/*
* Copyright 2012-2013 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.boot.context.config;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import org.springframework.beans.BeanUtils;
import org.springframework.context.ApplicationContextException;
import org.springframework.context.ApplicationContextInitializer;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.core.GenericTypeResolver;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.AnnotationAwareOrderComparator;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.StringUtils;
/**
* {@link ApplicationContextInitializer} that delegates to other initializers that are
* specified under a {@literal context.initializer.classes} environment property.
*
* @author Dave Syer
* @author Phillip Webb
*/
public class DelegatingApplicationContextInitializer implements
ApplicationContextInitializer<ConfigurableApplicationContext>, Ordered {
// NOTE: Similar to org.springframework.web.context.ContextLoader
private static final String PROPERTY_NAME = "context.initializer.classes";
private int order = 0;
@Override
public void initialize(ConfigurableApplicationContext context) {
ConfigurableEnvironment environment = context.getEnvironment();
List<Class<?>> initializerClasses = getInitializerClasses(environment);
if (initializerClasses.size() > 0) {
applyInitializerClasses(context, initializerClasses);
}
}
private List<Class<?>> getInitializerClasses(ConfigurableEnvironment env) {
String classNames = env.getProperty(PROPERTY_NAME);
List<Class<?>> classes = new ArrayList<Class<?>>();
if (StringUtils.hasLength(classNames)) {
for (String className : StringUtils.tokenizeToStringArray(classNames, ",")) {
classes.add(getInitializerClass(className));
}
}
return classes;
}
private Class<?> getInitializerClass(String className) throws LinkageError {
try {
Class<?> initializerClass = ClassUtils.forName(className,
ClassUtils.getDefaultClassLoader());
Assert.isAssignable(ApplicationContextInitializer.class, initializerClass);
return initializerClass;
}
catch (ClassNotFoundException ex) {
throw new ApplicationContextException(
"Failed to load context initializer class [" + className + "]", ex);
}
}
private void applyInitializerClasses(ConfigurableApplicationContext context,
List<Class<?>> initializerClasses) {
Class<?> contextClass = context.getClass();
List<ApplicationContextInitializer<?>> initializers = new ArrayList<ApplicationContextInitializer<?>>();
for (Class<?> initializerClass : initializerClasses) {
initializers.add(instantiateInitializer(contextClass, initializerClass));
}
applyInitializers(context, initializers);
}
private ApplicationContextInitializer<?> instantiateInitializer(
Class<?> contextClass, Class<?> initializerClass) {
Class<?> requireContextClass = GenericTypeResolver.resolveTypeArgument(
initializerClass, ApplicationContextInitializer.class);
Assert.isAssignable(requireContextClass, contextClass, String.format(
"Could not add context initializer [%s]"
+ " as its generic parameter [%s] is not assignable "
+ "from the type of application context used by this "
+ "context loader [%s]: ", initializerClass.getName(),
requireContextClass.getName(), contextClass.getName()));
return (ApplicationContextInitializer<?>) BeanUtils
.instantiateClass(initializerClass);
}
@SuppressWarnings({ "unchecked", "rawtypes" })
private void applyInitializers(ConfigurableApplicationContext context,
List<ApplicationContextInitializer<?>> initializers) {
Collections.sort(initializers, new AnnotationAwareOrderComparator());
for (ApplicationContextInitializer initializer : initializers) {
initializer.initialize(context);
}
}
public void setOrder(int order) {
this.order = order;
}
@Override
public int getOrder() {
return this.order;
}
}