ZkUtilies.java

/**
 * Copyright 2014 Comcast Cable Communications Management, LLC
 *
 * 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.
 */
package com.comcast.viper.flume2storm.zookeeper;

import org.apache.commons.lang.StringUtils;
import org.apache.zookeeper.common.PathUtils;

import com.google.common.base.Preconditions;

/**
 * Utilies for ZkClient
 */
public class ZkUtilies {
  protected static final Character SEPARATOR_CHAR = '/';
  protected static final String SEPARATOR = SEPARATOR_CHAR.toString();

  /**
   * Builds a valid (guaranteed) ZNode path made of the components passed in
   * parameter. This method handles the path separator between component, so it
   * can be called with or without them.
   * 
   * @param components
   *          A bunch of ZNode path elements. Some may be null.
   * @return The concatenated path of all the elements
   * @throws IllegalArgumentException
   *           if the path is invalid (empty for example)
   */
  public static String buildZkPath(final String... components) {
    Preconditions.checkArgument(components != null, "No path element specified");
    boolean isFirst = true;
    final StringBuilder result = new StringBuilder();
    for (int i = 0; i < components.length; i++) {
      if (StringUtils.isEmpty(components[i])) {
        continue;
      }
      assert components[i] != null;
      // Checking path separator
      if (isFirst) {
        // First element must start with /
        if (!components[i].startsWith(SEPARATOR)) {
          result.append(SEPARATOR);
        }
        result.append(components[i]);
      } else {
        if (!SEPARATOR_CHAR.equals(result.charAt(result.length() - 1)) && !components[i].startsWith(SEPARATOR)) {
          result.append(SEPARATOR);
          result.append(components[i]);
        } else if (SEPARATOR_CHAR.equals(result.charAt(result.length() - 1)) && components[i].startsWith(SEPARATOR)) {
          result.append(components[i].substring(1));
        } else {
          result.append(components[i]);
        }
      }
      isFirst = false;
    }
    final String path = result.toString();
    PathUtils.validatePath(path);
    return path;
  }
}