hbase-common/src/main/java/org/apache/hadoop/hbase/util/Strings.java

   1 /**
   2  *
   3  * Licensed to the Apache Software Foundation (ASF) under one
   4  * or more contributor license agreements.  See the NOTICE file
   5  * distributed with this work for additional information
   6  * regarding copyright ownership.  The ASF licenses this file
   7  * to you under the Apache License, Version 2.0 (the
   8  * "License"); you may not use this file except in compliance
   9  * with the License.  You may obtain a copy of the License at
  10  *
  11  *     http://www.apache.org/licenses/LICENSE-2.0
  12  *
  13  * Unless required by applicable law or agreed to in writing, software
  14  * distributed under the License is distributed on an "AS IS" BASIS,
  15  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  16  * See the License for the specific language governing permissions and
  17  * limitations under the License.
  18  */
  19 package org.apache.hadoop.hbase.util;
  20
  21 import org.apache.commons.lang3.StringUtils;
  22 import org.apache.yetus.audience.InterfaceAudience;
  23
  24 /**
  25  * Utility for Strings.
  26  */
  27 @InterfaceAudience.Private
  28 public final class Strings {
  29   public static final String DEFAULT_SEPARATOR = "=";
  30   public static final String DEFAULT_KEYVALUE_SEPARATOR = ", ";
  31
  32   private Strings() {
  33   }
  34
  35   /**
  36    * Append to a StringBuilder a key/value.
  37    * Uses default separators.
  38    * @param sb StringBuilder to use
  39    * @param key Key to append.
  40    * @param value Value to append.
  41    * @return Passed <code>sb</code> populated with key/value.
  42    */
  43   public static StringBuilder appendKeyValue(final StringBuilder sb,
  44       final String key, final Object value) {
  45     return appendKeyValue(sb, key, value, DEFAULT_SEPARATOR,
  46       DEFAULT_KEYVALUE_SEPARATOR);
  47   }
  48
  49   /**
  50    * Append to a StringBuilder a key/value.
  51    * Uses default separators.
  52    * @param sb StringBuilder to use
  53    * @param key Key to append.
  54    * @param value Value to append.
  55    * @param separator Value to use between key and value.
  56    * @param keyValueSeparator Value to use between key/value sets.
  57    * @return Passed <code>sb</code> populated with key/value.
  58    */
  59   public static StringBuilder appendKeyValue(final StringBuilder sb,
  60       final String key, final Object value, final String separator,
  61       final String keyValueSeparator) {
  62     if (sb.length() > 0) {
  63       sb.append(keyValueSeparator);
  64     }
  65     return sb.append(key).append(separator).append(value);
  66   }
  67
  68   /**
  69    * Given a PTR string generated via reverse DNS lookup, return everything
  70    * except the trailing period. Example for host.example.com., return
  71    * host.example.com
  72    * @param dnPtr a domain name pointer (PTR) string.
  73    * @return Sanitized hostname with last period stripped off.
  74    */
  75   public static String domainNamePointerToHostName(String dnPtr) {
  76     if (dnPtr == null) {
  77       return null;
  78     }
  79
  80     return dnPtr.endsWith(".") ? dnPtr.substring(0, dnPtr.length()-1) : dnPtr;
  81   }
  82
  83   /**
  84    * Push the input string to the right by appending a character before it, usually a space.
  85    * @param input the string to pad
  86    * @param padding the character to repeat to the left of the input string
  87    * @param length the desired total length including the padding
  88    * @return padding characters + input
  89    */
  90   public static String padFront(String input, char padding, int length) {
  91     if (input.length() > length) {
  92       throw new IllegalArgumentException("input \"" + input + "\" longer than maxLength=" + length);
  93     }
  94     int numPaddingCharacters = length - input.length();
  95     return StringUtils.repeat(padding, numPaddingCharacters) + input;
  96   }
  97 }