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/*
* FieldContact.java April 2007
*
* Copyright (C) 2007, Niall Gallagher
*
* 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.simpleframework.xml.core;
import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import org.simpleframework.xml.util.Cache;
import org.simpleframework.xml.util.ConcurrentCache;
/**
* The FieldContact object is used to act as a contact
* for a field within an object. This allows a value to be set on an
* object field during deserialization and acquired from the same
* field during serialization.
*
* @author Niall Gallagher
*
* @see org.simpleframework.xml.core.FieldScanner
*/
class FieldContact implements Contact {
/**
* This cache contains the annotations present on the field.
*/
private final Cache cache;
/**
* This is the list of annotations associated with the field.
*/
private final Annotation[] list;
/**
* This is the label that marks the field within the object.
*/
private final Annotation label;
/**
* This represents the field within the schema class object.
*/
private final Field field;
/**
* This is the name for this contact as taken from the field.
*/
private final String name;
/**
* This is the modifiers for the field that this represents.
*/
private final int modifier;
/**
* Constructor for the FieldContact object. This is
* used as a point of contact for a field within a schema class.
* Values can be read and written directly to the field with this.
*
* @param field this is the field that is the point of contact
* @param label this is the annotation that is used by the field
* @param list this is the list of annotations on the field
*/
public FieldContact(Field field, Annotation label, Annotation[] list) {
this.cache = new ConcurrentCache();
this.modifier = field.getModifiers();
this.name = field.getName();
this.label = label;
this.field = field;
this.list = list;
}
/**
* This is used to determine if the annotated contact is for a
* read only variable. A read only variable is a field that
* can be set from within the constructor such as a blank final
* variable. It can also be a method with no set counterpart.
*
* @return this returns true if the contact is a constant one
*/
public boolean isReadOnly() {
return !isStatic() && isFinal();
}
/**
* This is used to determine if the annotated contact is for a
* static field or method. A static field or method is one that
* contains the "static" keyword. Any static final fields will
* be read only and does not require any matching annotation.
*
* @return this returns true if the contact is a static one
*/
public boolean isStatic() {
return Modifier.isStatic(modifier);
}
/**
* This is used to identify annotated methods are fields that
* can not be modified. Such field will require that there is
* a constructor that can have the value injected in to it.
*
* @return this returns true if the field or method is final
*/
public boolean isFinal() {
return Modifier.isFinal(modifier);
}
/**
* This will provide the contact type. The contact type is the
* class that is to be set and get on the object. This represents
* the return type for the get and the parameter for the set.
*
* @return this returns the type that this contact represents
*/
public Class getType() {
return field.getType();
}
/**
* This provides the dependent class for the contact. This will
* actually represent a generic type for the actual type. For
* contacts that use a Collection type this will
* be the generic type parameter for that collection.
*
* @return this returns the dependent type for the contact
*/
public Class getDependent() {
return Reflector.getDependent(field);
}
/**
* This provides the dependent classes for the contact. This will
* typically represent a generic types for the actual type. For
* contacts that use a Map type this will be the
* generic type parameter for that map type declaration.
*
* @return this returns the dependent type for the contact
*/
public Class[] getDependents() {
return Reflector.getDependents(field);
}
/**
* This is the class that declares the contact. The declaring
* class is where the field represented been defined. This will
* typically be a class rather than an interface.
*
* @return this returns the class the contact is declared within
*/
public Class getDeclaringClass() {
return field.getDeclaringClass();
}
/**
* This is used to acquire the name of the field. This will return
* the name of the field which can then be used to determine the
* XML attribute or element the contact represents. This ensures
* that the name provided string is internalized for performance.
*
* @return this returns the name of the field represented
*/
public String getName() {
return name;
}
/**
* This is the annotation associated with the point of contact.
* This will be an XML annotation that describes how the contact
* should be serialized and deserialized from the object.
*
* @return this provides the annotation associated with this
*/
public Annotation getAnnotation() {
return label;
}
/**
* This is the annotation associated with the point of contact.
* This will be an XML annotation that describes how the contact
* should be serialized and deserialized from the object.
*
* @param type this is the type of the annotation to acquire
*
* @return this provides the annotation associated with this
*/
public T getAnnotation(Class type) {
if(type == label.annotationType()) {
return (T) label;
}
return getCache(type);
}
/**
* This is the annotation associated with the point of contact.
* This will be an XML annotation that describes how the contact
* should be serialized and deserialized from the object.
*
* @param type this is the type of the annotation to acquire
*
* @return this provides the annotation associated with this
*/
private T getCache(Class type) {
if(cache.isEmpty()) {
for(Annotation entry : list) {
Class key = entry.annotationType();
cache.cache(key, entry);
}
}
return (T)cache.fetch(type);
}
/**
* This is used to set the specified value on the provided object.
* The value provided must be an instance of the contact class so
* that it can be set without a runtime class compatibility error.
*
* @param source this is the object to set the value on
* @param value this is the value that is to be set on the object
*/
public void set(Object source, Object value) throws Exception {
if(!isFinal()) {
field.set(source, value);
}
}
/**
* This is used to get the specified value on the provided object.
* The value returned from this method will be an instance of the
* contact class type. If the returned object is of a different
* type then the serialization process will fail.
*
* @param source this is the object to acquire the value from
*
* @return this is the value that is acquired from the object
*/
public Object get(Object source) throws Exception {
return field.get(source);
}
/**
* This is used to describe the contact as it exists within the
* owning class. It is used to provide error messages that can
* be used to debug issues that occur when processing a contact.
* The string provided is the generic field string.
*
* @return this returns a string representation of the contact
*/
public String toString() {
return String.format("field '%s' %s", getName(), field.toString());
}
}