shiro与spring整合的流程

首先需要在web.xml文件中配置以下的过滤器进行拦截请求

<filter>
        <filter-name>shiroFilter</filter-name>
        <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
        <init-param>
            <param-name>targetFilterLifecycle</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>shiroFilter</filter-name>
        <url-pattern>/admin/*</url-pattern>
    </filter-mapping>

然后在spring的配置文件中配置ShiroFilterFactoryBean

<bean id="adminShiroFilter" class="org.apache.shiro.spring.web.ShiroFilterFactoryBean">
        <property name="securityManager" ref="adminSecurityManager" />
        <property name="unauthorizedUrl" value="/admin/system/unauthorized.do" />
        <property name="filterChainDefinitions">
            <value>
                    /admin/** = authc
            </value>
        </property>
        <property name="filters">
            <map>
                <entry key="authc" value-ref="authenticationFilter" />
            </map>
        </property>
    </bean>

当请求的url以“/admin”开头的都会被这个过滤器拦截，然后交给shiro来处理。由于本文不是解析shiro的执行流程，而是侧重解析shiro是如何整合到spring中，并由spring进行管理的。所以下面将对shiro和spring如何整合进行源码的解析。

ShiroFilterFactoryBean的原理

首先，从上面的spring的配置文件中可以看到一个很显眼的bean，也就是ShiroFilterFactoryBean。这个以...FactoryBean结尾的bean，在spring中很自然想到：这是spring用于整合第三方框架所留的扩展。
下面来分析一下这个bean是如何运作的
首先，spring容器实例化bean时，会调用getBean（）方法。
进到org.springframework.beans.factory.support.AbstractBeanFactory类的doGetBean（）方法中

@SuppressWarnings("unchecked")
    protected <T> T doGetBean(
            final String name, final Class<T> requiredType, final Object[] args, boolean typeCheckOnly)
            throws BeansException {
                 。。。。
        //省略前面的代码
        Object sharedInstance = getSingleton(beanName);
        if (sharedInstance != null && args == null) {
            if (logger.isDebugEnabled()) {
                if (isSingletonCurrentlyInCreation(beanName)) {
                    logger.debug("Returning eagerly cached instance of singleton bean '" + beanName +
                            "' that is not fully initialized yet - a consequence of a circular reference");
                }
                else {
                    logger.debug("Returning cached instance of singleton bean '" + beanName + "'");
                }
            }
                    //这里将执行实现了FactoryBean接口的类
            bean = getObjectForBeanInstance(sharedInstance, name, beanName, null);
        }
              //省略后面的代码
        return (T) bean;
    }

从上面的代码可以看出，真正执行ShiroFilterFactoryBean的是getObjectForBeanInstance(sharedInstance, name, beanName, mbd);方法。
最终将调用下面org.springframework.beans.factory.support.FactoryBeanRegistrySupport类的doGetObjectFromFactoryBean方法：

private Object doGetObjectFromFactoryBean(final FactoryBean<?> factory, final String beanName)
            throws BeanCreationException {
        Object object;
        try {
                  .....省略
//通过factory.getObject（）方法来初始化一些配置信息
            object = factory.getObject();
            
        }       
        return object;
    }

从上面的代码可以看出最终调用ShiroFilterFactoryBean类的getObject方法，代码如下

   public Object getObject() throws Exception {
        if (instance == null) {
            instance = createInstance();
        }
        return instance;
    }
 protected AbstractShiroFilter createInstance() throws Exception { 
        SecurityManager securityManager = getSecurityManager(); 
        if (!(securityManager instanceof WebSecurityManager)) {
            String msg = "The security manager does not implement the WebSecurityManager interface.";
            throw new BeanInitializationException(msg);
        }
        FilterChainManager manager = createFilterChainManager();     
        PathMatchingFilterChainResolver chainResolver = new PathMatchingFilterChainResolver();
        chainResolver.setFilterChainManager(manager);      
        return new SpringShiroFilter((WebSecurityManager) securityManager, chainResolver);
    }

最终依赖注入一些属性，如securityManager ，FilterChain等，这样shiro就可以用了，当有请求来时，将根据url调用指定的过滤器进行拦截和校验。