Spring Security Config : SecurityConfigurerAdapter SecurityConfigurer缺省实现类

概述

介绍

SecurityConfigurerAdapter是Spring Security Config对概念模型接口SecurityConfigurer所提供的缺省实现。它作为一个基类存在，开发人员想实现一个SecurityConfigurer时，可以继承自SecurityConfigurerAdapter,然后仅仅覆盖实现其中感兴趣的方法。具体来讲,SecurityConfigurerAdapter提供了如下功能:

• SecurityConfigurer接口所定义的方法的缺省实现
  • #init
  • #configure
• 设置和获取所要被配置的安全构建器
  • #setBuilder
  • #getBuilder
• 设置配置过程中对新建安全对象的后置处理器
  • #addObjectPostProcessor
• 链式配置构建的支持方法
  • #and

继承关系

源代码

源代码版本 : Spring Security Config 5.1.4.RELEASE

package org.springframework.security.config.annotation;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import org.springframework.core.GenericTypeResolver;
import org.springframework.core.annotation.AnnotationAwareOrderComparator;

/**
 * A base class for SecurityConfigurer that allows subclasses to only implement
 * the methods they are interested in. It also provides a mechanism for using the
 * SecurityConfigurer and when done gaining access to the SecurityBuilder
 * that is being configured.
 *
 * @author Rob Winch
 * @author Wallace Wadge
 *
 * @param <O> The Object being built by B 构建器B所要构建目标对象
 * @param <B> The Builder that is building O and is configured by
 * SecurityConfigurerAdapter 构建器
 */
public abstract class SecurityConfigurerAdapter<O, B extends SecurityBuilder<O>>
		implements SecurityConfigurer<O, B> {
	private B securityBuilder;

    // 配置过程中新建的安全对象的后置处理器，该对象是多个ObjectPostProcessor的组合
    // 缺省情况下该后置处理器中不包含任何 ObjectPostProcessor
	private CompositeObjectPostProcessor objectPostProcessor = new CompositeObjectPostProcessor();

    // 空方法，留给子类实现
	public void init(B builder) throws Exception {
	}

    // 空方法，留给子类实现
	public void configure(B builder) throws Exception {
	}

	/**
	 * Return the SecurityBuilder when done using the SecurityConfigurer.
	 * This is useful for method chaining.
	 * 用于支持链式构建，返回目标构建器
	 * @return the SecurityBuilder for further customizations
	 */
	public B and() {
		return getBuilder();
	}

	/**
	 * Gets the SecurityBuilder. Cannot be null.
	 *
	 * @return the SecurityBuilder
	 * @throws IllegalStateException if SecurityBuilder is null
	 */
	protected final B getBuilder() {
		if (securityBuilder == null) {
			throw new IllegalStateException("securityBuilder cannot be null");
		}
		return securityBuilder;
	}

	/**
	 * Performs post processing of an object. The default is to delegate to the
	 * ObjectPostProcessor.
	 *
	 * @param object the Object to post process
	 * @return the possibly modified Object to use
	 */
	@SuppressWarnings("unchecked")
	protected <T> T postProcess(T object) {
		return (T) this.objectPostProcessor.postProcess(object);
	}

	/**
	 * Adds an ObjectPostProcessor to be used for this
	 * SecurityConfigurerAdapter. The default implementation does nothing to the
	 * object.
	 *
	 * @param objectPostProcessor the ObjectPostProcessor to use
	 */
	public void addObjectPostProcessor(ObjectPostProcessor<?> objectPostProcessor) {
		this.objectPostProcessor.addObjectPostProcessor(objectPostProcessor);
	}

	/**
	 * Sets the SecurityBuilder to be used. This is automatically set when using
	 * AbstractConfiguredSecurityBuilder#apply(SecurityConfigurerAdapter)
	 *
	 * @param builder the SecurityBuilder to set
	 */
	public void setBuilder(B builder) {
		this.securityBuilder = builder;
	}

	/**
	 * An ObjectPostProcessor that delegates work to numerous
	 * ObjectPostProcessor implementations.
	 *
     * 嵌套类，使用组合模式实现了接口 ObjectPostProcessor，用于组合多个 ObjectPostProcessor，
     * 当使用该组合对象对目标对象进行后置处理时，其实是使用所组合的每个 ObjectPostProcessor 依次
     * 对目标对象进行后置处理
	 * @author Rob Winch
	 */
	private static final class CompositeObjectPostProcessor implements
			ObjectPostProcessor<Object> {
		private List<ObjectPostProcessor<? extends Object>> postProcessors = 
			new ArrayList<ObjectPostProcessor<?>>();

		@SuppressWarnings({ "rawtypes", "unchecked" })
		public Object postProcess(Object object) {
			for (ObjectPostProcessor opp : postProcessors) {
				Class<?> oppClass = opp.getClass();
				Class<?> oppType = GenericTypeResolver.resolveTypeArgument(oppClass,
						ObjectPostProcessor.class);
				if (oppType == null || oppType.isAssignableFrom(object.getClass())) {
					object = opp.postProcess(object);
				}
			}
			return object;
		}

		/**
		 * Adds an ObjectPostProcessor to use
		 * @param objectPostProcessor the ObjectPostProcessor to add
		 * @return true if the ObjectPostProcessor was added, else false
		 */
		private boolean addObjectPostProcessor(
				ObjectPostProcessor<? extends Object> objectPostProcessor) {
			boolean result = this.postProcessors.add(objectPostProcessor);
			Collections.sort(postProcessors, AnnotationAwareOrderComparator.INSTANCE);
			return result;
		}
	}
}

参考文章

• Spring Security Config : 概念模型接口 SecurityConfigurer
• Spring Security Config : AbstractConfiguredSecurityBuilder
• Spring Security : HTTP请求安全构建器 HttpSecurity