/*
* Copyright 2005-2010 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 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;
import java.lang.reflect.Constructor;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
/**
* 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 clazz;
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) {
clazz = 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.
*
* @return Return the injector to allow call chaining.
*
*/
public ConstructorConfiguration select(Class... aTypes) {
try {
constructor = clazz.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 = clazz.getDeclaredConstructors();
if (declared.length == 0) {
throw new SystemAssemblyException("Class '" + clazz +
" 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;
}
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[] valueArray = values.values(aScope);
try {
return getConstructor().newInstance(valueArray);
} catch (Exception e) {
throw new SystemAssemblyException("Could not construct object " +
getConstructor() + " " + Arrays.asList(valueArray), e);
}
}
public List getRequiredInterfaces() {
getConstructor(); // initialize constructor if needed.
return values.getRequiredInterfaces();
}
private Constructor getConstructor() {
if (constructor == null) {
greedy();
}
return constructor;
}
}