Java String Encode encode(String s)

Description

encode

License

Open Source License

Declaration

public static String encode(String s) 

Method Source Code

//package com.java2s;
/*//w  w  w . j a  v  a2  s.  c  o m
 * Copyright 2000-2013 Enonic AS
 * http://www.enonic.com/license
 */

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.util.BitSet;

public class Main {
    private static BitSet dontNeedEncoding;
    private final static int caseDiff = ('a' - 'A');

    public static String encode(String s) {

        boolean needToChange = false;
        boolean wroteUnencodedChar = false;
        int maxBytesPerChar = 10; // rather arbitrary limit, but safe for now
        StringBuffer out = new StringBuffer(s.length());
        ByteArrayOutputStream buf = new ByteArrayOutputStream(maxBytesPerChar);
        OutputStreamWriter writer;
        try {
            writer = new OutputStreamWriter(buf, "UTF-8");
        } catch (UnsupportedEncodingException uee) {
            return null;
        }
        for (int i = 0; i < s.length(); i++) {
            int c = (int) s.charAt(i);
            if (dontNeedEncoding.get(c)) {
                if (c == ' ') {
                    c = '+';
                    needToChange = true;
                }
                out.append((char) c);
                wroteUnencodedChar = true;
            } else {
                // convert to external encoding before hex conversion
                try {
                    if (wroteUnencodedChar) { // Fix for 4407610
                        writer = new OutputStreamWriter(buf, "UTF-8");
                        wroteUnencodedChar = false;
                    }
                    writer.write(c);
                    /*
                     * If this character represents the start of a Unicode
                     * surrogate pair, then pass in two characters. It's not
                     * clear what should be done if a bytes reserved in the
                     * surrogate pairs range occurs outside of a legal surrogate
                     * pair. For now, just treat it as if it were any other
                     * character.
                     */
                    if (c >= 0xD800 && c <= 0xDBFF) {
                        /*
                         * (Integer.toHexString(c) + " is high
                         * surrogate");
                         */
                        if ((i + 1) < s.length()) {
                            int d = (int) s.charAt(i + 1);
                            /*
                             * ("\tExamining " +
                             * Integer.toHexString(d));
                             */
                            if (d >= 0xDC00 && d <= 0xDFFF) {
                                /*
                                 * ("\t" +
                                 * Integer.toHexString(d) + " is low
                                 * surrogate");
                                 */
                                writer.write(d);
                                i++;
                            }
                        }
                    }
                    writer.flush();
                } catch (IOException e) {
                    buf.reset();
                    continue;
                }
                byte[] bufferBytes = buf.toByteArray();
                for (byte bufferByte : bufferBytes) {
                    out.append('%');
                    char ch = Character.forDigit((bufferByte >> 4) & 0xF, 16);
                    // converting to use uppercase letter as part of
                    // the hex value if ch is a letter.
                    if (Character.isLetter(ch)) {
                        ch -= caseDiff;
                    }
                    out.append(ch);
                    ch = Character.forDigit(bufferByte & 0xF, 16);
                    if (Character.isLetter(ch)) {
                        ch -= caseDiff;
                    }
                    out.append(ch);
                }
                buf.reset();
                needToChange = true;
            }
        }

        return (needToChange ? out.toString() : s);
    }
}

Related

1. encode(final String source, final String encoding, BitSet notEncoded)
2. encode(String data, String encode)
3. encode(String encoding, String string)
4. encode(String encoding, String text)
5. encode(String name)
6. encode(String s)
7. encode(String s)
8. encode(String s, String enc)
9. encode(String s, String encoding)