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Spring Framework example source code file (FieldRetrievingFactoryBean.java)

This example Spring Framework source code file (FieldRetrievingFactoryBean.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Spring Framework tags/keywords

class, class, classloader, factorybean, illegalaccessexception, illegalargumentexception, illegalargumentexception, initializingbean, nosuchfieldexception, object, object, reflection, specify, string, string

The Spring Framework FieldRetrievingFactoryBean.java source code

/*
 * Copyright 2002-2007 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.springframework.beans.factory.config;

import java.lang.reflect.Field;

import org.springframework.beans.factory.BeanClassLoaderAware;
import org.springframework.beans.factory.BeanFactoryUtils;
import org.springframework.beans.factory.BeanNameAware;
import org.springframework.beans.factory.FactoryBean;
import org.springframework.beans.factory.FactoryBeanNotInitializedException;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.util.ClassUtils;
import org.springframework.util.ReflectionUtils;
import org.springframework.util.StringUtils;

/**
 * FactoryBean which retrieves a static or non-static field value.
 * 
 * <p>Typically used for retrieving public static final constants. Usage example:
 *
 * <pre class="code">// standard definition for exposing a static field, specifying the "staticField" property
 * <bean id="myField" class="org.springframework.beans.factory.config.FieldRetrievingFactoryBean">
 *   <property name="staticField" value="java.sql.Connection.TRANSACTION_SERIALIZABLE"/>
 * </bean>
 *
 * // convenience version that specifies a static field pattern as bean name
 * <bean id="java.sql.Connection.TRANSACTION_SERIALIZABLE"
 *       class="org.springframework.beans.factory.config.FieldRetrievingFactoryBean"/></pre>
 * </pre>
 * 
 * <p>If you are using Spring 2.0, you can also use the following style of configuration for
 * public static fields.
 * 
 * <pre class="code"><util:constant static-field="java.sql.Connection.TRANSACTION_SERIALIZABLE"/>
* * @author Juergen Hoeller * @since 1.1 * @see #setStaticField */ public class FieldRetrievingFactoryBean implements FactoryBean, BeanNameAware, BeanClassLoaderAware, InitializingBean { private Class targetClass; private Object targetObject; private String targetField; private String staticField; private String beanName; private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader(); // the field we will retrieve private Field fieldObject; /** * Set the target class on which the field is defined. * Only necessary when the target field is static; else, * a target object needs to be specified anyway. * @see #setTargetObject * @see #setTargetField */ public void setTargetClass(Class targetClass) { this.targetClass = targetClass; } /** * Return the target class on which the field is defined. */ public Class getTargetClass() { return targetClass; } /** * Set the target object on which the field is defined. * Only necessary when the target field is not static; * else, a target class is sufficient. * @see #setTargetClass * @see #setTargetField */ public void setTargetObject(Object targetObject) { this.targetObject = targetObject; } /** * Return the target object on which the field is defined. */ public Object getTargetObject() { return this.targetObject; } /** * Set the name of the field to be retrieved. * Refers to either a static field or a non-static field, * depending on a target object being set. * @see #setTargetClass * @see #setTargetObject */ public void setTargetField(String targetField) { this.targetField = StringUtils.trimAllWhitespace(targetField); } /** * Return the name of the field to be retrieved. */ public String getTargetField() { return this.targetField; } /** * Set a fully qualified static field name to retrieve, * e.g. "example.MyExampleClass.MY_EXAMPLE_FIELD". * Convenient alternative to specifying targetClass and targetField. * @see #setTargetClass * @see #setTargetField */ public void setStaticField(String staticField) { this.staticField = StringUtils.trimAllWhitespace(staticField); } /** * The bean name of this FieldRetrievingFactoryBean will be interpreted * as "staticField" pattern, if neither "targetClass" nor "targetObject" * nor "targetField" have been specified. * This allows for concise bean definitions with just an id/name. */ public void setBeanName(String beanName) { this.beanName = StringUtils.trimAllWhitespace(BeanFactoryUtils.originalBeanName(beanName)); } public void setBeanClassLoader(ClassLoader classLoader) { this.beanClassLoader = classLoader; } public void afterPropertiesSet() throws ClassNotFoundException, NoSuchFieldException { if (this.targetClass != null && this.targetObject != null) { throw new IllegalArgumentException("Specify either targetClass or targetObject, not both"); } if (this.targetClass == null && this.targetObject == null) { if (this.targetField != null) { throw new IllegalArgumentException( "Specify targetClass or targetObject in combination with targetField"); } // If no other property specified, consider bean name as static field expression. if (this.staticField == null) { this.staticField = this.beanName; } // Try to parse static field into class and field. int lastDotIndex = this.staticField.lastIndexOf('.'); if (lastDotIndex == -1 || lastDotIndex == this.staticField.length()) { throw new IllegalArgumentException( "staticField must be a fully qualified class plus method name: " + "e.g. 'example.MyExampleClass.MY_EXAMPLE_FIELD'"); } String className = this.staticField.substring(0, lastDotIndex); String fieldName = this.staticField.substring(lastDotIndex + 1); this.targetClass = ClassUtils.forName(className, this.beanClassLoader); this.targetField = fieldName; } else if (this.targetField == null) { // Either targetClass or targetObject specified. throw new IllegalArgumentException("targetField is required"); } // Try to get the exact method first. Class targetClass = (this.targetObject != null) ? this.targetObject.getClass() : this.targetClass; this.fieldObject = targetClass.getField(this.targetField); } public Object getObject() throws IllegalAccessException { if (this.fieldObject == null) { throw new FactoryBeanNotInitializedException(); } ReflectionUtils.makeAccessible(this.fieldObject); if (this.targetObject != null) { // instance field return this.fieldObject.get(this.targetObject); } else{ // class field return this.fieldObject.get(null); } } public Class getObjectType() { return (this.fieldObject != null ? this.fieldObject.getType() : null); } public boolean isSingleton() { return false; } }

Other Spring Framework examples (source code examples)

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