Java String Decode by Charset unicodeCodePoint2PercentHexString(int codePoint, String charsetName)

Description

Return the percentHexOctets string that represents the given Unicode code point in the given character set or null if the given character set cannot encode the given code point.

License

Open Source License

Parameter

Parameter	Description
codePoint	the given Unicode code point
charsetName	the name of the character set.

Exception

Parameter	Description
IllegalArgumentException	if the code point is not defined or the the character set is not supported.

Return

the percentHexOctets string that represents the given Unicode code point in the given character set.

Declaration

public static String unicodeCodePoint2PercentHexString(int codePoint,
        String charsetName)

Method Source Code

//package com.java2s;

import java.nio.charset.Charset;
import java.nio.charset.CharacterCodingException;
import java.nio.CharBuffer;
import java.nio.ByteBuffer;

public class Main {
    /**//ww w. ja v  a  2  s.  co m
     * Return the percentHexOctets string that represents the given Unicode
     * code point in the given character set or null if the given character
     * set cannot encode the given code point.
     *
     * @param codePoint the given Unicode code point
     * @param charsetName the name of the character set.
     * @return the percentHexOctets string that represents the given Unicode code point in the given character set.
     * @throws IllegalArgumentException if the code point is not defined or the the character set is not supported.
     */
    public static String unicodeCodePoint2PercentHexString(int codePoint,
            String charsetName) {
        if (!Character.isDefined(codePoint))
            throw new IllegalArgumentException(
                    "Not a valid Unicode code point [" + codePoint + "].");
        Charset charset = Charset.availableCharsets().get(charsetName);
        if (charset == null)
            throw new IllegalArgumentException("Unsupported charset ["
                    + charsetName + "].");

        char[] chars = Character.toChars(codePoint);
        ByteBuffer byteBuffer = null;
        try {
            byteBuffer = charset.newEncoder()
                    .encode(CharBuffer.wrap(chars));
        } catch (CharacterCodingException e) {
            // The selected charset cannot encode given code point.
            return null;
        }
        byteBuffer.rewind();
        StringBuilder encodedString = new StringBuilder();
        for (int i = 0; i < byteBuffer.limit(); i++) {
            String asHex = Integer.toHexString(byteBuffer.get() & 0xFF);
            encodedString.append("%")
                    .append(asHex.length() == 1 ? "0" : "").append(asHex);
        }

        return encodedString.toString();
    }
}