Coverage Report - org.apache.commons.lang3.text.StrLookup
 
Classes in this File Line Coverage Branch Coverage Complexity
StrLookup
100%
7/7
N/A
1,875
StrLookup$1
N/A
N/A
1,875
StrLookup$MapStrLookup
100%
9/9
100%
4/4
1,875
StrLookup$SystemPropertiesStrLookup
80%
4/5
100%
2/2
1,875
 
 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.Map;
 20  
 
 21  
 /**
 22  
  * Lookup a String key to a String value.
 23  
  * <p>
 24  
  * This class represents the simplest form of a string to string map.
 25  
  * It has a benefit over a map in that it can create the result on
 26  
  * demand based on the key.
 27  
  * <p>
 28  
  * This class comes complete with various factory methods.
 29  
  * If these do not suffice, you can subclass and implement your own matcher.
 30  
  * <p>
 31  
  * For example, it would be possible to implement a lookup that used the
 32  
  * key as a primary key, and looked up the value on demand from the database
 33  
  *
 34  
  * @since 2.2
 35  
  */
 36  
 public abstract class StrLookup<V> {
 37  
 
 38  
     /**
 39  
      * Lookup that always returns null.
 40  
      */
 41  1
     private static final StrLookup<String> NONE_LOOKUP = new MapStrLookup<String>(null);
 42  
 
 43  
     /**
 44  
      * Lookup based on system properties.
 45  
      */
 46  1
     private static final StrLookup<String> SYSTEM_PROPERTIES_LOOKUP = new SystemPropertiesStrLookup();
 47  
 
 48  
     //-----------------------------------------------------------------------
 49  
     /**
 50  
      * Returns a lookup which always returns null.
 51  
      *
 52  
      * @return a lookup that always returns null, not null
 53  
      */
 54  
     public static StrLookup<?> noneLookup() {
 55  3
         return NONE_LOOKUP;
 56  
     }
 57  
 
 58  
     /**
 59  
      * Returns a new lookup which uses a copy of the current
 60  
      * {@link System#getProperties() System properties}.
 61  
      * <p>
 62  
      * If a security manager blocked access to system properties, then null will
 63  
      * be returned from every lookup.
 64  
      * <p>
 65  
      * If a null key is used, this lookup will throw a NullPointerException.
 66  
      *
 67  
      * @return a lookup using system properties, not null
 68  
      */
 69  
     public static StrLookup<String> systemPropertiesLookup() {
 70  8
         return SYSTEM_PROPERTIES_LOOKUP;
 71  
     }
 72  
 
 73  
     /**
 74  
      * Returns a lookup which looks up values using a map.
 75  
      * <p>
 76  
      * If the map is null, then null will be returned from every lookup.
 77  
      * The map result object is converted to a string using toString().
 78  
      *
 79  
      * @param <V> the type of the values supported by the lookup
 80  
      * @param map  the map of keys to values, may be null
 81  
      * @return a lookup using the map, not null
 82  
      */
 83  
     public static <V> StrLookup<V> mapLookup(final Map<String, V> map) {
 84  70
         return new MapStrLookup<V>(map);
 85  
     }
 86  
 
 87  
     //-----------------------------------------------------------------------
 88  
     /**
 89  
      * Constructor.
 90  
      */
 91  
     protected StrLookup() {
 92  72
         super();
 93  72
     }
 94  
 
 95  
     /**
 96  
      * Looks up a String key to a String value.
 97  
      * <p>
 98  
      * The internal implementation may use any mechanism to return the value.
 99  
      * The simplest implementation is to use a Map. However, virtually any
 100  
      * implementation is possible.
 101  
      * <p>
 102  
      * For example, it would be possible to implement a lookup that used the
 103  
      * key as a primary key, and looked up the value on demand from the database
 104  
      * Or, a numeric based implementation could be created that treats the key
 105  
      * as an integer, increments the value and return the result as a string -
 106  
      * converting 1 to 2, 15 to 16 etc.
 107  
      * <p>
 108  
      * The {@link #lookup(String)} method always returns a String, regardless of
 109  
      * the underlying data, by converting it as necessary. For example:
 110  
      * <pre>
 111  
      * Map&lt;String, Object&gt; map = new HashMap&lt;String, Object&gt;();
 112  
      * map.put("number", Integer.valueOf(2));
 113  
      * assertEquals("2", StrLookup.mapLookup(map).lookup("number"));
 114  
      * </pre>
 115  
      * @param key  the key to be looked up, may be null
 116  
      * @return the matching value, null if no match
 117  
      */
 118  
     public abstract String lookup(String key);
 119  
 
 120  
     //-----------------------------------------------------------------------
 121  
     /**
 122  
      * Lookup implementation that uses a Map.
 123  
      */
 124  
     static class MapStrLookup<V> extends StrLookup<V> {
 125  
 
 126  
         /** Map keys are variable names and value. */
 127  
         private final Map<String, V> map;
 128  
 
 129  
         /**
 130  
          * Creates a new instance backed by a Map.
 131  
          *
 132  
          * @param map  the map of keys to values, may be null
 133  
          */
 134  71
         MapStrLookup(final Map<String, V> map) {
 135  71
             this.map = map;
 136  71
         }
 137  
 
 138  
         /**
 139  
          * Looks up a String key to a String value using the map.
 140  
          * <p>
 141  
          * If the map is null, then null is returned.
 142  
          * The map result object is converted to a string using toString().
 143  
          *
 144  
          * @param key  the key to be looked up, may be null
 145  
          * @return the matching value, null if no match
 146  
          */
 147  
         @Override
 148  
         public String lookup(final String key) {
 149  791
             if (map == null) {
 150  6
                 return null;
 151  
             }
 152  785
             final Object obj = map.get(key);
 153  785
             if (obj == null) {
 154  176
                 return null;
 155  
             }
 156  609
             return obj.toString();
 157  
         }
 158  
     }
 159  
 
 160  
     //-----------------------------------------------------------------------
 161  
     /**
 162  
      * Lookup implementation based on system properties.
 163  
      */
 164  2
     private static class SystemPropertiesStrLookup extends StrLookup<String> {
 165  
         /**
 166  
          * {@inheritDoc} This implementation directly accesses system properties.
 167  
          */
 168  
         @Override
 169  
         public String lookup(String key) {
 170  10
             if (key.length() > 0) {
 171  
                 try {
 172  8
                     return System.getProperty(key);
 173  0
                 } catch (SecurityException scex) {
 174  
                     // Squelched. All lookup(String) will return null.
 175  
                 }
 176  
             }
 177  1
             return null;
 178  
         }
 179  
     }
 180  
 }