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1
55 package org.apache.avalon.framework.component;
56
57 import java.util.HashMap  ;
58 import java.util.Map ;
59
60
72 public class DefaultComponentSelector
73 implements ComponentSelector
74 {
75 private final HashMap m_components = new HashMap ();
76 private boolean m_readOnly;
77
78
86 public Component select( Object hint )
87 throws ComponentException
88 {
89 final Component component = (Component)m_components.get( hint );
90
91 if( null != component )
92 {
93 return component;
94 }
95 else
96 {
97 throw new ComponentException( hint.toString(), "Unable to provide implementation." );
98 }
99 }
100
101
106 public boolean hasComponent( final Object hint )
107 {
108 boolean componentExists = false;
109
110 try
111 {
112 this.release( this.select( hint ) );
113 componentExists = true;
114 }
115 catch( Throwable t )
116 {
117 }
119
120 return componentExists;
121 }
122
123
128 public void release( final Component component )
129 {
130 }
133
134
139 public void put( final Object hint, final Component component )
140 {
141 checkWriteable();
142 m_components.put( hint, component );
143 }
144
145
150 protected final Map getComponentMap()
151 {
152 return m_components;
153 }
154
155
158 public void makeReadOnly()
159 {
160 m_readOnly = true;
161 }
162
163
168 protected final void checkWriteable()
169 throws IllegalStateException
170 {
171 if( m_readOnly )
172 {
173 throw new IllegalStateException
174 ( "ComponentSelector is read only and can not be modified" );
175 }
176 }
177 }
178 |
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