org.apache.commons.lang3

## Class StringEscapeUtils

- java.lang.Object
- - org.apache.commons.lang3.StringEscapeUtils

-     public class StringEscapeUtils
      extends Object

  Escapes and unescapes `String`s for Java, Java Script, HTML and XML.

  #ThreadSafe#

  Since:
    2.0
  Version:
    $Id: StringEscapeUtils.java 1467206 2013-04-12 08:39:02Z bayard $

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static CharSequenceTranslator` | `ESCAPE_CSV` Translator object for escaping individual Comma Separated Values.
    `static CharSequenceTranslator` | `ESCAPE_ECMASCRIPT` Translator object for escaping EcmaScript/JavaScript.
    `static CharSequenceTranslator` | `ESCAPE_HTML3` Translator object for escaping HTML version 3.0.
    `static CharSequenceTranslator` | `ESCAPE_HTML4` Translator object for escaping HTML version 4.0.
    `static CharSequenceTranslator` | `ESCAPE_JAVA` Translator object for escaping Java.
    `static CharSequenceTranslator` | `ESCAPE_JSON` Translator object for escaping Json.
    `static CharSequenceTranslator` | `ESCAPE_XML` Translator object for escaping XML.
    `static CharSequenceTranslator` | `UNESCAPE_CSV` Translator object for unescaping escaped Comma Separated Value entries.
    `static CharSequenceTranslator` | `UNESCAPE_ECMASCRIPT` Translator object for unescaping escaped EcmaScript.
    `static CharSequenceTranslator` | `UNESCAPE_HTML3` Translator object for unescaping escaped HTML 3.0.
    `static CharSequenceTranslator` | `UNESCAPE_HTML4` Translator object for unescaping escaped HTML 4.0.
    `static CharSequenceTranslator` | `UNESCAPE_JAVA` Translator object for unescaping escaped Java.
    `static CharSequenceTranslator` | `UNESCAPE_JSON` Translator object for unescaping escaped Json.
    `static CharSequenceTranslator` | `UNESCAPE_XML` Translator object for unescaping escaped XML.

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `StringEscapeUtils()` `StringEscapeUtils` instances should NOT be constructed in standard programming.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `static String` | `escapeCsv(String input)` Returns a `String` value for a CSV column enclosed in double quotes, if required.
    `static String` | `escapeEcmaScript(String input)` Escapes the characters in a `String` using EcmaScript String rules.
    `static String` | `escapeHtml3(String input)` Escapes the characters in a `String` using HTML entities.
    `static String` | `escapeHtml4(String input)` Escapes the characters in a `String` using HTML entities.
    `static String` | `escapeJava(String input)` Escapes the characters in a `String` using Java String rules.
    `static String` | `escapeJson(String input)` Escapes the characters in a `String` using Json String rules.
    `static String` | `escapeXml(String input)` Escapes the characters in a `String` using XML entities.
    `static String` | `unescapeCsv(String input)` Returns a `String` value for an unescaped CSV column.
    `static String` | `unescapeEcmaScript(String input)` Unescapes any EcmaScript literals found in the `String`.
    `static String` | `unescapeHtml3(String input)` Unescapes a string containing entity escapes to a string containing the actual Unicode characters corresponding to the escapes.
    `static String` | `unescapeHtml4(String input)` Unescapes a string containing entity escapes to a string containing the actual Unicode characters corresponding to the escapes.
    `static String` | `unescapeJava(String input)` Unescapes any Java literals found in the `String`.
    `static String` | `unescapeJson(String input)` Unescapes any Json literals found in the `String`.
    `static String` | `unescapeXml(String input)` Unescapes a string containing XML entity escapes to a string containing the actual Unicode characters corresponding to the escapes.

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Field Detail

    - #### ESCAPE_JAVA

          public static final CharSequenceTranslator ESCAPE_JAVA

      Translator object for escaping Java. While `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

    - #### ESCAPE_ECMASCRIPT

          public static final CharSequenceTranslator ESCAPE_ECMASCRIPT

      Translator object for escaping EcmaScript/JavaScript. While `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

    - #### ESCAPE_JSON

          public static final CharSequenceTranslator ESCAPE_JSON

      Translator object for escaping Json. While `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

    - #### ESCAPE_XML

          public static final CharSequenceTranslator ESCAPE_XML

      Translator object for escaping XML. While `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

    - #### ESCAPE_HTML3

          public static final CharSequenceTranslator ESCAPE_HTML3

      Translator object for escaping HTML version 3.0. While `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

    - #### ESCAPE_HTML4

          public static final CharSequenceTranslator ESCAPE_HTML4

      Translator object for escaping HTML version 4.0. While `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

    - #### ESCAPE_CSV

          public static final CharSequenceTranslator ESCAPE_CSV

      Translator object for escaping individual Comma Separated Values. While `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

    - #### UNESCAPE_JAVA

          public static final CharSequenceTranslator UNESCAPE_JAVA

      Translator object for unescaping escaped Java. While `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

    - #### UNESCAPE_ECMASCRIPT

          public static final CharSequenceTranslator UNESCAPE_ECMASCRIPT

      Translator object for unescaping escaped EcmaScript. While `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

    - #### UNESCAPE_JSON

          public static final CharSequenceTranslator UNESCAPE_JSON

      Translator object for unescaping escaped Json. While `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

    - #### UNESCAPE_HTML3

          public static final CharSequenceTranslator UNESCAPE_HTML3

      Translator object for unescaping escaped HTML 3.0. While `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

    - #### UNESCAPE_HTML4

          public static final CharSequenceTranslator UNESCAPE_HTML4

      Translator object for unescaping escaped HTML 4.0. While `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

    - #### UNESCAPE_XML

          public static final CharSequenceTranslator UNESCAPE_XML

      Translator object for unescaping escaped XML. While `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

    - #### UNESCAPE_CSV

          public static final CharSequenceTranslator UNESCAPE_CSV

      Translator object for unescaping escaped Comma Separated Value entries. While `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

  - ### Constructor Detail

    - #### StringEscapeUtils

          public StringEscapeUtils()

      `StringEscapeUtils` instances should NOT be constructed in standard programming.

      Instead, the class should be used as:

          StringEscapeUtils.escapeJava("foo");

      This constructor is public to permit tools that require a JavaBean instance to operate.

  - ### Method Detail

    - #### escapeJava

          public static final String escapeJava(String input)

      Escapes the characters in a `String` using Java String rules.

      Deals correctly with quotes and control-chars (tab, backslash, cr, ff, etc.)

      So a tab becomes the characters `'\\'` and `'t'`.

      The only difference between Java strings and JavaScript strings is that in JavaScript, a single quote and forward-slash (/) are escaped.

      Example:

           input string: He didn't say, "Stop!"
           output string: He didn't say, \"Stop!\"

      Parameters:
        `input` - String to escape values in, may be null
      Returns:
        String with escaped values, `null` if null string input

    - #### escapeEcmaScript

          public static final String escapeEcmaScript(String input)

      Escapes the characters in a `String` using EcmaScript String rules.

      Escapes any values it finds into their EcmaScript String form. Deals correctly with quotes and control-chars (tab, backslash, cr, ff, etc.)

      So a tab becomes the characters `'\\'` and `'t'`.

      The only difference between Java strings and EcmaScript strings is that in EcmaScript, a single quote and forward-slash (/) are escaped.

      Note that EcmaScript is best known by the JavaScript and ActionScript dialects.

      Example:

           input string: He didn't say, "Stop!"
           output string: He didn\'t say, \"Stop!\"

      Parameters:
        `input` - String to escape values in, may be null
      Returns:
        String with escaped values, `null` if null string input
      Since:
        3.0

    - #### escapeJson

          public static final String escapeJson(String input)

      Escapes the characters in a `String` using Json String rules.

      Escapes any values it finds into their Json String form. Deals correctly with quotes and control-chars (tab, backslash, cr, ff, etc.)

      So a tab becomes the characters `'\\'` and `'t'`.

      The only difference between Java strings and Json strings is that in Json, forward-slash (/) is escaped.

      See http://www.ietf.org/rfc/rfc4627.txt for further details.

      Example:

           input string: He didn't say, "Stop!"
           output string: He didn't say, \"Stop!\"

      Parameters:
        `input` - String to escape values in, may be null
      Returns:
        String with escaped values, `null` if null string input
      Since:
        3.2

    - #### unescapeJava

          public static final String unescapeJava(String input)

      Unescapes any Java literals found in the `String`. For example, it will turn a sequence of `'\'` and `'n'` into a newline character, unless the `'\'` is preceded by another `'\'`.

      Parameters:
        `input` - the `String` to unescape, may be null
      Returns:
        a new unescaped `String`, `null` if null string input

    - #### unescapeEcmaScript

          public static final String unescapeEcmaScript(String input)

      Unescapes any EcmaScript literals found in the `String`.

      For example, it will turn a sequence of `'\'` and `'n'` into a newline character, unless the `'\'` is preceded by another `'\'`.

      Parameters:
        `input` - the `String` to unescape, may be null
      Returns:
        A new unescaped `String`, `null` if null string input
      Since:
        3.0
      See Also:
        `unescapeJava(String)`

    - #### unescapeJson

          public static final String unescapeJson(String input)

      Unescapes any Json literals found in the `String`.

      For example, it will turn a sequence of `'\'` and `'n'` into a newline character, unless the `'\'` is preceded by another `'\'`.

      Parameters:
        `input` - the `String` to unescape, may be null
      Returns:
        A new unescaped `String`, `null` if null string input
      Since:
        3.2
      See Also:
        `unescapeJava(String)`

    - #### escapeHtml4

          public static final String escapeHtml4(String input)

      Escapes the characters in a `String` using HTML entities.

      For example:

      `"bread" & "butter"`

      becomes:

      `&quot;bread&quot; &amp; &quot;butter&quot;`.

      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).

      Parameters:
        `input` - the `String` to escape, may be null
      Returns:
        a new escaped `String`, `null` if null string input
      Since:
        3.0
      See Also:
        ISO Entities, HTML 3.2 Character Entities for ISO Latin-1, HTML 4.0 Character entity references, HTML 4.01 Character References, HTML 4.01 Code positions

    - #### escapeHtml3

          public static final String escapeHtml3(String input)

      Escapes the characters in a `String` using HTML entities.

      Supports only the HTML 3.0 entities.

      Parameters:
        `input` - the `String` to escape, may be null
      Returns:
        a new escaped `String`, `null` if null string input
      Since:
        3.0

    - #### unescapeHtml4

          public static final String unescapeHtml4(String input)

      Unescapes a string containing entity escapes to a string containing the actual Unicode characters corresponding to the escapes. Supports HTML 4.0 entities.

      For example, the string "&lt;Fran&ccedil;ais&gt;" will become "<Français>"

      If an entity is unrecognized, it is left alone, and inserted verbatim into the result string. e.g. "&gt;&zzzz;x" will become ">&zzzz;x".

      Parameters:
        `input` - the `String` to unescape, may be null
      Returns:
        a new unescaped `String`, `null` if null string input
      Since:
        3.0

    - #### unescapeHtml3

          public static final String unescapeHtml3(String input)

      Unescapes a string containing entity escapes to a string containing the actual Unicode characters corresponding to the escapes. Supports only HTML 3.0 entities.

      Parameters:
        `input` - the `String` to unescape, may be null
      Returns:
        a new unescaped `String`, `null` if null string input
      Since:
        3.0

    - #### escapeXml

          public static final String escapeXml(String input)

      Escapes the characters in a `String` using XML entities.

      For example: `"bread" & "butter"` => `&quot;bread&quot; &amp; &quot;butter&quot;`.

      Supports only the five basic XML entities (gt, lt, quot, amp, apos). Does not support DTDs or external entities.

      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: `StringEscapeUtils.ESCAPE_XML.with( NumericEntityEscaper.between(0x7f, Integer.MAX_VALUE) );`

      Parameters:
        `input` - the `String` to escape, may be null
      Returns:
        a new escaped `String`, `null` if null string input
      See Also:
        `unescapeXml(java.lang.String)`

    - #### unescapeXml

          public static final String unescapeXml(String input)

      Unescapes a string containing XML entity escapes to a string containing the actual Unicode characters corresponding to the escapes.

      Supports only the five basic XML entities (gt, lt, quot, amp, apos). Does not support DTDs or external entities.

      Note that numerical \\u Unicode codes are unescaped to their respective Unicode characters. This may change in future releases.

      Parameters:
        `input` - the `String` to unescape, may be null
      Returns:
        a new unescaped `String`, `null` if null string input
      See Also:
        `escapeXml(String)`

    - #### escapeCsv

          public static final String escapeCsv(String input)

      Returns a `String` value for a CSV column enclosed in double quotes, if required.

      If the value contains a comma, newline or double quote, then the String value is returned enclosed in double quotes.

      Any double quote characters in the value are escaped with another double quote.

      If the value does not contain a comma, newline or double quote, then the String value is returned unchanged.

      see Wikipedia and RFC 4180.
      Parameters:
        `input` - the input CSV column String, may be null
      Returns:
        the input String, enclosed in double quotes if the value contains a comma, newline or double quote, `null` if null string input
      Since:
        2.4

    - #### unescapeCsv

          public static final String unescapeCsv(String input)

      Returns a `String` value for an unescaped CSV column.

      If the value is enclosed in double quotes, and contains a comma, newline or double quote, then quotes are removed.

      Any double quote escaped characters (a pair of double quotes) are unescaped to just one double quote.

      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.

      see Wikipedia and RFC 4180.
      Parameters:
        `input` - the input CSV column String, may be null
      Returns:
        the input String, with enclosing double quotes removed and embedded double quotes unescaped, `null` if null string input
      Since:
        2.4

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