Java example source code file (EventSetDescriptor.java)
The EventSetDescriptor.java Java example source code/*
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*
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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package java.beans;
import java.lang.ref.Reference;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
/**
* An EventSetDescriptor describes a group of events that a given Java
* bean fires.
* <P>
* The given group of events are all delivered as method calls on a single
* event listener interface, and an event listener object can be registered
* via a call on a registration method supplied by the event source.
*/
public class EventSetDescriptor extends FeatureDescriptor {
private MethodDescriptor[] listenerMethodDescriptors;
private MethodDescriptor addMethodDescriptor;
private MethodDescriptor removeMethodDescriptor;
private MethodDescriptor getMethodDescriptor;
private Reference<Method[]> listenerMethodsRef;
private Reference<? extends Class listenerTypeRef;
private boolean unicast;
private boolean inDefaultEventSet = true;
/**
* Creates an <TT>EventSetDescriptor assuming that you are
* following the most simple standard design pattern where a named
* event "fred" is (1) delivered as a call on the single method of
* interface FredListener, (2) has a single argument of type FredEvent,
* and (3) where the FredListener may be registered with a call on an
* addFredListener method of the source component and removed with a
* call on a removeFredListener method.
*
* @param sourceClass The class firing the event.
* @param eventSetName The programmatic name of the event. E.g. "fred".
* Note that this should normally start with a lower-case character.
* @param listenerType The target interface that events
* will get delivered to.
* @param listenerMethodName The method that will get called when the event gets
* delivered to its target listener interface.
* @exception IntrospectionException if an exception occurs during
* introspection.
*/
public EventSetDescriptor(Class<?> sourceClass, String eventSetName,
Class<?> listenerType, String listenerMethodName)
throws IntrospectionException {
this(sourceClass, eventSetName, listenerType,
new String[] { listenerMethodName },
Introspector.ADD_PREFIX + getListenerClassName(listenerType),
Introspector.REMOVE_PREFIX + getListenerClassName(listenerType),
Introspector.GET_PREFIX + getListenerClassName(listenerType) + "s");
String eventName = NameGenerator.capitalize(eventSetName) + "Event";
Method[] listenerMethods = getListenerMethods();
if (listenerMethods.length > 0) {
Class[] args = getParameterTypes(getClass0(), listenerMethods[0]);
// Check for EventSet compliance. Special case for vetoableChange. See 4529996
if (!"vetoableChange".equals(eventSetName) && !args[0].getName().endsWith(eventName)) {
throw new IntrospectionException("Method \"" + listenerMethodName +
"\" should have argument \"" +
eventName + "\"");
}
}
}
private static String getListenerClassName(Class<?> cls) {
String className = cls.getName();
return className.substring(className.lastIndexOf('.') + 1);
}
/**
* Creates an <TT>EventSetDescriptor from scratch using
* string names.
*
* @param sourceClass The class firing the event.
* @param eventSetName The programmatic name of the event set.
* Note that this should normally start with a lower-case character.
* @param listenerType The Class of the target interface that events
* will get delivered to.
* @param listenerMethodNames The names of the methods that will get called
* when the event gets delivered to its target listener interface.
* @param addListenerMethodName The name of the method on the event source
* that can be used to register an event listener object.
* @param removeListenerMethodName The name of the method on the event source
* that can be used to de-register an event listener object.
* @exception IntrospectionException if an exception occurs during
* introspection.
*/
public EventSetDescriptor(Class<?> sourceClass,
String eventSetName,
Class<?> listenerType,
String listenerMethodNames[],
String addListenerMethodName,
String removeListenerMethodName)
throws IntrospectionException {
this(sourceClass, eventSetName, listenerType,
listenerMethodNames, addListenerMethodName,
removeListenerMethodName, null);
}
/**
* This constructor creates an EventSetDescriptor from scratch using
* string names.
*
* @param sourceClass The class firing the event.
* @param eventSetName The programmatic name of the event set.
* Note that this should normally start with a lower-case character.
* @param listenerType The Class of the target interface that events
* will get delivered to.
* @param listenerMethodNames The names of the methods that will get called
* when the event gets delivered to its target listener interface.
* @param addListenerMethodName The name of the method on the event source
* that can be used to register an event listener object.
* @param removeListenerMethodName The name of the method on the event source
* that can be used to de-register an event listener object.
* @param getListenerMethodName The method on the event source that
* can be used to access the array of event listener objects.
* @exception IntrospectionException if an exception occurs during
* introspection.
* @since 1.4
*/
public EventSetDescriptor(Class<?> sourceClass,
String eventSetName,
Class<?> listenerType,
String listenerMethodNames[],
String addListenerMethodName,
String removeListenerMethodName,
String getListenerMethodName)
throws IntrospectionException {
if (sourceClass == null || eventSetName == null || listenerType == null) {
throw new NullPointerException();
}
setName(eventSetName);
setClass0(sourceClass);
setListenerType(listenerType);
Method[] listenerMethods = new Method[listenerMethodNames.length];
for (int i = 0; i < listenerMethodNames.length; i++) {
// Check for null names
if (listenerMethodNames[i] == null) {
throw new NullPointerException();
}
listenerMethods[i] = getMethod(listenerType, listenerMethodNames[i], 1);
}
setListenerMethods(listenerMethods);
setAddListenerMethod(getMethod(sourceClass, addListenerMethodName, 1));
setRemoveListenerMethod(getMethod(sourceClass, removeListenerMethodName, 1));
// Be more forgiving of not finding the getListener method.
Method method = Introspector.findMethod(sourceClass, getListenerMethodName, 0);
if (method != null) {
setGetListenerMethod(method);
}
}
private static Method getMethod(Class<?> cls, String name, int args)
throws IntrospectionException {
if (name == null) {
return null;
}
Method method = Introspector.findMethod(cls, name, args);
if ((method == null) || Modifier.isStatic(method.getModifiers())) {
throw new IntrospectionException("Method not found: " + name +
" on class " + cls.getName());
}
return method;
}
/**
* Creates an <TT>EventSetDescriptor from scratch using
* <TT>java.lang.reflect.Method and java.lang.Class objects.
*
* @param eventSetName The programmatic name of the event set.
* @param listenerType The Class for the listener interface.
* @param listenerMethods An array of Method objects describing each
* of the event handling methods in the target listener.
* @param addListenerMethod The method on the event source
* that can be used to register an event listener object.
* @param removeListenerMethod The method on the event source
* that can be used to de-register an event listener object.
* @exception IntrospectionException if an exception occurs during
* introspection.
*/
public EventSetDescriptor(String eventSetName,
Class<?> listenerType,
Method listenerMethods[],
Method addListenerMethod,
Method removeListenerMethod)
throws IntrospectionException {
this(eventSetName, listenerType, listenerMethods,
addListenerMethod, removeListenerMethod, null);
}
/**
* This constructor creates an EventSetDescriptor from scratch using
* java.lang.reflect.Method and java.lang.Class objects.
*
* @param eventSetName The programmatic name of the event set.
* @param listenerType The Class for the listener interface.
* @param listenerMethods An array of Method objects describing each
* of the event handling methods in the target listener.
* @param addListenerMethod The method on the event source
* that can be used to register an event listener object.
* @param removeListenerMethod The method on the event source
* that can be used to de-register an event listener object.
* @param getListenerMethod The method on the event source
* that can be used to access the array of event listener objects.
* @exception IntrospectionException if an exception occurs during
* introspection.
* @since 1.4
*/
public EventSetDescriptor(String eventSetName,
Class<?> listenerType,
Method listenerMethods[],
Method addListenerMethod,
Method removeListenerMethod,
Method getListenerMethod)
throws IntrospectionException {
setName(eventSetName);
setListenerMethods(listenerMethods);
setAddListenerMethod(addListenerMethod);
setRemoveListenerMethod( removeListenerMethod);
setGetListenerMethod(getListenerMethod);
setListenerType(listenerType);
}
/**
* Creates an <TT>EventSetDescriptor from scratch using
* <TT>java.lang.reflect.MethodDescriptor and java.lang.Class
* objects.
*
* @param eventSetName The programmatic name of the event set.
* @param listenerType The Class for the listener interface.
* @param listenerMethodDescriptors An array of MethodDescriptor objects
* describing each of the event handling methods in the
* target listener.
* @param addListenerMethod The method on the event source
* that can be used to register an event listener object.
* @param removeListenerMethod The method on the event source
* that can be used to de-register an event listener object.
* @exception IntrospectionException if an exception occurs during
* introspection.
*/
public EventSetDescriptor(String eventSetName,
Class<?> listenerType,
MethodDescriptor listenerMethodDescriptors[],
Method addListenerMethod,
Method removeListenerMethod)
throws IntrospectionException {
setName(eventSetName);
this.listenerMethodDescriptors = (listenerMethodDescriptors != null)
? listenerMethodDescriptors.clone()
: null;
setAddListenerMethod(addListenerMethod);
setRemoveListenerMethod(removeListenerMethod);
setListenerType(listenerType);
}
/**
* Gets the <TT>Class object for the target interface.
*
* @return The Class object for the target interface that will
* get invoked when the event is fired.
*/
public Class<?> getListenerType() {
return (this.listenerTypeRef != null)
? this.listenerTypeRef.get()
: null;
}
private void setListenerType(Class<?> cls) {
this.listenerTypeRef = getWeakReference(cls);
}
/**
* Gets the methods of the target listener interface.
*
* @return An array of <TT>Method objects for the target methods
* within the target listener interface that will get called when
* events are fired.
*/
public synchronized Method[] getListenerMethods() {
Method[] methods = getListenerMethods0();
if (methods == null) {
if (listenerMethodDescriptors != null) {
methods = new Method[listenerMethodDescriptors.length];
for (int i = 0; i < methods.length; i++) {
methods[i] = listenerMethodDescriptors[i].getMethod();
}
}
setListenerMethods(methods);
}
return methods;
}
private void setListenerMethods(Method[] methods) {
if (methods == null) {
return;
}
if (listenerMethodDescriptors == null) {
listenerMethodDescriptors = new MethodDescriptor[methods.length];
for (int i = 0; i < methods.length; i++) {
listenerMethodDescriptors[i] = new MethodDescriptor(methods[i]);
}
}
this.listenerMethodsRef = getSoftReference(methods);
}
private Method[] getListenerMethods0() {
return (this.listenerMethodsRef != null)
? this.listenerMethodsRef.get()
: null;
}
/**
* Gets the <code>MethodDescriptors of the target listener interface.
*
* @return An array of <code>MethodDescriptor objects for the target methods
* within the target listener interface that will get called when
* events are fired.
*/
public synchronized MethodDescriptor[] getListenerMethodDescriptors() {
return (this.listenerMethodDescriptors != null)
? this.listenerMethodDescriptors.clone()
: null;
}
/**
* Gets the method used to add event listeners.
*
* @return The method used to register a listener at the event source.
*/
public synchronized Method getAddListenerMethod() {
return getMethod(this.addMethodDescriptor);
}
private synchronized void setAddListenerMethod(Method method) {
if (method == null) {
return;
}
if (getClass0() == null) {
setClass0(method.getDeclaringClass());
}
addMethodDescriptor = new MethodDescriptor(method);
setTransient(method.getAnnotation(Transient.class));
}
/**
* Gets the method used to remove event listeners.
*
* @return The method used to remove a listener at the event source.
*/
public synchronized Method getRemoveListenerMethod() {
return getMethod(this.removeMethodDescriptor);
}
private synchronized void setRemoveListenerMethod(Method method) {
if (method == null) {
return;
}
if (getClass0() == null) {
setClass0(method.getDeclaringClass());
}
removeMethodDescriptor = new MethodDescriptor(method);
setTransient(method.getAnnotation(Transient.class));
}
/**
* Gets the method used to access the registered event listeners.
*
* @return The method used to access the array of listeners at the event
* source or null if it doesn't exist.
* @since 1.4
*/
public synchronized Method getGetListenerMethod() {
return getMethod(this.getMethodDescriptor);
}
private synchronized void setGetListenerMethod(Method method) {
if (method == null) {
return;
}
if (getClass0() == null) {
setClass0(method.getDeclaringClass());
}
getMethodDescriptor = new MethodDescriptor(method);
setTransient(method.getAnnotation(Transient.class));
}
/**
* Mark an event set as unicast (or not).
*
* @param unicast True if the event set is unicast.
*/
public void setUnicast(boolean unicast) {
this.unicast = unicast;
}
/**
* Normally event sources are multicast. However there are some
* exceptions that are strictly unicast.
*
* @return <TT>true if the event set is unicast.
* Defaults to <TT>false.
*/
public boolean isUnicast() {
return unicast;
}
/**
* Marks an event set as being in the "default" set (or not).
* By default this is <TT>true.
*
* @param inDefaultEventSet <code>true if the event set is in
* the "default" set,
* <code>false if not
*/
public void setInDefaultEventSet(boolean inDefaultEventSet) {
this.inDefaultEventSet = inDefaultEventSet;
}
/**
* Reports if an event set is in the "default" set.
*
* @return <TT>true if the event set is in
* the "default" set. Defaults to <TT>true.
*/
public boolean isInDefaultEventSet() {
return inDefaultEventSet;
}
/*
* Package-private constructor
* Merge two event set descriptors. Where they conflict, give the
* second argument (y) priority over the first argument (x).
*
* @param x The first (lower priority) EventSetDescriptor
* @param y The second (higher priority) EventSetDescriptor
*/
EventSetDescriptor(EventSetDescriptor x, EventSetDescriptor y) {
super(x,y);
listenerMethodDescriptors = x.listenerMethodDescriptors;
if (y.listenerMethodDescriptors != null) {
listenerMethodDescriptors = y.listenerMethodDescriptors;
}
listenerTypeRef = x.listenerTypeRef;
if (y.listenerTypeRef != null) {
listenerTypeRef = y.listenerTypeRef;
}
addMethodDescriptor = x.addMethodDescriptor;
if (y.addMethodDescriptor != null) {
addMethodDescriptor = y.addMethodDescriptor;
}
removeMethodDescriptor = x.removeMethodDescriptor;
if (y.removeMethodDescriptor != null) {
removeMethodDescriptor = y.removeMethodDescriptor;
}
getMethodDescriptor = x.getMethodDescriptor;
if (y.getMethodDescriptor != null) {
getMethodDescriptor = y.getMethodDescriptor;
}
unicast = y.unicast;
if (!x.inDefaultEventSet || !y.inDefaultEventSet) {
inDefaultEventSet = false;
}
}
/*
* Package-private dup constructor
* This must isolate the new object from any changes to the old object.
*/
EventSetDescriptor(EventSetDescriptor old) {
super(old);
if (old.listenerMethodDescriptors != null) {
int len = old.listenerMethodDescriptors.length;
listenerMethodDescriptors = new MethodDescriptor[len];
for (int i = 0; i < len; i++) {
listenerMethodDescriptors[i] = new MethodDescriptor(
old.listenerMethodDescriptors[i]);
}
}
listenerTypeRef = old.listenerTypeRef;
addMethodDescriptor = old.addMethodDescriptor;
removeMethodDescriptor = old.removeMethodDescriptor;
getMethodDescriptor = old.getMethodDescriptor;
unicast = old.unicast;
inDefaultEventSet = old.inDefaultEventSet;
}
void appendTo(StringBuilder sb) {
appendTo(sb, "unicast", this.unicast);
appendTo(sb, "inDefaultEventSet", this.inDefaultEventSet);
appendTo(sb, "listenerType", this.listenerTypeRef);
appendTo(sb, "getListenerMethod", getMethod(this.getMethodDescriptor));
appendTo(sb, "addListenerMethod", getMethod(this.addMethodDescriptor));
appendTo(sb, "removeListenerMethod", getMethod(this.removeMethodDescriptor));
}
private static Method getMethod(MethodDescriptor descriptor) {
return (descriptor != null)
? descriptor.getMethod()
: null;
}
}
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