twuni · July 27, 2013 07:46 · Jul 27, 2013
diff --git a/URLEncoder.java b/URLEncoder.java
@@ -0,0 +1,106 @@
+import java.nio.CharBuffer;
+import java.util.BitSet;
+
+public class URLEncoder {
+
+	private static final char [] IGNORED_BY_DEFAULT = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789!*()-_'.~".toCharArray();
+	private static final char [] HEX = "0123456789ABCDEF".toCharArray();
+	private static final URLEncoder DEFAULT = new URLEncoder();
+
+	public static CharSequence encode( CharSequence s ) {
+		return getDefaultInstance().encodeURIComponent( s );
+	}
+
+	public static URLEncoder getDefaultInstance() {
+		return DEFAULT;
+	}
+
+	/**
+	 * Convert a number to a character array, using the provided buffer.
+	 * 
+	 * @param number
+	 *            the number to convert
+	 * @param array
+	 *            the buffer in which to store the character representation of the converted number
+	 * @param mapping
+	 *            an array of characters whose index corresponds to the character representing that
+	 *            digit. The length of this array determines in which base the number will be
+	 *            represented in the given array.
+	 * @return the given array, after modification. If the array's length is greater than is
+	 *         necessary, its contents will be right-aligned and left-padded with the mapping for
+	 *         the number zero. For example, the result of
+	 *         {@code itoa( 5, new char[8], "01".toCharArray() )} would be "00000101".
+	 */
+	public static char [] itoa( int number, char [] array, char [] mapping ) {
+		int count = 0;
+		int maximum = array.length - 1;
+		for( int value = number; value > 0; value /= mapping.length ) {
+			int digit = value % mapping.length;
+			value -= digit;
+			array[maximum - count] = mapping[digit];
+			count++;
+		}
+		if( count <= maximum ) {
+			for( int zero = count; zero <= maximum; zero++ ) {
+				array[maximum - zero] = mapping[0];
+			}
+		}
+		return array;
+	}
+
+	public static char [] itoa( int number, int arrayLength, char [] mapping ) {
+		return itoa( number, new char [arrayLength], mapping );
+	}
+
+	public static char [] itoa( int number, int arrayLength, String mapping ) {
+		return itoa( number, arrayLength, mapping.toCharArray() );
+	}
+
+	private final char [] a = new char [2];
+	private final BitSet ignored = new BitSet( 256 );
+
+	public URLEncoder() {
+		this( IGNORED_BY_DEFAULT );
+	}
+
+	/**
+	 * Constructs a new URL encoder that encodes everything except the given characters.
+	 * 
+	 * @param unencodedCharacters
+	 *            an array of characters to ignore when encoding.
+	 */
+	public URLEncoder( char [] unencodedCharacters ) {
+		for( int i = 0; i < unencodedCharacters.length; i++ ) {
+			ignored.set( unencodedCharacters[i] );
+		}
+	}
+
+	public URLEncoder( String unencodedCharacters ) {
+		this( unencodedCharacters.toCharArray() );
+	}
+
+	public CharSequence encodeURIComponent( CharSequence s ) {
+
+		CharBuffer out = CharBuffer.allocate( s.length() * 3 );
+		out.limit( s.length() );
+
+		for( int i = 0; i < s.length(); i++ ) {
+			char c = s.charAt( i );
+			if( ignored.get( c ) ) {
+				out.append( c );
+			} else {
+				out.append( '%' );
+				out.limit( out.limit() + 2 );
+				itoa( c, a, HEX );
+				out.append( a[0] );
+				out.append( a[1] );
+			}
+		}
+
+		out.position( 0 );
+
+		return out;
+
+	}
+
+}