/*
* Copyright 2008 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.wamblee.system.adapters;
import java.lang.reflect.Constructor;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import org.wamblee.collections.CollectionFilter;
import org.wamblee.conditions.Condition;
import org.wamblee.system.core.RequiredInterface;
import org.wamblee.system.core.Scope;
import org.wamblee.system.core.SystemAssemblyException;
/**
* Class that allows configuration of the constructor to use.
*
* In particular, it provides:
*
* - Selection of a constructor using explicit selection
* {@link #select(Class...)} or using the most greedy constructor
* {@link #greedy()}.
*
* -
* Selection of methods to invoke to inject other objects into the object.
*
* - Selection of fields to set.
*
*
*/
public class ConstructorConfiguration {
private Class _class;
private Constructor> _constructor;
private ParameterValues _values;
private boolean _publicOnly;
/**
* Constructs the configuration. By default the public constructor with the
* most arguments will be used.
* @param aClass Class to construct.
*/
public ConstructorConfiguration(Class aClass) {
_class = aClass;
_constructor = null;
_publicOnly = true;
}
/**
* Sets whether or no non public constructors are also considered.
* Reset the choice of a constructor to its default.
* @param aNonPublic
* @return
*/
public ConstructorConfiguration setNonPublic(boolean aNonPublic) {
_publicOnly = !aNonPublic;
_constructor = null;
_values = null;
return this;
}
/**
* Selects an explicit constructor.
* @param aTypes Arguments of the constructor.
* @return Return the injector to allow call chaining.
*/
public ConstructorConfiguration select(Class... aTypes) {
try {
_constructor = _class.getDeclaredConstructor(aTypes);
} catch (Exception e) {
throw new SystemAssemblyException(e.getMessage(), e);
}
resetValues();
return this;
}
/**
* Selects the greediest constructor.
* @return The injector to allow call chaining.
* @throws SystemAssemblyException if the greediest constructor cannot be uniquely
* identified.
*/
public ConstructorConfiguration greedy() {
Constructor>[] declared = _class.getDeclaredConstructors();
if (declared.length == 0) {
throw new SystemAssemblyException("Class '" + _class
+ " is an interface, primitive type, or array");
}
int max = -1;
List> checked = new ArrayList>();
CollectionFilter.filter(Arrays.asList(declared), checked,
new Condition>() {
@Override
public boolean matches(Constructor> aObject) {
if ( !_publicOnly ) {
return true;
} else {
return Modifier.isPublic(aObject.getModifiers());
}
}
});
for (Constructor ctor : checked) {
if (ctor.getParameterTypes().length > max) {
max = ctor.getParameterTypes().length;
}
}
final int max2 = max;
List> ctors = checked;
List> longest = new ArrayList>();
CollectionFilter.filter(ctors, longest,
new Condition>() {
@Override
public boolean matches(Constructor> aObject) {
return aObject.getParameterTypes().length == max2;
}
});
if (longest.size() > 1) {
throw new SystemAssemblyException(
"Greediest constructor cannot be uniquely determined");
}
_constructor = longest.get(0);
resetValues();
return this;
}
public ParameterValues getParameters() {
getConstructor(); // initialize constructor if needed.
return _values;
}
/**
* Resets the values.
*/
private void resetValues() {
_constructor.setAccessible(true);
_values = new ParameterValues(_constructor.getParameterTypes());
}
/**
* Creates the object in the given scope.
* @param aScope Scope containing required interfaces for this object.
* @return object.
*/
public Object create(Scope aScope) {
Object[] values = _values.values(aScope);
try {
return getConstructor().newInstance(values);
} catch (Exception e) {
throw new SystemAssemblyException("Could not construct object "
+ getConstructor() + " " + Arrays.asList(values), e);
}
}
public List getRequiredInterfaces() {
getConstructor(); // initialize constructor if needed.
return _values.getRequiredInterfaces();
}
private Constructor getConstructor() {
if (_constructor == null ) {
greedy();
}
return _constructor;
}
}