Encode a URI path : URI « Network « Java Tutorial

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// 
// Copyright 2004-2005 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at 
// http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// 

/**
 * URI Holder. This class assists with the decoding and encoding or HTTP URI's.
 * It differs from the java.net.URL class as it does not provide communications
 * ability, but it does assist with query string formatting.
 * <P>
 * UTF-8 encoding is used by default for % encoded characters. This may be
 * overridden with the org.mortbay.util.URI.charset system property.
 * 
 * @see UrlEncoded
 * @author Greg Wilkins (gregw)
 */
public class Utils {
  /* ------------------------------------------------------------ */
  /**
   * Encode a URI path.
   * 
   * @param path
   *          The path the encode
   * @param buf
   *          StringBuffer to encode path into (or null)
   * @return The StringBuffer or null if no substitutions required.
   */
  public static StringBuffer encodePath(StringBuffer buf, String path) {
    if (buf == null) {
      loop: for (int i = 0; i < path.length(); i++) {
        char c = path.charAt(i);
        switch (c) {
        case '%':
        case '?':
        case ';':
        case '#':
        case ' ':
          buf = new StringBuffer(path.length() << 1);
          break loop;
        }
      }
      if (buf == null)
        return null;
    }

    synchronized (buf) {
      for (int i = 0; i < path.length(); i++) {
        char c = path.charAt(i);
        switch (c) {
        case '%':
          buf.append("%25");
          continue;
        case '?':
          buf.append("%3F");
          continue;
        case ';':
          buf.append("%3B");
          continue;
        case '#':
          buf.append("%23");
          continue;
        case ' ':
          buf.append("%20");
          continue;
        default:
          buf.append(c);
          continue;
        }
      }
    }

    return buf;
  }
}