Coverage Report - org.apache.commons.lang3.text.StrLookup
 
Classes in this File Line Coverage Branch Coverage Complexity
StrLookup
90%
19/21
75%
3/4
2
StrLookup$MapStrLookup
100%
9/9
100%
4/4
2
 
 1  
 /*
 2  
  * Licensed to the Apache Software Foundation (ASF) under one or more
 3  
  * contributor license agreements.  See the NOTICE file distributed with
 4  
  * this work for additional information regarding copyright ownership.
 5  
  * The ASF licenses this file to You under the Apache License, Version 2.0
 6  
  * (the "License"); you may not use this file except in compliance with
 7  
  * the License.  You may obtain a copy of the License at
 8  
  *
 9  
  *      http://www.apache.org/licenses/LICENSE-2.0
 10  
  *
 11  
  * Unless required by applicable law or agreed to in writing, software
 12  
  * distributed under the License is distributed on an "AS IS" BASIS,
 13  
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 14  
  * See the License for the specific language governing permissions and
 15  
  * limitations under the License.
 16  
  */
 17  
 package org.apache.commons.lang3.text;
 18  
 
 19  
 import java.util.Enumeration;
 20  
 import java.util.Map;
 21  
 import java.util.Properties;
 22  
 
 23  
 /**
 24  
  * Lookup a String key to a String value.
 25  
  * <p>
 26  
  * This class represents the simplest form of a string to string map.
 27  
  * It has a benefit over a map in that it can create the result on
 28  
  * demand based on the key.
 29  
  * <p>
 30  
  * This class comes complete with various factory methods.
 31  
  * If these do not suffice, you can subclass and implement your own matcher.
 32  
  * <p>
 33  
  * For example, it would be possible to implement a lookup that used the
 34  
  * key as a primary key, and looked up the value on demand from the database
 35  
  *
 36  
  * @since 2.2
 37  
  * @version $Id: StrLookup.java 1654144 2015-01-23 08:47:00Z britter $
 38  
  */
 39  
 public abstract class StrLookup<V> {
 40  
 
 41  
     /**
 42  
      * Lookup that always returns null.
 43  
      */
 44  1
     private static final StrLookup<String> NONE_LOOKUP = new MapStrLookup<String>(null);
 45  
 
 46  
     //-----------------------------------------------------------------------
 47  
     /**
 48  
      * Returns a lookup which always returns null.
 49  
      *
 50  
      * @return a lookup that always returns null, not null
 51  
      */
 52  
     public static StrLookup<?> noneLookup() {
 53  3
         return NONE_LOOKUP;
 54  
     }
 55  
 
 56  
     /**
 57  
      * Creates a copy of the given properties instance.
 58  
      * 
 59  
      * @param input the Properties instance to copy.
 60  
      * @return a copy of {@code input}.
 61  
      */
 62  
     private static Properties copyProperties(Properties input) {
 63  8
         if (input == null) {
 64  0
             return null;
 65  
         }
 66  
 
 67  8
         Properties output = new Properties();
 68  
         @SuppressWarnings("unchecked") // Property names are Strings.
 69  8
         Enumeration<String> propertyNames = (Enumeration<String>) input.propertyNames();
 70  
 
 71  483
         while (propertyNames.hasMoreElements()) {
 72  475
             String propertyName = propertyNames.nextElement();
 73  475
             output.setProperty(propertyName, input.getProperty(propertyName));
 74  475
         }
 75  
 
 76  8
         return output;
 77  
     }
 78  
 
 79  
     /**
 80  
      * Returns a new lookup which uses a copy of the current
 81  
      * {@link System#getProperties() System properties}.
 82  
      * <p>
 83  
      * If a security manager blocked access to system properties, then null will
 84  
      * be returned from every lookup.
 85  
      * <p>
 86  
      * If a null key is used, this lookup will throw a NullPointerException.
 87  
      *
 88  
      * @return a lookup using system properties, not null
 89  
      */
 90  
     public static StrLookup<String> systemPropertiesLookup() {
 91  8
         Properties systemProperties = null;
 92  
 
 93  
         try {
 94  8
             systemProperties = System.getProperties();
 95  0
         } catch (final SecurityException ex) {
 96  
             // Squelched.  All lookup(String) will return null.
 97  8
         }
 98  
 
 99  8
         Properties properties = copyProperties(systemProperties);
 100  
         @SuppressWarnings("unchecked") // System property keys and values are always Strings
 101  8
         final Map<String, String> propertiesMap = (Map) properties;
 102  
 
 103  8
         return new MapStrLookup<String>(propertiesMap);
 104  
     }
 105  
 
 106  
     /**
 107  
      * Returns a lookup which looks up values using a map.
 108  
      * <p>
 109  
      * If the map is null, then null will be returned from every lookup.
 110  
      * The map result object is converted to a string using toString().
 111  
      *
 112  
      * @param <V> the type of the values supported by the lookup
 113  
      * @param map  the map of keys to values, may be null
 114  
      * @return a lookup using the map, not null
 115  
      */
 116  
     public static <V> StrLookup<V> mapLookup(final Map<String, V> map) {
 117  69
         return new MapStrLookup<V>(map);
 118  
     }
 119  
 
 120  
     //-----------------------------------------------------------------------
 121  
     /**
 122  
      * Constructor.
 123  
      */
 124  
     protected StrLookup() {
 125  78
         super();
 126  78
     }
 127  
 
 128  
     /**
 129  
      * Looks up a String key to a String value.
 130  
      * <p>
 131  
      * The internal implementation may use any mechanism to return the value.
 132  
      * The simplest implementation is to use a Map. However, virtually any
 133  
      * implementation is possible.
 134  
      * <p>
 135  
      * For example, it would be possible to implement a lookup that used the
 136  
      * key as a primary key, and looked up the value on demand from the database
 137  
      * Or, a numeric based implementation could be created that treats the key
 138  
      * as an integer, increments the value and return the result as a string -
 139  
      * converting 1 to 2, 15 to 16 etc.
 140  
      * <p>
 141  
      * The {@link #lookup(String)} method always returns a String, regardless of
 142  
      * the underlying data, by converting it as necessary. For example:
 143  
      * <pre>
 144  
      * Map&lt;String, Object&gt; map = new HashMap&lt;String, Object&gt;();
 145  
      * map.put("number", Integer.valueOf(2));
 146  
      * assertEquals("2", StrLookup.mapLookup(map).lookup("number"));
 147  
      * </pre>
 148  
      * @param key  the key to be looked up, may be null
 149  
      * @return the matching value, null if no match
 150  
      */
 151  
     public abstract String lookup(String key);
 152  
 
 153  
     //-----------------------------------------------------------------------
 154  
     /**
 155  
      * Lookup implementation that uses a Map.
 156  
      */
 157  
     static class MapStrLookup<V> extends StrLookup<V> {
 158  
 
 159  
         /** Map keys are variable names and value. */
 160  
         private final Map<String, V> map;
 161  
 
 162  
         /**
 163  
          * Creates a new instance backed by a Map.
 164  
          *
 165  
          * @param map  the map of keys to values, may be null
 166  
          */
 167  78
         MapStrLookup(final Map<String, V> map) {
 168  78
             this.map = map;
 169  78
         }
 170  
 
 171  
         /**
 172  
          * Looks up a String key to a String value using the map.
 173  
          * <p>
 174  
          * If the map is null, then null is returned.
 175  
          * The map result object is converted to a string using toString().
 176  
          *
 177  
          * @param key  the key to be looked up, may be null
 178  
          * @return the matching value, null if no match
 179  
          */
 180  
         @Override
 181  
         public String lookup(final String key) {
 182  800
             if (map == null) {
 183  6
                 return null;
 184  
             }
 185  794
             final Object obj = map.get(key);
 186  793
             if (obj == null) {
 187  178
                 return null;
 188  
             }
 189  615
             return obj.toString();
 190  
         }
 191  
     }
 192  
 }