001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.util;
019
020import org.apache.commons.lang3.StringUtils;
021import org.apache.yetus.audience.InterfaceAudience;
022
023/**
024 * Utility for Strings.
025 */
026@InterfaceAudience.Private
027public final class Strings {
028  public static final String DEFAULT_SEPARATOR = "=";
029  public static final String DEFAULT_KEYVALUE_SEPARATOR = ", ";
030
031  private Strings() {
032  }
033
034  /**
035   * Append to a StringBuilder a key/value. Uses default separators.
036   * @param sb    StringBuilder to use
037   * @param key   Key to append.
038   * @param value Value to append.
039   * @return Passed <code>sb</code> populated with key/value.
040   */
041  public static StringBuilder appendKeyValue(final StringBuilder sb, final String key,
042    final Object value) {
043    return appendKeyValue(sb, key, value, DEFAULT_SEPARATOR, DEFAULT_KEYVALUE_SEPARATOR);
044  }
045
046  /**
047   * Append to a StringBuilder a key/value. Uses default separators.
048   * @param sb                StringBuilder to use
049   * @param key               Key to append.
050   * @param value             Value to append.
051   * @param separator         Value to use between key and value.
052   * @param keyValueSeparator Value to use between key/value sets.
053   * @return Passed <code>sb</code> populated with key/value.
054   */
055  public static StringBuilder appendKeyValue(final StringBuilder sb, final String key,
056    final Object value, final String separator, final String keyValueSeparator) {
057    if (sb.length() > 0) {
058      sb.append(keyValueSeparator);
059    }
060    return sb.append(key).append(separator).append(value);
061  }
062
063  /**
064   * Given a PTR string generated via reverse DNS lookup, return everything except the trailing
065   * period. Example for host.example.com., return host.example.com
066   * @param dnPtr a domain name pointer (PTR) string.
067   * @return Sanitized hostname with last period stripped off.
068   */
069  public static String domainNamePointerToHostName(String dnPtr) {
070    if (dnPtr == null) {
071      return null;
072    }
073
074    return dnPtr.endsWith(".") ? dnPtr.substring(0, dnPtr.length() - 1) : dnPtr;
075  }
076
077  /**
078   * Push the input string to the right by appending a character before it, usually a space.
079   * @param input   the string to pad
080   * @param padding the character to repeat to the left of the input string
081   * @param length  the desired total length including the padding
082   * @return padding characters + input
083   */
084  public static String padFront(String input, char padding, int length) {
085    if (input.length() > length) {
086      throw new IllegalArgumentException("input \"" + input + "\" longer than maxLength=" + length);
087    }
088    int numPaddingCharacters = length - input.length();
089    return StringUtils.repeat(padding, numPaddingCharacters) + input;
090  }
091}