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 *  the License.  You may obtain a copy of the License at
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 *      http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.tomcat.util.buf;

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.BitSet;

Efficient implementation of a UTF-8 encoder. This class is not thread safe - you need one encoder per thread. The encoder will save and recycle the internal objects, avoiding garbage. You can add extra characters that you want preserved, for example while encoding a URL you can add "/".
Author:Costin Manolache
/** * Efficient implementation of a UTF-8 encoder. * This class is not thread safe - you need one encoder per thread. * The encoder will save and recycle the internal objects, avoiding * garbage. * * You can add extra characters that you want preserved, for example * while encoding a URL you can add "/". * * @author Costin Manolache */
public final class UEncoder { public enum SafeCharsSet { WITH_SLASH("/"), DEFAULT(""); private final BitSet safeChars; private BitSet getSafeChars() { return this.safeChars; } private SafeCharsSet(String additionalSafeChars) { safeChars = initialSafeChars(); for (char c : additionalSafeChars.toCharArray()) { safeChars.set(c); } } } // Not static - the set may differ ( it's better than adding // an extra check for "/", "+", etc private BitSet safeChars=null; private C2BConverter c2b=null; private ByteChunk bb=null; private CharChunk cb=null; private CharChunk output=null;
Create a UEncoder with an unmodifiable safe character set.
Params:
  • safeCharsSet – safe characters for this encoder
/** * Create a UEncoder with an unmodifiable safe character set. * * @param safeCharsSet safe characters for this encoder */
public UEncoder(SafeCharsSet safeCharsSet) { this.safeChars = safeCharsSet.getSafeChars(); }
URL Encode string, using a specified encoding.
Params:
  • s – string to be encoded
  • start – the beginning index, inclusive
  • end – the ending index, exclusive
Throws:
Returns:A new CharChunk contained the URL encoded string
/** * URL Encode string, using a specified encoding. * * @param s string to be encoded * @param start the beginning index, inclusive * @param end the ending index, exclusive * * @return A new CharChunk contained the URL encoded string * * @throws IOException If an I/O error occurs */
public CharChunk encodeURL(String s, int start, int end) throws IOException { if (c2b == null) { bb = new ByteChunk(8); // small enough. cb = new CharChunk(2); // small enough. output = new CharChunk(64); // small enough. c2b = new C2BConverter(StandardCharsets.UTF_8); } else { bb.recycle(); cb.recycle(); output.recycle(); } for (int i = start; i < end; i++) { char c = s.charAt(i); if (safeChars.get(c)) { output.append(c); } else { cb.append(c); c2b.convert(cb, bb); // "surrogate" - UTF is _not_ 16 bit, but 21 !!!! // ( while UCS is 31 ). Amazing... if (c >= 0xD800 && c <= 0xDBFF) { if ((i+1) < end) { char d = s.charAt(i+1); if (d >= 0xDC00 && d <= 0xDFFF) { cb.append(d); c2b.convert(cb, bb); i++; } } } urlEncode(output, bb); cb.recycle(); bb.recycle(); } } return output; } protected void urlEncode(CharChunk out, ByteChunk bb) throws IOException { byte[] bytes = bb.getBuffer(); for (int j = bb.getStart(); j < bb.getEnd(); j++) { out.append('%'); char ch = Character.forDigit((bytes[j] >> 4) & 0xF, 16); out.append(ch); ch = Character.forDigit(bytes[j] & 0xF, 16); out.append(ch); } } // -------------------- Internal implementation -------------------- private static BitSet initialSafeChars() { BitSet initialSafeChars=new BitSet(128); int i; for (i = 'a'; i <= 'z'; i++) { initialSafeChars.set(i); } for (i = 'A'; i <= 'Z'; i++) { initialSafeChars.set(i); } for (i = '0'; i <= '9'; i++) { initialSafeChars.set(i); } //safe initialSafeChars.set('$'); initialSafeChars.set('-'); initialSafeChars.set('_'); initialSafeChars.set('.'); // Dangerous: someone may treat this as " " // RFC1738 does allow it, it's not reserved // initialSafeChars.set('+'); //extra initialSafeChars.set('!'); initialSafeChars.set('*'); initialSafeChars.set('\''); initialSafeChars.set('('); initialSafeChars.set(')'); initialSafeChars.set(','); return initialSafeChars; } }