------------------------------------------------------------------- /** * <p>Unescapes a string containing entity escapes to a string * containing the actual Unicode characters corresponding to the * escapes. Supports HTML 4.0 entities.</p> * * <p>For example, the string {@code "<Français>"} * will become {@code "<Franais>"}</p> * * <p>If an entity is unrecognized, it is left alone, and inserted * verbatim into the result string. e.g. {@code ">&zzzz;x"} will * become {@code ">&zzzz;x"}.</p> * * @param input the {@code String} to unescape, may be null * @return a new unescaped {@code String}, {@code null} if null string input * * @since 3.0 */ public static final String unescapeHtml4(final String input) { return UNESCAPE_HTML4.translate(input); } /** * <p>Unescapes a string containing entity escapes to a string * containing the actual Unicode characters corresponding to the * escapes. Supports only HTML 3.0 entities.</p> * * @param input the {@code String} to unescape, may be null * @return a new unescaped {@code String}, {@code null} if null string input * * @since 3.0 */ public static final String unescapeHtml3(final String input) { return UNESCAPE_HTML3.translate(input); } //----------------------------------------------------------------------- /** * <p>Escapes the characters in a {@code String} using XML entities.</p> * * <p>For example: {@code "bread" & "butter"} => * {@code "bread" & "butter"}. * </p> * * <p>Supports only the five basic XML entities (gt, lt, quot, amp, apos). * Does not support DTDs or external entities.</p> * * <p>Note that Unicode characters greater than 0x7f are as of 3.0, no longer * escaped. If you still wish this functionality, you can achieve it * via the following: * {@code StringEscapeUtils.ESCAPE_XML.with( NumericEntityEscaper.between(0x7f, Integer.MAX_VALUE) );}</p> * * @param input the {@code String} to escape, may be null * @return a new escaped {@code String}, {@code null} if null string input * @see #unescapeXml(java.lang.String) * @deprecated use {@link #escapeXml10(java.lang.String)} or {@link #escapeXml11(java.lang.String)} instead. */ @Deprecated public static final String escapeXml(final String input) { return ESCAPE_XML.translate(input); } /** * <p>Escapes the characters in a {@code String} using XML entities.</p> * * <p>For example: {@code "bread" & "butter"} => * {@code "bread" & "butter"}. * </p> * * <p>Note that XML 1.0 is a text-only format: it cannot represent control * characters or unpaired Unicode surrogate codepoints, even after escaping. * {@code escapeXml10} will remove characters that do not fit in the * following ranges:</p> * * <p>{@code #x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD] | [#x10000-#x10FFFF]}</p> * * <p>Though not strictly necessary, {@code escapeXml10} will escape * characters in the following ranges:</p> * * <p>{@code [#x7F-#x84] | [#x86-#x9F]}</p> * * <p>The returned string can be inserted into a valid XML 1.0 or XML 1.1 * document. If you want to allow more non-text characters in an XML 1.1 * document, use {@link #escapeXml11(String)}.</p> * * @param input the {@code String} to escape, may be null * @return a new escaped {@code String}, {@code null} if null string input * @see #unescapeXml(java.lang.String) * @since 3.3 */ public static String escapeXml10(final String input) { return ESCAPE_XML10.translate(input); } /** * <p>Escapes the characters in a {@code String} using XML entities.</p> * * <p>For example: {@code "bread" & "butter"} => * {@code "bread" & "butter"}. * </p> * * <p>XML 1.1 can represent certain control characters, but it cannot represent * the null byte or unpaired Unicode surrogate codepoints, even after escaping. * {@code escapeXml11} will remove characters that do not fit in the following * ranges:</p> * * <p>{@code [#x1-#xD7FF] | [#xE000-#xFFFD] | [#x10000-#x10FFFF]}</p> * * <p>{@code escapeXml11} will escape characters in the following ranges:</p> * * <p>{@code [#x1-#x8] | [#xB-#xC] | [#xE-#x1F] | [#x7F-#x84] | [#x86-#x9F]}</p> * * <p>The returned string can be inserted into a valid XML 1.1 document. Do not * use it for XML 1.0 documents.</p> * * @param input the {@code String} to escape, may be null * @return a new escaped {@code String}, {@code null} if null string input * @see #unescapeXml(java.lang.String) * @since 3.3 */ public static String escapeXml11(final String input) { return ESCAPE_XML11.translate(input); } //----------------------------------------------------------------------- /** * <p>Unescapes a string containing XML entity escapes to a string * containing the actual Unicode characters corresponding to the * escapes.</p> * * <p>Supports only the five basic XML entities (gt, lt, quot, amp, apos). * Does not support DTDs or external entities.</p> * * <p>Note that numerical \\u Unicode codes are unescaped to their respective * Unicode characters. This may change in future releases. </p> * * @param input the {@code String} to unescape, may be null * @return a new unescaped {@code String}, {@code null} if null string input * @see #escapeXml(String) * @see #escapeXml10(String) * @see #escapeXml11(String) */ public static final String unescapeXml(final String input) { return UNESCAPE_XML.translate(input); } //----------------------------------------------------------------------- /** * <p>Returns a {@code String} value for a CSV column enclosed in double quotes, * if required.</p> * * <p>If the value contains a comma, newline or double quote, then the * String value is returned enclosed in double quotes.</p> * * <p>Any double quote characters in the value are escaped with another double quote.</p> * * <p>If the value does not contain a comma, newline or double quote, then the * String value is returned unchanged.</p> * * see <a href="http://en.wikipedia.org/wiki/Comma-separated_values">Wikipedia</a> and * <a href="http://tools.ietf.org/html/rfc4180">RFC 4180</a>. * * @param input the input CSV column String, may be null * @return the input String, enclosed in double quotes if the value contains a comma, * newline or double quote, {@code null} if null string input * @since 2.4 */ public static final String escapeCsv(final String input) { return ESCAPE_CSV.translate(input); } /** * <p>Returns a {@code String} value for an unescaped CSV column. </p> * * <p>If the value is enclosed in double quotes, and contains a comma, newline * or double quote, then quotes are removed. * </p> * * <p>Any double quote escaped characters (a pair of double quotes) are unescaped * to just one double quote. </p> * * <p>If the value is not enclosed in double quotes, or is and does not contain a * comma, newline or double quote, then the String value is returned unchanged.</p> * * see <a href="http://en.wikipedia.org/wiki/Comma-separated_values">Wikipedia</a> and * <a href="http://tools.ietf.org/html/rfc4180">RFC 4180</a>. * * @param input the input CSV column String, may be null * @return the input String, with enclosing double quotes removed and embedded double * quotes unescaped, {@code null} if null string input * @since 2.4 */ public static final String unescapeCsv(final String input) { return UNESCAPE_CSV.translate(input); } }