org.wallride.autoconfigure.WebGuestComponentScanRegistrar.java Source code

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Here is the source code for org.wallride.autoconfigure.WebGuestComponentScanRegistrar.java

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/*
 * Copyright 2014 Tagbangers, Inc.
 *
 * 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.wallride.autoconfigure;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.SmartInitializingSingleton;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.beans.factory.config.ConstructorArgumentValues;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.GenericBeanDefinition;
import org.springframework.boot.autoconfigure.web.DispatcherServletAutoConfiguration;
import org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext;
import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.AnnotationAttributes;
import org.springframework.core.type.AnnotationMetadata;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.ObjectUtils;
import org.springframework.web.servlet.DispatcherServlet;

import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.Set;

public class WebGuestComponentScanRegistrar implements ImportBeanDefinitionRegistrar {

    private static final String BEAN_NAME = "webGuestComponentScanBeanPostProcessor";

    @Override
    public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata,
            BeanDefinitionRegistry registry) {
        Set<String> packagesToScan = getPackagesToScan(importingClassMetadata);
        if (!registry.containsBeanDefinition(BEAN_NAME)) {
            addWebGuestComponentScanBeanPostProcessor(registry, packagesToScan);
        } else {
            updateWebGuestComponentScanBeanPostProcessor(registry, packagesToScan);
        }
    }

    private Set<String> getPackagesToScan(AnnotationMetadata metadata) {
        AnnotationAttributes attributes = AnnotationAttributes
                .fromMap(metadata.getAnnotationAttributes(WebGuestComponentScan.class.getName()));
        String[] value = attributes.getStringArray("value");
        String[] basePackages = attributes.getStringArray("basePackages");
        Class<?>[] basePackageClasses = attributes.getClassArray("basePackageClasses");
        if (!ObjectUtils.isEmpty(value)) {
            Assert.state(ObjectUtils.isEmpty(basePackages),
                    "@WebGuestComponentScan basePackages and value attributes are mutually exclusive");
        }
        Set<String> packagesToScan = new LinkedHashSet<String>();
        packagesToScan.addAll(Arrays.asList(value));
        packagesToScan.addAll(Arrays.asList(basePackages));
        for (Class<?> basePackageClass : basePackageClasses) {
            packagesToScan.add(ClassUtils.getPackageName(basePackageClass));
        }
        if (packagesToScan.isEmpty()) {
            return Collections.singleton(ClassUtils.getPackageName(metadata.getClassName()));
        }
        return packagesToScan;
    }

    private void addWebGuestComponentScanBeanPostProcessor(BeanDefinitionRegistry registry,
            Set<String> packagesToScan) {
        GenericBeanDefinition beanDefinition = new GenericBeanDefinition();
        beanDefinition.setBeanClass(WebGuestComponentScanBeanPostProcessor.class);
        beanDefinition.getConstructorArgumentValues().addGenericArgumentValue(toArray(packagesToScan));
        beanDefinition.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
        // We don't need this one to be post processed otherwise it can cause a
        // cascade of bean instantiation that we would rather avoid.
        beanDefinition.setSynthetic(true);
        registry.registerBeanDefinition(BEAN_NAME, beanDefinition);
    }

    private void updateWebGuestComponentScanBeanPostProcessor(BeanDefinitionRegistry registry,
            Set<String> packagesToScan) {
        BeanDefinition definition = registry.getBeanDefinition(BEAN_NAME);
        ConstructorArgumentValues.ValueHolder constructorArguments = definition.getConstructorArgumentValues()
                .getGenericArgumentValue(String[].class);
        Set<String> mergedPackages = new LinkedHashSet<>();
        mergedPackages.addAll(Arrays.asList((String[]) constructorArguments.getValue()));
        mergedPackages.addAll(packagesToScan);
        constructorArguments.setValue(toArray(mergedPackages));
    }

    private String[] toArray(Set<String> set) {
        return set.toArray(new String[set.size()]);
    }

    static class WebGuestComponentScanBeanPostProcessor
            implements BeanPostProcessor, SmartInitializingSingleton, Ordered {

        private final String[] packagesToScan;

        private boolean processed;

        WebGuestComponentScanBeanPostProcessor(String[] packagesToScan) {
            this.packagesToScan = packagesToScan;
        }

        @Override
        public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
            if (DispatcherServletAutoConfiguration.DEFAULT_DISPATCHER_SERVLET_BEAN_NAME.equals(beanName)) {
                DispatcherServlet dispatcherServlet = (DispatcherServlet) bean;
                AnnotationConfigEmbeddedWebApplicationContext context = (AnnotationConfigEmbeddedWebApplicationContext) dispatcherServlet
                        .getWebApplicationContext();
                context.scan(packagesToScan);
                this.processed = true;
            }
            return bean;
        }

        @Override
        public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
            return bean;
        }

        @Override
        public void afterSingletonsInstantiated() {
            Assert.state(this.processed,
                    "Unable to configure " + "LocalContainerEntityManagerFactoryBean from @WebGuestComponentScan, "
                            + "ensure an appropriate bean is registered.");
        }

        @Override
        public int getOrder() {
            return 0;
        }
    }
}