com.mgnt.utils.StringUnicodeEncoderDecoder Maven / Gradle / Ivy
package com.mgnt.utils;
/**
* This class provides Unicode conversion utility methods that allow to convert a string into Unicode sequence and vice-versa. (See methods
* descriptions for details)
*
* @author Michael Gantman
*/
public class StringUnicodeEncoderDecoder {
private final static String UNICODE_PREFIX = "\\u";
private final static String DELIMITER = "\\\\u";
/**
* This method converts a {@link String} of characters in any language into a String That contains a sequence of Unicode codes corresponding to
* characters in the original String For Example String "Hello" will be converted into a String "\u0048\u0065\u006c\u006c\u006f" Null or empty
* String conversion will return an empty String
*
* @param txt {@link String} that contains a sequence of characters to convert
* @return {@link String} That contains a sequence of unicode codes corresponding to the characters in the original String. Each code will be in
* hexadecimal format preceded by prefix "'backslash' + 'u'" with no spaces between them. The String also will have no leading or trailing
* white spaces
*/
public static String encodeStringToUnicodeSequence(String txt) {
StringBuilder result = new StringBuilder();
if (txt != null && !txt.isEmpty()) {
for (int i = 0; i < txt.length(); i++) {
result.append(convertCodePointToUnicodeString(Character.codePointAt(txt, i)));
if (Character.isHighSurrogate(txt.charAt(i))) {
i++;
}
}
}
return result.toString();
}
/**
* This method converts {@link String} that contains a sequence of Unicode codes onto a String of corresponding characters. For example a String
* "\u0048\u0065\u006c\u006c\u006f" will be converted into String "Hello" by this method. This method performs reverse conversion of the one
* performed by method {@link #encodeStringToUnicodeSequence(String)} I.e. Any textual String converted into sequence if Unicode codes by method
* {@link #encodeStringToUnicodeSequence(String)} may be retrieved back by invoking this method on that Unicode sequence String.
*
* @param unicodeSequence {@link String} That contains sequence of Unicode codes. Each code must be in hexadecimal format and must be preceded by
* "'backslash' + 'u'" prefix. (note that prefix '\U' is not valid). This method allows leading and trailing whitespaces for the whole
* String as well as spaces between codes. Those white spaces will be ignored.
* @return {@link String} That contains sequence of characters that correspond to the respective Unicode codes in the original String
* @throws IllegalArgumentException if input String is in invalid format. For example if any code is not in hexadecimal format or the code is not a valid Unicode code
* (not valid code point).
*/
public static String decodeUnicodeSequenceToString(String unicodeSequence) throws IllegalArgumentException {
StringBuilder result = new StringBuilder();
try {
unicodeSequence = unicodeSequence.trim().substring(UNICODE_PREFIX.length());
for (String codePointStr : unicodeSequence.split(DELIMITER)) {
result.append(Character.toChars(Integer.parseInt(codePointStr.trim(), 16)));
}
} catch (Exception e) {
throw new IllegalArgumentException("Error occurred while converting unicode sequence String to String", e);
}
return result.toString();
}
/**
* This method converts an integer that holds a unicode code value into a String
*
* @param codePoint a unicode code value
* @return {@link String} that starts with prefix "'backslash' + 'u'" that follows with hexadecimal value of an integer. If the hexadecimal value
* of an integer is less then four digits the value is padded with preceding zeros. For example if the integer has value 32 (decimal) it
* will be converted into String "\u0020"
*/
private static String convertCodePointToUnicodeString(int codePoint) {
StringBuilder result = new StringBuilder(UNICODE_PREFIX);
String codePointHexStr = Integer.toHexString(codePoint);
codePointHexStr = codePointHexStr.startsWith("0") ? codePointHexStr.substring(1) : codePointHexStr;
if (codePointHexStr.length() <= 4) {
result.append(getPrecedingZerosStr(codePointHexStr.length()));
}
result.append(codePointHexStr);
return result.toString();
}
/**
* This method receives a length of a String and if it is less then 4 it generates a padding String of zeros that can be appended to the String to
* make it of length 4 I.e. if parameter passed is 1 the returned String will be "000". If the parameter passed is 4 or greater empty String is
* returned.
*
* @param codePointStrLength Length of a String to be padded by preceding zeros to the length of 4
* @return padding String
*/
private static String getPrecedingZerosStr(int codePointStrLength) {
StringBuilder result = new StringBuilder();
for (int i = 0; i < 4 - codePointStrLength; i++) {
result.append("0");
}
return result.toString();
}
}