org.springframework.boot.context.ConfigurationWarningsApplicationContextInitializer.java Source code

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Here is the source code for org.springframework.boot.context.ConfigurationWarningsApplicationContextInitializer.java

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/*
 * Copyright 2012-2015 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;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.annotation.AnnotatedBeanDefinition;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.BeanDefinitionRegistryPostProcessor;
import org.springframework.context.ApplicationContextInitializer;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.core.Ordered;
import org.springframework.core.PriorityOrdered;
import org.springframework.core.annotation.AnnotationAttributes;
import org.springframework.core.type.AnnotationMetadata;
import org.springframework.util.ClassUtils;
import org.springframework.util.ObjectUtils;
import org.springframework.util.StringUtils;

/**
 * {@link ApplicationContextInitializer} to report warnings for common misconfiguration
 * mistakes.
 *
 * @author Phillip Webb
 * @since 1.2.0
 */
public class ConfigurationWarningsApplicationContextInitializer
        implements ApplicationContextInitializer<ConfigurableApplicationContext> {

    private static Log logger = LogFactory.getLog(ConfigurationWarningsApplicationContextInitializer.class);

    @Override
    public void initialize(ConfigurableApplicationContext context) {
        context.addBeanFactoryPostProcessor(new ConfigurationWarningsPostProcessor(getChecks()));
    }

    /**
     * Returns the checks that should be applied.
     * @return the checks to apply
     */
    protected Check[] getChecks() {
        return new Check[] { new ComponentScanDefaultPackageCheck() };
    }

    /**
     * {@link BeanDefinitionRegistryPostProcessor} to report warnings.
     */
    protected final static class ConfigurationWarningsPostProcessor
            implements PriorityOrdered, BeanDefinitionRegistryPostProcessor {

        private Check[] checks;

        public ConfigurationWarningsPostProcessor(Check[] checks) {
            this.checks = checks;
        }

        @Override
        public int getOrder() {
            return Ordered.LOWEST_PRECEDENCE - 1;
        }

        @Override
        public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        }

        @Override
        public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
            for (Check check : this.checks) {
                String message = check.getWarning(registry);
                if (StringUtils.hasLength(message)) {
                    warn(message);
                }
            }

        }

        private void warn(String message) {
            if (logger.isWarnEnabled()) {
                logger.warn("\n\n** WARNING ** : " + message + "\n\n");
            }
        }

    }

    /**
     * A single check that can be applied.
     */
    protected interface Check {

        /**
         * Returns a warning if the check fails or {@code null} if there are no problems.
         * @param registry the {@link BeanDefinitionRegistry}
         * @return a warning message or {@code null}
         */
        String getWarning(BeanDefinitionRegistry registry);

    }

    /**
     * {@link Check} for {@code @ComponentScan} on the default package.
     */
    protected static class ComponentScanDefaultPackageCheck implements Check {

        @Override
        public String getWarning(BeanDefinitionRegistry registry) {
            if (isComponentScanningDefaultPackage(registry)) {
                return "Your ApplicationContext is unlikely to start due to a "
                        + "@ComponentScan of the default package.";
            }
            return null;
        }

        private boolean isComponentScanningDefaultPackage(BeanDefinitionRegistry registry) {
            String[] names = registry.getBeanDefinitionNames();
            for (String name : names) {
                BeanDefinition definition = registry.getBeanDefinition(name);
                if (definition instanceof AnnotatedBeanDefinition) {
                    AnnotatedBeanDefinition annotatedDefinition = (AnnotatedBeanDefinition) definition;
                    if (isScanningDefaultPackage(annotatedDefinition.getMetadata())) {
                        return true;
                    }
                }
            }
            return false;
        }

        private boolean isScanningDefaultPackage(AnnotationMetadata metadata) {
            AnnotationAttributes attributes = AnnotationAttributes
                    .fromMap(metadata.getAnnotationAttributes(ComponentScan.class.getName(), true));
            if (attributes != null && hasNoScanPackageSpecified(attributes)) {
                if (isInDefaultPackage(metadata.getClassName())) {
                    return true;
                }
            }
            return false;
        }

        private boolean hasNoScanPackageSpecified(AnnotationAttributes attributes) {
            return isAllEmpty(attributes, "value", "basePackages", "basePackageClasses");
        }

        private boolean isAllEmpty(AnnotationAttributes attributes, String... names) {
            for (String name : names) {
                if (!ObjectUtils.isEmpty(attributes.getStringArray(name))) {
                    return false;
                }
            }
            return true;
        }

        protected boolean isInDefaultPackage(String className) {
            String packageName = ClassUtils.getPackageName(className);
            return StringUtils.isEmpty(packageName);
        }
    }

}