码迷,mamicode.com
首页 > 其他好文 > 详细

Shiro的Filter机制详解---源码分析

时间:2016-12-30 19:29:14      阅读:683      评论:0      收藏:0      [点我收藏+]

标签:throw   初始化   st3   img   它的   子类   oid   equal   pattern   

Shiro的Filter机制详解

首先从spring-shiro.xml的filter配置说起,先回答两个问题:

1, 为什么相同url规则,后面定义的会覆盖前面定义的(执行的时候只执行最后一个)。

2, 为什么两个url规则都可以匹配同一个url,只执行第一个呢。

 

下面分别从这两个问题入手,最终阅读源码得到解答。

问题一解答

相同url但定义在不同的行,后面覆盖前面

/usr/login.do=test3
/usr/login.do=test1,test2
不会执行test3的filter

要解答第一个问题,需要知道shiro(或者说是spring)是如何扫描这些url规则并保存的。

Web.xml配置shiro以及spring-shiro.xml的核心配置

在web.xml中定义shiroFilter
<filter>
        <filter-name>shiroFilter</filter-name>
        <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
        <init-param>
            <!-- 该值缺省为false,表示生命周期由SpringApplicationContext管理,设置为true则表示由ServletContainer管理 -->
            <param-name>targetFilterLifecycle</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>shiroFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
在spring-shiro.xml中定义shiroFilter

(要和web.xml中的名称一样,因为spring就是依靠名称来获取这个bean的) 

<bean id="shiroFilter" class="org.apache.shiro.spring.web.ShiroFilterFactoryBean">
        <property name="securityManager" ref="securityManager" />
        <property name="loginUrl" value="/login.jsp" />
        <property name="unauthorizedUrl" value="/WEB-INF/405.html" />
        <property name="filters">
            <map>
                <entry key="kickout" value-ref="kickoutSessionControlFilter" />
            </map>
        </property>
        <property name="filterChainDefinitions">
            <value>
                /**=kickout
                /usr/login.do=anon
                /security/*=anon
                /usr/login.do=authc
                /usr/test/*=authc
            </value>
        </property>
    </bean>

都定义好之后,分析org.springframework.web.filter.DelegatingFilterProxy发现该filter类的任务是:将具体工作分派给org.apache.shiro.spring.web.ShiroFilterFactoryBean这个类中的静态内部类SpringShiroFilter做。

具体spring内部是怎么将工作委派的,暂时没有分析。

现在关注的是当spring把具体工作委派给ShiroFilterFactoryBean后,该类是怎么工作的。

Spring将配置注入到ShiroFilterFactoryBean

在这之前,spring通过bean注入,将ShiroFilterFactoryBean的相关成员通过set方法注入进去。

前面已经配置了filters和filterChainDefinitions,再次贴出如下所示:

<property name="filters">
            <map>
                <entry key="kickout" value-ref="kickoutSessionControlFilter" />
            </map>
        </property>
        <property name="filterChainDefinitions">
            <value>
                /**=kickout
                /usr/login.do=anon
                /security/*=anon
                /usr/login.do=authc
                /usr/test/*=authc
            </value>
        </property>

看一下ShiroFilterFactoryBean是怎么接收他们的。

 

Filters很简单,只需要map接收就自动完成了。

public void setFilters(Map<String, Filter> filters) {
        this.filters = filters;
    }

但是filterChainDefinitions是String类型的,需要转换(使用了ini转换方法,内部使用LinkedHashMap保存url和filter的映射关系,保证了顺序)

public void setFilterChainDefinitions(String definitions) {
        Ini ini = new Ini();
        ini.load(definitions);
        //did they explicitly state a ‘urls‘ section?  Not necessary, but just in case:
        Ini.Section section = ini.getSection(IniFilterChainResolverFactory.URLS);
        if (CollectionUtils.isEmpty(section)) {
            //no urls section.  Since this _is_ a urls chain definition property, just assume the
            //default section contains only the definitions:
            section = ini.getSection(Ini.DEFAULT_SECTION_NAME);
        }
        setFilterChainDefinitionMap(section);
    }

这两步完成后,filters被注入

filterChianDefinitions也被注入,但是注入方法通过shiro自定义了ini方式,

该方式通过LinkedHashMap保存url规则和对应的权限(键值对),所以当写了相同的url规则,后者会覆盖前者(------现在对HashMap的存储规则遗忘了,需要再看一下)

问题一解答完成

 

问题二解答:

同一个url可以匹配不同的规则,但只执行首行
/usr/* =test1,test2
/usr/login.do=test3
url = /usr/login.do请求来了,不会执行test3,因为已经匹配了/usr/* =test1,test2
要解答该问题,需要知道每个url的FilterChain是如何获取的

接上分析:

有了filter和filterChainDefinitionMap的数据后,下面的工作是构造FilterChainManager

构造FilterChainManager

为什么到这一步呢?

查看spring委托机制,最终找到ShiroFilterFactoryBeancreateInstance()方法(这个方法是shirofilter构造机制的主线),由于ShiroFilterFactoryBean 实现了FactoryBean,spring就是通过这个接口的createInstance方法获取到filter实例的,下面是该方法在ShiroFilterFactoryBean中的实现:

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();
       
        PathMatchingFilterChainResolver chainResolver = new PathMatchingFilterChainResolver();
        chainResolver.setFilterChainManager(manager);
       
        return new SpringShiroFilter((WebSecurityManager) securityManager, chainResolver);
    }

从这里可以知道,首先获取filterChainManager,具体方法如下

protected FilterChainManager createFilterChainManager() {
        DefaultFilterChainManager manager = new DefaultFilterChainManager();
        Map<String, Filter> defaultFilters = manager.getFilters();
        //apply global settings if necessary:
        for (Filter filter : defaultFilters.values()) {
            applyGlobalPropertiesIfNecessary(filter);
        }
        //Apply the acquired and/or configured filters:
        Map<String, Filter> filters = getFilters();
        if (!CollectionUtils.isEmpty(filters)) {
            for (Map.Entry<String, Filter> entry : filters.entrySet()) {
                String name = entry.getKey();
                Filter filter = entry.getValue();
                applyGlobalPropertiesIfNecessary(filter);
                if (filter instanceof Nameable) {
                    ((Nameable) filter).setName(name);
                }
                //‘init‘ argument is false, since Spring-configured filters should be initialized
                //in Spring (i.e. ‘init-method=blah‘) or implement InitializingBean:
                manager.addFilter(name, filter, false);
            }
        }
        //build up the chains:
        Map<String, String> chains = getFilterChainDefinitionMap();
        if (!CollectionUtils.isEmpty(chains)) {
            for (Map.Entry<String, String> entry : chains.entrySet()) {
                String url = entry.getKey();
                String chainDefinition = entry.getValue();
                manager.createChain(url, chainDefinition);
            }
        }
        return manager;
    }

分析后得知,首先在createFilterChainManager()方法中,创建一个DefaultFilterChainManager对象,而这个对象的构造函数在最后会将DefaultFilter中定义的shiro默认的filter映射加入到该对象中。如下代码就是DefaultFilter的定义。

 技术分享

在DefaultFilterChainManager中还做了一件事就是url-filter的映射变成filterChain,这句代码就是执行这个任务(将我们在xml文件中定义的filterChainDefinitions变成filterChain)。

manager.createChain(url, chainDefinition);

作用是将权限分割:如

"authc, roles[admin,user], perms[file:edit]"

将会被分割为

{ "authc", "roles[admin,user]", "perms[file:edit]" }

具体的源代码如下:

public void createChain(String chainName, String chainDefinition) {
      //。。。。。。。。

        //parse the value by tokenizing it to get the resulting filter-specific config entries
        //
        //e.g. for a value of
        //
        //     "authc, roles[admin,user], perms[file:edit]"
        //
        // the resulting token array would equal
        //
        //     { "authc", "roles[admin,user]", "perms[file:edit]" }
        //
        String[] filterTokens = splitChainDefinition(chainDefinition);
        for (String token : filterTokens) {
            String[] nameConfigPair = toNameConfigPair(token);
            addToChain(chainName, nameConfigPair[0], nameConfigPair[1]);
        }
    }

并且通过toNameConfigPair(token)将如:roles[admin,user]形式的变成rolesadmin,user形式的分割

然后根据url规则 映射 权限和角色

可以发现,每次分割一个token,都会通过addToChain方法接受

分析public void addToChain(String chainName, String filterName, String chainSpecificFilterConfig)方法

public void addToChain(String chainName, String filterName, String chainSpecificFilterConfig) {
        if (!StringUtils.hasText(chainName)) {
            throw new IllegalArgumentException("chainName cannot be null or empty.");
        }
        Filter filter = getFilter(filterName);
        if (filter == null) {
            throw new IllegalArgumentException("There is no filter with name ‘" + filterName +
                    "‘ to apply to chain [" + chainName + "] in the pool of available Filters.  Ensure a " +
                    "filter with that name/path has first been registered with the addFilter method(s).");
        }

        applyChainConfig(chainName, filter, chainSpecificFilterConfig);

        NamedFilterList chain = ensureChain(chainName);
        chain.add(filter);
    }

分析applyChainConfig(chainName, filter, chainSpecificFilterConfig);

protected void applyChainConfig(String chainName, Filter filter, String chainSpecificFilterConfig) {
      //………………………….
        if (filter instanceof PathConfigProcessor) {
            ((PathConfigProcessor) filter).processPathConfig(chainName, chainSpecificFilterConfig);
        } else {
            if (StringUtils.hasText(chainSpecificFilterConfig)) {
                //they specified a filter configuration, but the Filter doesn‘t implement PathConfigProcessor
                //this is an erroneous config:
                String msg = "chainSpecificFilterConfig was specified, but the underlying " +
                        "Filter instance is not an ‘instanceof‘ " +
                        PathConfigProcessor.class.getName() + ".  This is required if the filter is to accept " +
                        "chain-specific configuration.";
                throw new ConfigurationException(msg);
            }
        }
}

由于我们自定义的filter都是PathMatchingFilter的子类,所以在applyChainConfig方法中完成的就是将url添加到filter的url表中。

在PathMatchingFilter中可以发现

protected Map<String, Object> appliedPaths = new LinkedHashMap<String, Object>();

processPathConfig 方法的实现如下

public Filter processPathConfig(String path, String config) {
        String[] values = null;
        if (config != null) {
            values = split(config);
        }
        this.appliedPaths.put(path, values);
        return this;
}

基本上在spring-shiro.xml中定义filter的载入过程已经阅读完成,

1, 定义一个DefaultFilterChainManager对象

2, 首先加载默认的filter

3, 加载xml文件中定义的filter

4, 加载xml文件定义的url和filter映射关系

5, 将映射关系解析为以url为键,NamedFilterList为值的键值对。

6, 在解析的过程中,对每个url和对应的过滤条件,都会放到对应filter的appliedPaths中(在PathMatchingFilter中定义)。

现在FilterChainManager的对象已经创建完毕,并且每个filter也已经实例化完毕。

构造SpingShiroFilter

在创建SpringShiroFilter之前还要将刚才创建的FilterChainManager对象包装成一个PathMatchingFilterChainResolver对象(注释的意思是:不直接将FilterChainManager对象暴露给AbstractShiroFilter的实现者,在这里就是SpringShiroFilter。)

 技术分享

 

PathMatchingFilterChainResolver最重要的作用是:当请求url来的时候,他担任匹配工作(调用该类的getChain方法做匹配,暂时先不分析该方法,等知道在哪里调用该方法时候再分析。其实问题二此时已经可以解答,通过该方法就可以知道,某个url匹配到过滤链的第一个规则时就return了。

上图最后一句话执行完成后,一个SpringShiroFilter创建完毕。

请求过滤过程分析(上)

下面分析当url请求到来的时候,shiro是如何完成过滤的。首先通过图片大致的了解一下。

 技术分享

 

现在分析AbstractShiroFilter的doFilterInternal()方法

protected void doFilterInternal(ServletRequest servletRequest, ServletResponse servletResponse, final FilterChain chain)
            throws ServletException, IOException {
        Throwable t = null;
        try {
            final ServletRequest request = prepareServletRequest(servletRequest, servletResponse, chain);
            final ServletResponse response = prepareServletResponse(request, servletResponse, chain);
            final Subject subject = createSubject(request, response);
            subject.execute(new Callable() {
                public Object call() throws Exception {
                    updateSessionLastAccessTime(request, response);
                    executeChain(request, response, chain);
                    return null;
                }
            });
        } catch (ExecutionException ex) {
            t = ex.getCause();
        } catch (Throwable throwable) {
            t = throwable;
        }
        //…………
    }

暂时不关心subject相关的创建等过程,只关心这行代码

executeChain(request, response, chain);

具体实现如下

protected void executeChain(ServletRequest request, ServletResponse response, FilterChain origChain)
            throws IOException, ServletException {
        FilterChain chain = getExecutionChain(request, response, origChain);
        chain.doFilter(request, response);
}

再看getExecutionChain(request, response, origChain);具体实现如下:

protected FilterChain getExecutionChain(ServletRequest request, ServletResponse response, FilterChain origChain) {
        FilterChain chain = origChain;

        FilterChainResolver resolver = getFilterChainResolver();
        if (resolver == null) {
            log.debug("No FilterChainResolver configured.  Returning original FilterChain.");
            return origChain;
        }

        FilterChain resolved = resolver.getChain(request, response, origChain);
        if (resolved != null) {
            log.trace("Resolved a configured FilterChain for the current request.");
            chain = resolved;
        } else {
            log.trace("No FilterChain configured for the current request.  Using the default.");
        }

        return chain;
    }

可以发现,这里用到了我们在创建SpringShiroFilter时传递的FilterChainResolver,至此,我们终于找到了getChain()方法在这里被调用了。其源码实现如下

public FilterChain getChain(ServletRequest request, ServletResponse response, FilterChain originalChain) {
        FilterChainManager filterChainManager = getFilterChainManager();
        if (!filterChainManager.hasChains()) {
            return null;
        }

        String requestURI = getPathWithinApplication(request);

        //the ‘chain names‘ in this implementation are actually path patterns defined by the user.  We just use them
        //as the chain name for the FilterChainManager‘s requirements
        for (String pathPattern : filterChainManager.getChainNames()) {

            // If the path does match, then pass on to the subclass implementation for specific checks:
            if (pathMatches(pathPattern, requestURI)) {
                if (log.isTraceEnabled()) {
                    log.trace("Matched path pattern [" + pathPattern + "] for requestURI [" + requestURI + "].  " +
                            "Utilizing corresponding filter chain...");
                }
                return filterChainManager.proxy(originalChain, pathPattern);
            }
        }

        return null;
    }

从for循环可以看出,当匹配到第一个url规则,则return一个代表这个url规则的FilterChain给web容器执行。

 

问题二解答:每个url在匹配他的FilterChain时,当匹配到第一个URL规则时,就返回。

 

 

请求过滤过程分析(下)

FilterChain的实现类为org.apache.shiro.web.servlet.ProxiedFilterChain

从该类的doFilter方法可以知道,它会将Filter链的Filter的doFilter方法顺序执行一遍。下图展示了这一过程

技术分享

 

现在只需要分析每个Filter的doFilter方法就行了。

先看一下shiro整个filter框架继承关系(图片来自第八章 拦截器机制——《跟我学Shiro》)

 技术分享

上面是它的继承关系:最终的doFilter方法在OncePerRequestFilter中实现,具体代码如下:

public final void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain)
            throws ServletException, IOException {
        String alreadyFilteredAttributeName = getAlreadyFilteredAttributeName();
        if ( request.getAttribute(alreadyFilteredAttributeName) != null ) {
            log.trace("Filter ‘{}‘ already executed.  Proceeding without invoking this filter.", getName());
            filterChain.doFilter(request, response);
        } else //noinspection deprecation
            if (/* added in 1.2: */ !isEnabled(request, response) ||
                /* retain backwards compatibility: */ shouldNotFilter(request) ) {
            log.debug("Filter ‘{}‘ is not enabled for the current request.  Proceeding without invoking this filter.",
                    getName());
            filterChain.doFilter(request, response);
        } else {
            // Do invoke this filter...
            log.trace("Filter ‘{}‘ not yet executed.  Executing now.", getName());
            request.setAttribute(alreadyFilteredAttributeName, Boolean.TRUE);
            try {
                doFilterInternal(request, response, filterChain);
            } finally {
                // Once the request has finished, we‘re done and we don‘t
                // need to mark as ‘already filtered‘ any more.
                request.removeAttribute(alreadyFilteredAttributeName);
            }
        }
    }

可以发现该方法最终会调用doFilterInternal(request, response, filterChain);来完成具体的过滤操作,doFilterInternal方法在 SpringShiroFilter的直接父类AbstractShiroFilter的具体实现过程已经在上面分析过了:具体的就是shiro真正验证授权前的subject,session等初始化的工作,使得后面的过滤以及验证授权工作可以得到subject等然后正常工作。完成后调用其他shiro filter进行继续过滤

 

而除了shiroFilter之外,其余的filter都是AdviceFilter分支的子类。刚才看了AbstractShiroFilter的doFilterInternal方法,现在看一下AdviceFilter对该方法的实现:

public void doFilterInternal(ServletRequest request, ServletResponse response, FilterChain chain)
            throws ServletException, IOException {
        Exception exception = null;
        try {
            boolean continueChain = preHandle(request, response);
            if (log.isTraceEnabled()) {
                log.trace("Invoked preHandle method.  Continuing chain?: [" + continueChain + "]");
            }
            if (continueChain) {
                executeChain(request, response, chain);
            }
            postHandle(request, response);
            if (log.isTraceEnabled()) {
                log.trace("Successfully invoked postHandle method");
            }
        } catch (Exception e) {
            exception = e;
        } finally {
            cleanup(request, response, exception);
        }
    }

与AbstractShiroFilter的doFilterInternal方法不同的是,这里通过continueChain变量来判断到底后续的filter会不会被继续执行。而该变量的值由preHandle()函数决定。

 

基本上所有在系统中用到的filter都是继承PathMatchingFilter类的。看一下该类的preHandle()函数实现,可以发现,我们在xml文件中定义的url匹配,在这里面可以看到匹配原则了:

protected boolean preHandle(ServletRequest request, ServletResponse response) throws Exception {
        if (this.appliedPaths == null || this.appliedPaths.isEmpty()) {
            if (log.isTraceEnabled()) {
                log.trace("appliedPaths property is null or empty.  This Filter will passthrough immediately.");
            }
            return true;
        }
        for (String path : this.appliedPaths.keySet()) {
            // If the path does match, then pass on to the subclass implementation for specific checks
            //(first match ‘wins‘):
            if (pathsMatch(path, request)) {
                log.trace("Current requestURI matches pattern ‘{}‘.  Determining filter chain execution...", path);
                Object config = this.appliedPaths.get(path);
                return isFilterChainContinued(request, response, path, config);
            }
        }
        //no path matched, allow the request to go through:
        return true;
    }

继续调用isFilterChainContinued(request, response, path, config)--> onPreHandle(request, response, pathConfig);

分析onPreHandle(),PathMatchingFilter自己并没有实现,只是简单的返回true。所以当我们自定义filter的时候,要将具体的逻辑实现在该方法中,或者实现该类的子类AccessControlFilter(该类对onPreHandle()方法进行了更细致的划分,大部分一般会继承该类)

有兴趣的可以分析一下shiro自带的这些filter

技术分享

 

Shiro的Filter机制详解---源码分析

标签:throw   初始化   st3   img   它的   子类   oid   equal   pattern   

原文地址:http://www.cnblogs.com/ljdblog/p/6237683.html

(0)
(0)
   
举报
评论 一句话评论(0
登录后才能评论!
© 2014 mamicode.com 版权所有  联系我们:gaon5@hotmail.com
迷上了代码!