org.springframework.web.method.ControllerAdviceBean.java Source code

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/*
 * Copyright 2002-2014 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.web.method;

import java.lang.annotation.Annotation;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

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

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryUtils;
import org.springframework.context.ApplicationContext;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.core.annotation.OrderUtils;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.StringUtils;
import org.springframework.web.bind.annotation.ControllerAdvice;

/**
 * Encapsulates information about an {@linkplain ControllerAdvice @ControllerAdvice}
 * Spring-managed bean without necessarily requiring it to be instantiated.
 *
 * <p>The {@link #findAnnotatedBeans(ApplicationContext)} method can be used to discover
 * such beans. However, an {@code ControllerAdviceBean} may be created from
 * any object, including ones without an {@code @ControllerAdvice}.
 *
 * @author Rossen Stoyanchev
 * @author Brian Clozel
 * @since 3.2
 */
public class ControllerAdviceBean implements Ordered {

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

    private final Object bean;

    private final int order;

    private final BeanFactory beanFactory;

    private final List<Package> basePackages = new ArrayList<Package>();

    private final List<Class<? extends Annotation>> annotations = new ArrayList<Class<? extends Annotation>>();

    private final List<Class<?>> assignableTypes = new ArrayList<Class<?>>();

    /**
     * Create an instance using the given bean name.
     * @param beanName the name of the bean
     * @param beanFactory a BeanFactory that can be used later to resolve the bean
     */
    public ControllerAdviceBean(String beanName, BeanFactory beanFactory) {
        Assert.hasText(beanName, "Bean name must not be null");
        Assert.notNull(beanFactory, "BeanFactory must not be null");

        if (!beanFactory.containsBean(beanName)) {
            throw new IllegalArgumentException(
                    "BeanFactory [" + beanFactory + "] does not contain bean with name '" + beanName + "'");
        }

        this.bean = beanName;
        this.beanFactory = beanFactory;

        Class<?> beanType = this.beanFactory.getType(beanName);
        this.order = initOrderFromBeanType(beanType);

        ControllerAdvice annotation = AnnotationUtils.findAnnotation(beanType, ControllerAdvice.class);
        Assert.notNull(annotation, "BeanType [" + beanType.getName() + "] is not annotated @ControllerAdvice");

        this.basePackages.addAll(initBasePackagesFromBeanType(beanType, annotation));
        this.annotations.addAll(Arrays.asList(annotation.annotations()));
        this.assignableTypes.addAll(Arrays.asList(annotation.assignableTypes()));
    }

    /**
     * Create an instance using the given bean instance.
     * @param bean the bean
     */
    public ControllerAdviceBean(Object bean) {
        Assert.notNull(bean, "Bean must not be null");
        this.bean = bean;
        this.order = initOrderFromBean(bean);

        Class<?> beanType = bean.getClass();
        ControllerAdvice annotation = AnnotationUtils.findAnnotation(beanType, ControllerAdvice.class);
        Assert.notNull(annotation, "Bean type [" + beanType.getName() + "] is not annotated @ControllerAdvice");

        this.basePackages.addAll(initBasePackagesFromBeanType(beanType, annotation));
        this.annotations.addAll(Arrays.asList(annotation.annotations()));
        this.assignableTypes.addAll(Arrays.asList(annotation.assignableTypes()));
        this.beanFactory = null;
    }

    /**
     * Returns the order value extracted from the {@link ControllerAdvice}
     * annotation or {@link Ordered#LOWEST_PRECEDENCE} otherwise.
     */
    @Override
    public int getOrder() {
        return this.order;
    }

    /**
     * Returns the type of the contained bean.
     * If the bean type is a CGLIB-generated class, the original, user-defined class is returned.
     */
    public Class<?> getBeanType() {
        Class<?> clazz = (this.bean instanceof String ? this.beanFactory.getType((String) this.bean)
                : this.bean.getClass());
        return ClassUtils.getUserClass(clazz);
    }

    /**
     * Return a bean instance if necessary resolving the bean name through the BeanFactory.
     */
    public Object resolveBean() {
        return (this.bean instanceof String ? this.beanFactory.getBean((String) this.bean) : this.bean);
    }

    /**
     * Checks whether the given bean type should be assisted by this
     * {@code @ControllerAdvice} instance.
     * @param beanType the type of the bean to check
     * @see org.springframework.web.bind.annotation.ControllerAdvice
     * @since 4.0
     */
    public boolean isApplicableToBeanType(Class<?> beanType) {
        if (!hasSelectors()) {
            return true;
        } else if (beanType != null) {
            for (Class<?> clazz : this.assignableTypes) {
                if (ClassUtils.isAssignable(clazz, beanType)) {
                    return true;
                }
            }
            for (Class<? extends Annotation> annotationClass : this.annotations) {
                if (AnnotationUtils.findAnnotation(beanType, annotationClass) != null) {
                    return true;
                }
            }
            String packageName = beanType.getPackage().getName();
            for (Package basePackage : this.basePackages) {
                if (packageName.startsWith(basePackage.getName())) {
                    return true;
                }
            }
        }
        return false;
    }

    private boolean hasSelectors() {
        return (!this.basePackages.isEmpty() || !this.annotations.isEmpty() || !this.assignableTypes.isEmpty());
    }

    @Override
    public boolean equals(Object other) {
        return (this == other || (other instanceof ControllerAdviceBean
                && this.bean.equals(((ControllerAdviceBean) other).bean)));
    }

    @Override
    public int hashCode() {
        return this.bean.hashCode();
    }

    @Override
    public String toString() {
        return this.bean.toString();
    }

    /**
     * Find the names of beans annotated with
     * {@linkplain ControllerAdvice @ControllerAdvice} in the given
     * ApplicationContext and wrap them as {@code ControllerAdviceBean} instances.
     */
    public static List<ControllerAdviceBean> findAnnotatedBeans(ApplicationContext applicationContext) {
        List<ControllerAdviceBean> beans = new ArrayList<ControllerAdviceBean>();
        for (String name : BeanFactoryUtils.beanNamesForTypeIncludingAncestors(applicationContext, Object.class)) {
            if (applicationContext.findAnnotationOnBean(name, ControllerAdvice.class) != null) {
                beans.add(new ControllerAdviceBean(name, applicationContext));
            }
        }
        return beans;
    }

    private static int initOrderFromBean(Object bean) {
        return (bean instanceof Ordered ? ((Ordered) bean).getOrder() : initOrderFromBeanType(bean.getClass()));
    }

    private static int initOrderFromBeanType(Class<?> beanType) {
        return OrderUtils.getOrder(beanType, Ordered.LOWEST_PRECEDENCE);
    }

    private static List<Package> initBasePackagesFromBeanType(Class<?> beanType, ControllerAdvice annotation) {
        List<Package> basePackages = new ArrayList<Package>();
        List<String> basePackageNames = new ArrayList<String>();
        basePackageNames.addAll(Arrays.asList(annotation.value()));
        basePackageNames.addAll(Arrays.asList(annotation.basePackages()));
        for (String pkgName : basePackageNames) {
            if (StringUtils.hasText(pkgName)) {
                Package pkg = Package.getPackage(pkgName);
                if (pkg != null) {
                    basePackages.add(pkg);
                } else {
                    logger.warn("Package [" + pkgName + "] was not found, see [" + beanType.getName() + "]");
                }
            }
        }
        for (Class<?> markerClass : annotation.basePackageClasses()) {
            Package pack = markerClass.getPackage();
            if (pack != null) {
                basePackages.add(pack);
            } else {
                logger.warn("Package was not found for class [" + markerClass.getName() + "], see ["
                        + beanType.getName() + "]");
            }
        }
        return basePackages;
    }

}