Class ParameterMap

java/org/apache/catalina/util/ParameterMap.java:37–276

Implementation of java.util.Map that includes a locked property. This class can be used to safely expose Catalina internal parameter map objects to user classes without having to clone them in order to avoid modifications. When first created, a ParameterMap

 * @param <V> The type of Value
 */
public final class ParameterMap<K, V> implements Map<K,V>, Serializable {

    @Serial
    private static final long serialVersionUID = 2L;

    /** The underlying map to which operations are delegated. */
    private final Map<K,V> delegatedMap;

    /** An unmodifiable view of the delegated map. */
    private final Map<K,V> unmodifiableDelegatedMap;


    /**
     * Construct a new, empty map with the default initial capacity and load factor.
     */
    public ParameterMap() {
        delegatedMap = new LinkedHashMap<>();
        unmodifiableDelegatedMap = Collections.unmodifiableMap(delegatedMap);
    }


    /**
     * Construct a new, empty map with the specified initial capacity and default load factor.
     *
     * @param initialCapacity The initial capacity of this map
     */
    public ParameterMap(int initialCapacity) {
        delegatedMap = new LinkedHashMap<>(initialCapacity);
        unmodifiableDelegatedMap = Collections.unmodifiableMap(delegatedMap);
    }


    /**
     * Construct a new, empty map with the specified initial capacity and load factor.
     *
     * @param initialCapacity The initial capacity of this map
     * @param loadFactor      The load factor of this map
     */
    public ParameterMap(int initialCapacity, float loadFactor) {
        delegatedMap = new LinkedHashMap<>(initialCapacity, loadFactor);
        unmodifiableDelegatedMap = Collections.unmodifiableMap(delegatedMap);
    }


    /**
     * Construct a new map with the same mappings as the given map.
     *
     * @param map Map whose contents are duplicated in the new map
     */
    public ParameterMap(Map<K,V> map) {
        // Unroll loop for performance - https://bz.apache.org/bugzilla/show_bug.cgi?id=69820
        int mapSize = map.size();
        delegatedMap = new LinkedHashMap<>((int) (mapSize * 1.5));
        for (Map.Entry<K,V> entry : map.entrySet()) {
            delegatedMap.put(entry.getKey(), entry.getValue());
        }
        unmodifiableDelegatedMap = Collections.unmodifiableMap(delegatedMap);
    }