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package com.jme3.network.util;
import com.jme3.network.Message;
import com.jme3.network.MessageConnection;
import com.jme3.network.MessageListener;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* A MessageListener implementation that will forward messages to methods
* of a delegate object. These methods can be automapped or manually
* specified. Subclasses provide specific implementations for how to
* find the actual delegate object.
*
* @author Paul Speed
*/
public abstract class AbstractMessageDelegator
implements MessageListener {
private static final Logger log = Logger.getLogger(AbstractMessageDelegator.class.getName());
private Class delegateType;
private Map methods = new HashMap<>();
private Class[] messageTypes;
/**
* Creates an AbstractMessageDelegator that will forward received
* messages to methods of the specified delegate type. If automap
* is true then reflection is used to lookup probably message handling
* methods.
*/
protected AbstractMessageDelegator( Class delegateType, boolean automap ) {
this.delegateType = delegateType;
if( automap ) {
automap();
}
}
/**
* Returns the array of messages known to be handled by this message
* delegator.
*/
public Class[] getMessageTypes() {
if( messageTypes == null ) {
messageTypes = methods.keySet().toArray(new Class[methods.size()]);
}
return messageTypes;
}
/**
* Returns true if the specified method is valid for the specified
* message type. This is used internally during automapping to
* provide implementation specific filtering of methods.
* This implementation checks for methods that take either the connection and message
* type arguments (in that order) or just the message type.
*/
protected boolean isValidMethod( Method m, Class messageType ) {
if( log.isLoggable(Level.FINEST) ) {
log.log(Level.FINEST, "isValidMethod({0}, {1})", new Object[]{m, messageType});
}
// Parameters must be S and message type or just message type
Class[] parms = m.getParameterTypes();
if( parms.length != 2 && parms.length != 1 ) {
log.finest("Parameter count is not 1 or 2");
return false;
}
int messageIndex = 0;
if( parms.length > 1 ) {
if( MessageConnection.class.isAssignableFrom(parms[0]) ) {
messageIndex++;
} else {
log.finest("First parameter is not a MessageConnection or subclass.");
return false;
}
}
if( messageType == null && !Message.class.isAssignableFrom(parms[messageIndex]) ) {
log.finest("Second parameter is not a Message or subclass.");
return false;
}
if( messageType != null && !parms[messageIndex].isAssignableFrom(messageType) ) {
log.log(Level.FINEST, "Second parameter is not a {0}", messageType);
return false;
}
return true;
}
/**
* Convenience method that returns the message type as
* reflectively determined for a particular method. This
* only works with methods that actually have arguments.
* This implementation returns the last element of the method's
* getParameterTypes() array, thus supporting both
* method(connection, messageType) and method(messageType)
* calling forms.
*/
protected Class getMessageType( Method m ) {
Class[] parms = m.getParameterTypes();
return parms[parms.length-1];
}
/**
* Goes through all of the delegate type's methods to find
* a method of the specified name that may take the specified
* message type.
*/
protected Method findDelegate( String name, Class messageType ) {
// We do an exhaustive search because it's easier to
// check for a variety of parameter types, and it's all
// that Class would be doing in getMethod() anyway.
for( Method m : delegateType.getDeclaredMethods() ) {
if( !m.getName().equals(name) ) {
continue;
}
if( isValidMethod(m, messageType) ) {
return m;
}
}
return null;
}
/**
* Returns true if the specified method name is allowed.
* This is used by automapping to determine if a method
* should be rejected purely on name. Default implementation
* always returns true.
*/
protected boolean allowName( String name ) {
return true;
}
/**
* Calls the map(Set) method with a null argument causing
* all available matching methods to mapped to message types.
*/
protected final void automap() {
map((Set)null);
if( methods.isEmpty() ) {
throw new RuntimeException("No message handling methods found for class:" + delegateType);
}
}
/**
* Specifically maps the specified methods names, autowiring
* the parameters.
*/
public AbstractMessageDelegator map( String... methodNames ) {
Set names = new HashSet<>( Arrays.asList(methodNames) );
map(names);
return this;
}
/**
* Goes through all of the delegate type's declared methods
* mapping methods that match the current constraints.
* If the constraints set is null then allowName() is
* checked for names otherwise only names in the constraints
* set are allowed.
* For each candidate method that passes the above checks,
* isValidMethod() is called with a null message type argument.
* All methods are made accessible thus supporting non-public
* methods as well as public methods.
*/
protected void map( Set constraints ) {
if( log.isLoggable(Level.FINEST) ) {
log.log(Level.FINEST, "map({0})", constraints);
}
for( Method m : delegateType.getDeclaredMethods() ) {
if( log.isLoggable(Level.FINEST) ) {
log.log(Level.FINEST, "Checking method:{0}", m);
}
if( constraints == null && !allowName(m.getName()) ) {
log.finest("Name is not allowed.");
continue;
}
if( constraints != null && !constraints.contains(m.getName()) ) {
log.finest("Name is not in constraints set.");
continue;
}
if( isValidMethod(m, null) ) {
if( log.isLoggable(Level.FINEST) ) {
log.log(Level.FINEST, "Adding method mapping:{0} = {1}", new Object[]{getMessageType(m), m});
}
// Make sure we can access the method even if it's not public or
// is in a non-public inner class.
m.setAccessible(true);
methods.put(getMessageType(m), m);
}
}
messageTypes = null;
}
/**
* Manually maps a specified method to the specified message type.
*/
public AbstractMessageDelegator map( Class messageType, String methodName ) {
// Lookup the method
Method m = findDelegate( methodName, messageType );
if( m == null ) {
throw new RuntimeException( "Method:" + methodName
+ " not found matching signature (MessageConnection, "
+ messageType.getName() + ")" );
}
if( log.isLoggable(Level.FINEST) ) {
log.log(Level.FINEST, "Adding method mapping:{0} = {1}", new Object[]{messageType, m});
}
methods.put( messageType, m );
messageTypes = null;
return this;
}
/**
* Returns the mapped method for the specified message type.
*/
protected Method getMethod( Class c ) {
Method m = methods.get(c);
return m;
}
/**
* Implemented by subclasses to provide the actual delegate object
* against which the mapped message type methods will be called.
*/
protected abstract Object getSourceDelegate( S source );
/**
* Implementation of the MessageListener's messageReceived()
* method that will use the current message type mapping to
* find an appropriate message handling method and call it
* on the delegate returned by getSourceDelegate().
*/
@Override
public void messageReceived( S source, Message msg ) {
if( msg == null ) {
return;
}
Object delegate = getSourceDelegate(source);
if( delegate == null ) {
// Means ignore this message/source
return;
}
Method m = getMethod(msg.getClass());
if( m == null ) {
throw new RuntimeException("Delegate method not found for message class:"
+ msg.getClass());
}
try {
if( m.getParameterTypes().length > 1 ) {
m.invoke( delegate, source, msg );
} else {
m.invoke( delegate, msg );
}
} catch( IllegalAccessException e ) {
throw new RuntimeException("Error executing:" + m, e);
} catch( InvocationTargetException e ) {
throw new RuntimeException("Error executing:" + m, e.getCause());
}
}
}
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