001 /*****************************************************************************
002 * Copyright (C) PicoContainer Organization. All rights reserved. *
003 * ------------------------------------------------------------------------- *
004 * The software in this package is published under the terms of the BSD *
005 * style license a copy of which has been included with this distribution in *
006 * the LICENSE.txt file. *
007 * *
008 * Original code by *
009 *****************************************************************************/
010 package org.picocontainer.adapters;
011
012 import org.picocontainer.ComponentMonitor;
013 import org.picocontainer.PicoVisitor;
014 import org.picocontainer.ComponentAdapter;
015 import org.picocontainer.ComponentMonitorStrategy;
016 import org.picocontainer.PicoContainer;
017 import org.picocontainer.PicoCompositionException;
018 import org.picocontainer.injectors.ProviderAdapter;
019 import org.picocontainer.injectors.Provider;
020 import org.picocontainer.monitors.AbstractComponentMonitor;
021 import org.picocontainer.monitors.NullComponentMonitor;
022
023 import java.io.Serializable;
024
025 /**
026 * Base class for a ComponentAdapter with general functionality.
027 * This implementation provides basic checks for a healthy implementation of a ComponentAdapter.
028 * It does not allow to use <code>null</code> for the component key or the implementation,
029 * ensures that the implementation is a concrete class and that the key is assignable from the
030 * implementation if the key represents a type.
031 *
032 * @author Paul Hammant
033 * @author Aslak Hellesøy
034 * @author Jon Tirsén
035 */
036 public abstract class AbstractAdapter<T> implements ComponentAdapter<T>, ComponentMonitorStrategy, Serializable {
037 private Object componentKey;
038 private Class<T> componentImplementation;
039 private ComponentMonitor componentMonitor;
040
041 /**
042 * Constructs a new ComponentAdapter for the given key and implementation.
043 * @param componentKey the search key for this implementation
044 * @param componentImplementation the concrete implementation
045 */
046 public AbstractAdapter(Object componentKey, Class componentImplementation) {
047 this(componentKey, componentImplementation, new AbstractComponentMonitor());
048 this.componentMonitor = new NullComponentMonitor();
049 }
050
051 /**
052 * Constructs a new ComponentAdapter for the given key and implementation.
053 * @param componentKey the search key for this implementation
054 * @param componentImplementation the concrete implementation
055 * @param monitor the component monitor used by this ComponentAdapter
056 */
057 public AbstractAdapter(Object componentKey, Class componentImplementation, ComponentMonitor monitor) {
058 if (monitor == null) {
059 throw new NullPointerException("ComponentMonitor==null");
060 }
061 this.componentMonitor = monitor;
062 if (componentImplementation == null) {
063 throw new NullPointerException("componentImplementation");
064 }
065 this.componentKey = componentKey;
066 this.componentImplementation = componentImplementation;
067 checkTypeCompatibility();
068 }
069
070 /**
071 * {@inheritDoc}
072 * @see org.picocontainer.ComponentAdapter#getComponentKey()
073 */
074 public Object getComponentKey() {
075 if (componentKey == null) {
076 throw new NullPointerException("componentKey");
077 }
078 return componentKey;
079 }
080
081 /**
082 * {@inheritDoc}
083 * @see org.picocontainer.ComponentAdapter#getComponentImplementation()
084 */
085 public Class<T> getComponentImplementation() {
086 return componentImplementation;
087 }
088
089 protected void checkTypeCompatibility() {
090 if (componentKey instanceof Class) {
091 Class<?> componentType = (Class) componentKey;
092 if (Provider.class.isAssignableFrom(componentImplementation)) {
093 if (!componentType.isAssignableFrom(ProviderAdapter.getProvideMethod(componentImplementation).getReturnType())) {
094 throw newCCE(componentType);
095 }
096 } else {
097 if (!componentType.isAssignableFrom(componentImplementation)) {
098 throw newCCE(componentType);
099 }
100 }
101 }
102 }
103
104 private ClassCastException newCCE(Class<?> componentType) {
105 return new ClassCastException(componentImplementation.getName() + " is not a " + componentType.getName());
106 }
107
108 public T getComponentInstance(PicoContainer container) throws PicoCompositionException {
109 return getComponentInstance(container, null);
110 }
111
112 /**
113 * @return Returns the ComponentAdapter's class name and the component's key.
114 * @see java.lang.Object#toString()
115 */
116 public String toString() {
117 return getDescriptor() + getComponentKey();
118 }
119
120 public void accept(PicoVisitor visitor) {
121 visitor.visitComponentAdapter(this);
122 }
123
124 public void changeMonitor(ComponentMonitor monitor) {
125 this.componentMonitor = monitor;
126 }
127
128 /**
129 * Returns the monitor currently used
130 * @return The ComponentMonitor currently used
131 */
132 public ComponentMonitor currentMonitor(){
133 return componentMonitor;
134 }
135
136 public final ComponentAdapter<T> getDelegate() {
137 return null;
138 }
139
140 public final <U extends ComponentAdapter> U findAdapterOfType(Class<U> adapterType) {
141 if (adapterType.isAssignableFrom(this.getClass())) {
142 return (U) this;
143 } else if (getDelegate() != null) {
144 return getDelegate().findAdapterOfType(adapterType);
145 }
146 return null;
147 }
148
149
150 }