Shiro源码(三)——Spring整合Shiro启动流程源码分析

Spring整合shiro后，shiro是通过ShiroFilterFactoryBean加入到Spring容器中的，下面看其源码:

public class ShiroFilterFactoryBean implements FactoryBean, BeanPostProcessor

可以看到，它实现了FactoryBean接口和BeanPostProcessor接口。下面看这两个接口的实现方法:

public Object getObject() throws Exception {
        if (instance == null) {
            instance = createInstance();
        }
        return instance;
    }

getObject方法将instance返回到了Spring容器中，instance对象是:

private AbstractShiroFilter instance;

是一个ShiroFilter。下面看createInstance()方法，看AbstractShiroFilter对象是如何创建出来的。

protected AbstractShiroFilter createInstance() throws Exception {

        log.debug("Creating Shiro Filter instance.");

        SecurityManager securityManager = getSecurityManager();
        if (securityManager == null) {
            String msg = "SecurityManager property must be set.";
            throw new BeanInitializationException(msg);
        }

        if (!(securityManager instanceof WebSecurityManager)) {
            String msg = "The security manager does not implement the WebSecurityManager interface.";
            throw new BeanInitializationException(msg);
        }

        FilterChainManager manager = createFilterChainManager();

        //Expose the constructed FilterChainManager by first wrapping it in a
        // FilterChainResolver implementation. The AbstractShiroFilter implementations
        // do not know about FilterChainManagers - only resolvers:
        PathMatchingFilterChainResolver chainResolver = new PathMatchingFilterChainResolver();
        chainResolver.setFilterChainManager(manager);

        //Now create a concrete ShiroFilter instance and apply the acquired SecurityManager and built
        //FilterChainResolver.  It doesn't matter that the instance is an anonymous inner class
        //here - we're just using it because it is a concrete AbstractShiroFilter instance that accepts
        //injection of the SecurityManager and FilterChainResolver:
        return new SpringShiroFilter((WebSecurityManager) securityManager, chainResolver);
    }

这段代码的重点在:

FilterChainManager manager = createFilterChainManager();

这个方法创建了拦截器链，Shiro的权限控制都是靠一系列拦截器实现的，通过debug，看有哪些默认的拦截器链。
首先，manager对象有三个属性:filterConfig，filters和filterChains。看filters里有哪些内容:

可以看到，里面存放了shiro默认的filter和我们程序中自定义的filter。
再看filterChains中的内容:

可以看到，里面存放的是我们配置的资源权限认证映射，filterChains是一个linkedHashMap，key是资源，value是过滤器拦截链，即这个资源，需要经过哪些filters过滤，如下图所示:

分析到这里，有两个疑问:1.shiro的默认filter都是什么作用? 2.filterChains中每个资源的filtersChain个数都不一样,是如何判断哪个资源用哪个filter的？
这样，shiro中的过滤器就加入到了Spring容器中。分析完如何加入Spring容器的，我们分析上面提到的两点疑问。