org.simpleframework.xml.core.Builder Maven / Gradle / Ivy
/*
* Builder.java April 2009
*
* Copyright (C) 2009, Niall Gallagher
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
* Public License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307 USA
*/
package org.simpleframework.xml.core;
import java.lang.reflect.Constructor;
import java.util.List;
/**
* The Builder object is used to represent an single
* constructor within an object. It contains the actual constructor
* as well as the list of parameters. Each builder will score its
* weight when given a Criteria object. This allows
* the deserialization process to find the most suitable one to
* use when instantiating an object.
*
* @author Niall Gallagher
*/
class Builder {
/**
* This is the list of parameters in the order of declaration.
*/
private final List list;
/**
* This is the factory that is used to instantiate the object.
*/
private final Constructor factory;
/**
* This is the map that contains the parameters to be used.
*/
private final Index index;
/**
* Constructor for the Builder object. This is used
* to create a factory like object used for instantiating objects.
* Each builder will score its suitability using the parameters
* it is provided.
*
* @param factory this is the factory used for instantiation
* @param index this is the map of parameters that are declared
*/
public Builder(Constructor factory, Index index) {
this.list = index.getParameters();
this.factory = factory;
this.index = index;
}
/**
* This is used to determine if this Builder is a
* default constructor. If the class does contain a no argument
* constructor then this will return true.
*
* @return true if the class has a default constructor
*/
public boolean isDefault() {
return index.size() == 0;
}
/**
* This is used to acquire the named Parameter from
* the builder. A parameter is taken from the constructor which
* contains annotations for each object that is required. These
* parameters must have a matching field or method.
*
* @param name this is the name of the parameter to be acquired
*
* @return this returns the named parameter for the builder
*/
public Parameter getParameter(String name) {
return index.get(name);
}
/**
* This is used to instantiate the object using the default no
* argument constructor. If for some reason the object can not be
* instantiated then this will throw an exception with the reason.
*
* @return this returns the object that has been instantiated
*/
public Object getInstance() throws Exception {
if(!factory.isAccessible()) {
factory.setAccessible(true);
}
return factory.newInstance();
}
/**
* This is used to instantiate the object using a constructor that
* takes deserialized objects as arguments. The object that have
* been deserialized can be taken from the Criteria
* object which contains the deserialized values.
*
* @param criteria this contains the criteria to be used
*
* @return this returns the object that has been instantiated
*/
public Object getInstance(Criteria criteria) throws Exception {
Object[] values = list.toArray();
for(int i = 0; i < list.size(); i++) {
String name = list.get(i).getName();
Variable variable = criteria.remove(name);
Object value = variable.getValue();
values[i] = value;
}
return factory.newInstance(values);
}
/**
* This is used to score this Builder object so that
* it can be weighed amongst other constructors. The builder that
* scores the highest is the one that is used for instantiation.
*
* @param criteria this contains the criteria to be used
*
* @return this returns the score based on the criteria provided
*/
public int score(Criteria criteria) throws Exception {
int score = 0;
for(int i = 0; i < list.size(); i++) {
String name = list.get(i).getName();
Label label = criteria.get(name);
if(label == null) {
return -1;
}
score++;
}
return score;
}
/**
* This is used to acquire a descriptive name for the builder.
* Providing a name is useful in debugging and when exceptions are
* thrown as it describes the constructor the builder represents.
*
* @return this returns the name of the constructor to be used
*/
public String toString() {
return factory.toString();
}
}