Coverage Report - org.apache.commons.lang3.text.StrLookup
 
Classes in this File Line Coverage Branch Coverage Complexity
StrLookup
86%
13/15
N/A
1,571
StrLookup$MapStrLookup
100%
9/9
100%
4/4
1,571
 
 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  
  * @version $Id: StrLookup.java 1583482 2014-03-31 22:54:57Z niallp $
 36  
  */
 37  
 public abstract class StrLookup<V> {
 38  
 
 39  
     /**
 40  
      * Lookup that always returns null.
 41  
      */
 42  
     private static final StrLookup<String> NONE_LOOKUP;
 43  
     /**
 44  
      * Lookup that uses System properties.
 45  
      */
 46  
     private static final StrLookup<String> SYSTEM_PROPERTIES_LOOKUP;
 47  
     static {
 48  1
         NONE_LOOKUP = new MapStrLookup<String>(null);
 49  1
         StrLookup<String> lookup = null;
 50  
         try {
 51  1
             final Map<?, ?> propMap = System.getProperties();
 52  
             @SuppressWarnings("unchecked") // System property keys and values are always Strings
 53  1
             final Map<String, String> properties = (Map<String, String>) propMap;
 54  1
             lookup = new MapStrLookup<String>(properties);
 55  0
         } catch (final SecurityException ex) {
 56  0
             lookup = NONE_LOOKUP;
 57  1
         }
 58  1
         SYSTEM_PROPERTIES_LOOKUP = lookup;
 59  1
     }
 60  
 
 61  
     //-----------------------------------------------------------------------
 62  
     /**
 63  
      * Returns a lookup which always returns null.
 64  
      *
 65  
      * @return a lookup that always returns null, not null
 66  
      */
 67  
     public static StrLookup<?> noneLookup() {
 68  3
         return NONE_LOOKUP;
 69  
     }
 70  
 
 71  
     /**
 72  
      * Returns a lookup which uses {@link System#getProperties() System properties}
 73  
      * to lookup the key to value.
 74  
      * <p>
 75  
      * If a security manager blocked access to system properties, then null will
 76  
      * be returned from every lookup.
 77  
      * <p>
 78  
      * If a null key is used, this lookup will throw a NullPointerException.
 79  
      *
 80  
      * @return a lookup using system properties, not null
 81  
      */
 82  
     public static StrLookup<String> systemPropertiesLookup() {
 83  5
         return SYSTEM_PROPERTIES_LOOKUP;
 84  
     }
 85  
 
 86  
     /**
 87  
      * Returns a lookup which looks up values using a map.
 88  
      * <p>
 89  
      * If the map is null, then null will be returned from every lookup.
 90  
      * The map result object is converted to a string using toString().
 91  
      *
 92  
      * @param <V> the type of the values supported by the lookup
 93  
      * @param map  the map of keys to values, may be null
 94  
      * @return a lookup using the map, not null
 95  
      */
 96  
     public static <V> StrLookup<V> mapLookup(final Map<String, V> map) {
 97  68
         return new MapStrLookup<V>(map);
 98  
     }
 99  
 
 100  
     //-----------------------------------------------------------------------
 101  
     /**
 102  
      * Constructor.
 103  
      */
 104  
     protected StrLookup() {
 105  70
         super();
 106  70
     }
 107  
 
 108  
     /**
 109  
      * Looks up a String key to a String value.
 110  
      * <p>
 111  
      * The internal implementation may use any mechanism to return the value.
 112  
      * The simplest implementation is to use a Map. However, virtually any
 113  
      * implementation is possible.
 114  
      * <p>
 115  
      * For example, it would be possible to implement a lookup that used the
 116  
      * key as a primary key, and looked up the value on demand from the database
 117  
      * Or, a numeric based implementation could be created that treats the key
 118  
      * as an integer, increments the value and return the result as a string -
 119  
      * converting 1 to 2, 15 to 16 etc.
 120  
      * <p>
 121  
      * The {@link #lookup(String)} method always returns a String, regardless of
 122  
      * the underlying data, by converting it as necessary. For example:
 123  
      * <pre>
 124  
      * Map&lt;String, Object&gt; map = new HashMap&lt;String, Object&gt;();
 125  
      * map.put("number", Integer.valueOf(2));
 126  
      * assertEquals("2", StrLookup.mapLookup(map).lookup("number"));
 127  
      * </pre>
 128  
      * @param key  the key to be looked up, may be null
 129  
      * @return the matching value, null if no match
 130  
      */
 131  
     public abstract String lookup(String key);
 132  
 
 133  
     //-----------------------------------------------------------------------
 134  
     /**
 135  
      * Lookup implementation that uses a Map.
 136  
      */
 137  
     static class MapStrLookup<V> extends StrLookup<V> {
 138  
 
 139  
         /** Map keys are variable names and value. */
 140  
         private final Map<String, V> map;
 141  
 
 142  
         /**
 143  
          * Creates a new instance backed by a Map.
 144  
          *
 145  
          * @param map  the map of keys to values, may be null
 146  
          */
 147  70
         MapStrLookup(final Map<String, V> map) {
 148  70
             this.map = map;
 149  70
         }
 150  
 
 151  
         /**
 152  
          * Looks up a String key to a String value using the map.
 153  
          * <p>
 154  
          * If the map is null, then null is returned.
 155  
          * The map result object is converted to a string using toString().
 156  
          *
 157  
          * @param key  the key to be looked up, may be null
 158  
          * @return the matching value, null if no match
 159  
          */
 160  
         @Override
 161  
         public String lookup(final String key) {
 162  795
             if (map == null) {
 163  6
                 return null;
 164  
             }
 165  789
             final Object obj = map.get(key);
 166  788
             if (obj == null) {
 167  178
                 return null;
 168  
             }
 169  610
             return obj.toString();
 170  
         }
 171  
     }
 172  
 }