Package org.apache.commons.lang

Class StringEscapeUtils

java.lang.Object
org.apache.commons.lang.StringEscapeUtils
public class StringEscapeUtils extends Object

Escapes and unescapes Strings for Java, Java Script, HTML, XML, and SQL.

#ThreadSafe#

Since:
2.0
Version:
$Id: StringEscapeUtils.java 1057072 2011-01-10 01:55:57Z niallp $

  • Field Details

    • CSV_DELIMITER

      private static final char CSV_DELIMITER
      See Also:

    • CSV_QUOTE

      private static final char CSV_QUOTE
      See Also:

    • CSV_QUOTE_STR

      private static final String CSV_QUOTE_STR

    • CSV_SEARCH_CHARS

      private static final char[] CSV_SEARCH_CHARS

  • Constructor Details

    • 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 Details

    • escapeJava

      public static String escapeJava(String str)

      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 must be escaped.

      Example: 

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

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

    • escapeJava

      public static void escapeJava(Writer out, String str) throws IOException

      Escapes the characters in a String using Java String rules to a Writer.

      A null string input has no effect.

      Parameters:
      out - Writer to write escaped string into
      str - String to escape values in, may be null
      Throws:
      IllegalArgumentException - if the Writer is null
      IOException - if error occurs on underlying Writer
      See Also:

    • escapeJavaScript

      public static String escapeJavaScript(String str)

      Escapes the characters in a String using JavaScript String rules.

      Escapes any values it finds into their JavaScript 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 JavaScript strings is that in JavaScript, a single quote must be escaped.

      Example: 

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

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

    • escapeJavaScript

      public static void escapeJavaScript(Writer out, String str) throws IOException

      Escapes the characters in a String using JavaScript String rules to a Writer.

      A null string input has no effect.

      Parameters:
      out - Writer to write escaped string into
      str - String to escape values in, may be null
      Throws:
      IllegalArgumentException - if the Writer is null
      IOException - if error occurs on underlying Writer
      See Also:

    • escapeJavaStyleString

      private static String escapeJavaStyleString(String str, boolean escapeSingleQuotes, boolean escapeForwardSlash)

      Worker method for the escapeJavaScript(String) method.

      Parameters:
      str - String to escape values in, may be null
      escapeSingleQuotes - escapes single quotes if true
      escapeForwardSlash - TODO
      Returns:
      the escaped string

    • escapeJavaStyleString

      private static void escapeJavaStyleString(Writer out, String str, boolean escapeSingleQuote, boolean escapeForwardSlash) throws IOException

      Worker method for the escapeJavaScript(String) method.

      Parameters:
      out - write to receieve the escaped string
      str - String to escape values in, may be null
      escapeSingleQuote - escapes single quotes if true
      escapeForwardSlash - TODO
      Throws:
      IOException - if an IOException occurs

    • hex

      private static String hex(char ch)

      Returns an upper case hexadecimal String for the given character.

      Parameters:
      ch - The character to convert.
      Returns:
      An upper case hexadecimal String

    • unescapeJava

      public static String unescapeJava(String str)

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

    • unescapeJava

      public static void unescapeJava(Writer out, String str) throws IOException

      Unescapes any Java literals found in the String to a Writer.

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

      A null string input has no effect.

      Parameters:
      out - the Writer used to output unescaped characters
      str - the String to unescape, may be null
      Throws:
      IllegalArgumentException - if the Writer is null
      IOException - if error occurs on underlying Writer

    • unescapeJavaScript

      public static String unescapeJavaScript(String str)

      Unescapes any JavaScript 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:
      str - the String to unescape, may be null
      Returns:
      A new unescaped String, null if null string input
      See Also:

    • unescapeJavaScript

      public static void unescapeJavaScript(Writer out, String str) throws IOException

      Unescapes any JavaScript literals found in the String to a Writer.

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

      A null string input has no effect.

      Parameters:
      out - the Writer used to output unescaped characters
      str - the String to unescape, may be null
      Throws:
      IllegalArgumentException - if the Writer is null
      IOException - if error occurs on underlying Writer
      See Also:

    • escapeHtml

      public static String escapeHtml(String str)

      Escapes the characters in a String using HTML entities.

      For example:

      "bread" & "butter"

      becomes:

      "bread" & "butter".

      Supports all known HTML 4.0 entities, including funky accents. Note that the commonly used apostrophe escape character (') is not a legal entity and so is not supported).

      Parameters:
      str - the String to escape, may be null
      Returns:
      a new escaped String, null if null string input
      See Also:

    • escapeHtml

      public static void escapeHtml(Writer writer, String string) throws IOException

      Escapes the characters in a String using HTML entities and writes them to a Writer.

      For example:

      "bread" & "butter"

      becomes:

      "bread" & "butter".

      Supports all known HTML 4.0 entities, including funky accents. Note that the commonly used apostrophe escape character (') is not a legal entity and so is not supported).

      Parameters:
      writer - the writer receiving the escaped string, not null
      string - the String to escape, may be null
      Throws:
      IllegalArgumentException - if the writer is null
      IOException - when Writer passed throws the exception from calls to the Writer.write(int) methods.
      See Also:

    • unescapeHtml

      public static String unescapeHtml(String str)

      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:
      str - the String to unescape, may be null
      Returns:
      a new unescaped String, null if null string input
      See Also:

    • unescapeHtml

      public static void unescapeHtml(Writer writer, String string) throws IOException

      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:
      writer - the writer receiving the unescaped string, not null
      string - the String to unescape, may be null
      Throws:
      IllegalArgumentException - if the writer is null
      IOException - if an IOException occurs
      See Also:

    • escapeXml

      public static void escapeXml(Writer writer, String str) throws IOException

      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 currently escaped to their numerical \\u equivalent. This may change in future releases.

      Parameters:
      writer - the writer receiving the unescaped string, not null
      str - the String to escape, may be null
      Throws:
      IllegalArgumentException - if the writer is null
      IOException - if there is a problem writing
      See Also:

    • escapeXml

      public static String escapeXml(String str)

      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 currently escaped to their numerical \\u equivalent. This may change in future releases.

      Parameters:
      str - the String to escape, may be null
      Returns:
      a new escaped String, null if null string input
      See Also:

    • unescapeXml

      public static void unescapeXml(Writer writer, String str) throws IOException

      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:
      writer - the writer receiving the unescaped string, not null
      str - the String to unescape, may be null
      Throws:
      IllegalArgumentException - if the writer is null
      IOException - if there is a problem writing
      See Also:

    • unescapeXml

      public static String unescapeXml(String str)

      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:
      str - the String to unescape, may be null
      Returns:
      a new unescaped String, null if null string input
      See Also:

    • escapeSql

      public static String escapeSql(String str)

      Escapes the characters in a String to be suitable to pass to an SQL query.

      For example, 

      statement.executeQuery("SELECT * FROM MOVIES WHERE TITLE='" + 
   StringEscapeUtils.escapeSql("McHale's Navy") + 
   "'");

      At present, this method only turns single-quotes into doubled single-quotes ("McHale's Navy" => "McHale''s Navy"). It does not handle the cases of percent (%) or underscore (_) for use in LIKE clauses.

      see http://www.jguru.com/faq/view.jsp?EID=8881
      Parameters:
      str - the string to escape, may be null
      Returns:
      a new String, escaped for SQL, null if null string input

    • escapeCsv

      public static String escapeCsv(String str)

      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:
      str - 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

    • escapeCsv

      public static void escapeCsv(Writer out, String str) throws IOException

      Writes 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 written 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 written unchanged (null values are ignored).

      see Wikipedia and RFC 4180.
      Parameters:
      str - the input CSV column String, may be null
      out - Writer to write input string to, enclosed in double quotes if it contains a comma, newline or double quote
      Throws:
      IOException - if error occurs on underlying Writer
      Since:
      2.4

    • unescapeCsv

      public static String unescapeCsv(String str)

      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:
      str - 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

    • unescapeCsv

      public static void unescapeCsv(Writer out, String str) throws IOException

      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:
      str - the input CSV column String, may be null
      out - Writer to write the input String to, with enclosing double quotes removed and embedded double quotes unescaped, null if null string input
      Throws:
      IOException - if error occurs on underlying Writer
      Since:
      2.4