org.springframework.beans.factory.config.PropertyResourceConfigurer.java Source code

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Here is the source code for org.springframework.beans.factory.config.PropertyResourceConfigurer.java

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/*
 * Copyright 2002-2012 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
 *
 *      https://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.io.IOException;
import java.util.Enumeration;
import java.util.Properties;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanInitializationException;
import org.springframework.core.Ordered;
import org.springframework.core.PriorityOrdered;
import org.springframework.core.io.support.PropertiesLoaderSupport;
import org.springframework.util.ObjectUtils;

/**
 * Allows for configuration of individual bean property values from a property resource,
 * i.e. a properties file. Useful for custom config files targeted at system
 * administrators that override bean properties configured in the application context.
 *
 * <p>Two concrete implementations are provided in the distribution:
 * <ul>
 * <li>{@link PropertyOverrideConfigurer} for "beanName.property=value" style overriding
 * (<i>pushing</i> values from a properties file into bean definitions)
 * <li>{@link PropertyPlaceholderConfigurer} for replacing "${...}" placeholders
 * (<i>pulling</i> values from a properties file into bean definitions)
 * </ul>
 *
 * <p>Property values can be converted after reading them in, through overriding
 * the {@link #convertPropertyValue} method. For example, encrypted values
 * can be detected and decrypted accordingly before processing them.
 *
 * @author Juergen Hoeller
 * @since 02.10.2003
 * @see PropertyOverrideConfigurer
 * @see PropertyPlaceholderConfigurer
 */
public abstract class PropertyResourceConfigurer extends PropertiesLoaderSupport
        implements BeanFactoryPostProcessor, PriorityOrdered {

    private int order = Ordered.LOWEST_PRECEDENCE; // default: same as non-Ordered

    /**
     * Set the order value of this object for sorting purposes.
     * @see PriorityOrdered
     */
    public void setOrder(int order) {
        this.order = order;
    }

    @Override
    public int getOrder() {
        return this.order;
    }

    /**
     * {@linkplain #mergeProperties Merge}, {@linkplain #convertProperties convert} and
     * {@linkplain #processProperties process} properties against the given bean factory.
     * @throws BeanInitializationException if any properties cannot be loaded
     */
    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        try {
            Properties mergedProps = mergeProperties();

            // Convert the merged properties, if necessary.
            convertProperties(mergedProps);

            // Let the subclass process the properties.
            processProperties(beanFactory, mergedProps);
        } catch (IOException ex) {
            throw new BeanInitializationException("Could not load properties", ex);
        }
    }

    /**
     * Convert the given merged properties, converting property values
     * if necessary. The result will then be processed.
     * <p>The default implementation will invoke {@link #convertPropertyValue}
     * for each property value, replacing the original with the converted value.
     * @param props the Properties to convert
     * @see #processProperties
     */
    protected void convertProperties(Properties props) {
        Enumeration<?> propertyNames = props.propertyNames();
        while (propertyNames.hasMoreElements()) {
            String propertyName = (String) propertyNames.nextElement();
            String propertyValue = props.getProperty(propertyName);
            String convertedValue = convertProperty(propertyName, propertyValue);
            if (!ObjectUtils.nullSafeEquals(propertyValue, convertedValue)) {
                props.setProperty(propertyName, convertedValue);
            }
        }
    }

    /**
     * Convert the given property from the properties source to the value
     * which should be applied.
     * <p>The default implementation calls {@link #convertPropertyValue(String)}.
     * @param propertyName the name of the property that the value is defined for
     * @param propertyValue the original value from the properties source
     * @return the converted value, to be used for processing
     * @see #convertPropertyValue(String)
     */
    protected String convertProperty(String propertyName, String propertyValue) {
        return convertPropertyValue(propertyValue);
    }

    /**
     * Convert the given property value from the properties source to the value
     * which should be applied.
     * <p>The default implementation simply returns the original value.
     * Can be overridden in subclasses, for example to detect
     * encrypted values and decrypt them accordingly.
     * @param originalValue the original value from the properties source
     * (properties file or local "properties")
     * @return the converted value, to be used for processing
     * @see #setProperties
     * @see #setLocations
     * @see #setLocation
     * @see #convertProperty(String, String)
     */
    protected String convertPropertyValue(String originalValue) {
        return originalValue;
    }

    /**
     * Apply the given Properties to the given BeanFactory.
     * @param beanFactory the BeanFactory used by the application context
     * @param props the Properties to apply
     * @throws org.springframework.beans.BeansException in case of errors
     */
    protected abstract void processProperties(ConfigurableListableBeanFactory beanFactory, Properties props)
            throws BeansException;

}