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1
55 package org.apache.avalon.framework.service;
56
57 import java.util.HashMap  ;
58 import java.util.Map ;
59
60
66 public class DefaultServiceSelector
67 implements ServiceSelector
68 {
69 private final HashMap m_objects = new HashMap ();
70 private boolean m_readOnly;
71 private final String m_role;
72
73
76 public DefaultServiceSelector()
77 {
78 this("");
79 }
80
81
88 public DefaultServiceSelector(String role)
89 {
90 if ( null==role )
91 {
92 throw new NullPointerException (role);
93 }
94
95 m_role = role;
96 }
97
98
105 public Object select( Object hint )
106 throws ServiceException
107 {
108 final Object object = m_objects.get( hint );
109
110 if( null != object )
111 {
112 return object;
113 }
114 else
115 {
116 throw new ServiceException( m_role + "/" + hint.toString(), "Unable to provide implementation" );
117 }
118 }
119
120
125 public boolean isSelectable( final Object hint )
126 {
127 boolean objectExists = false;
128
129 try
130 {
131 this.release( this.select( hint ) );
132 objectExists = true;
133 }
134 catch( Throwable t )
135 {
136 }
138
139 return objectExists;
140 }
141
142
147 public void release( final Object object )
148 {
149 }
152
153
158 public void put( final Object hint, final Object object )
159 {
160 checkWriteable();
161 m_objects.put( hint, object );
162 }
163
164
169 protected final Map getObjectMap()
170 {
171 return m_objects;
172 }
173
174
178 public void makeReadOnly()
179 {
180 m_readOnly = true;
181 }
182
183
188 protected final void checkWriteable()
189 throws IllegalStateException
190 {
191 if( m_readOnly )
192 {
193 throw new IllegalStateException
194 ( "ServiceSelector is read only and can not be modified" );
195 }
196 }
197 }
198 |
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