shiro源码篇 - shiro的filter，你值得拥有

前言

　　开心一刻

　　　　已经报废了一年多的电脑，今天特么突然开机了，吓老子一跳，只见电脑管家缓缓地出来了，本次开机一共用时一年零六个月，打败了全国0%的电脑，电脑管家已经对您的电脑失去信心，然后它把自己卸载了，只剩我在一旁发呆。

　　路漫漫其修远兮，吾将上下而求索！

　　github：

　　码云(gitee)：

shirofilter的注册

　　讲到了springboot的filter注册，但只是filter注册的一种方式：通过filterregistrationbean实现。而shiro filter的注册是采用另外的方式实现的，我们接着往下看

　　shirofilterfactorybean实现了factorybean，我们来看下shirofilterfactorybean对factorybean的getobject方法的实现

git图一

　　　　可以看到createinstance()返回的是springshirofilter的实例；springshirofilter的类图如下

　　getobject方法只是创建了一个springshirofilter实例，并注册到了spring容器中，那是如何注册到servlet容器的呢？我们来跟下源码

　　　　其实涉及到了，只是那时候没细讲，我们还是从那里开始

gif图二

　　　　servletcontextinitializerbeans.java的构造方法，里面有addservletcontextinitializerbeans(beanfactory)方法和addadaptablebeans(beanfactory)，我们来好好瞅一瞅

　　　　addservletcontextinitializerbeans(beanfactory)

private void addservletcontextinitializerbeans(listablebeanfactory beanfactory) {
    for (entry<string, servletcontextinitializer> initializerbean : getorderedbeansoftype(
            beanfactory, servletcontextinitializer.class)) {
        addservletcontextinitializerbean(initializerbean.getkey(),
                initializerbean.getvalue(), beanfactory);
    }
}


private void addservletcontextinitializerbean(string beanname,
        servletcontextinitializer initializer, listablebeanfactory beanfactory) {
    if (initializer instanceof servletregistrationbean) {
        servlet source = ((servletregistrationbean<?>) initializer).getservlet();
        addservletcontextinitializerbean(servlet.class, beanname, initializer,
                beanfactory, source);
    }
    else if (initializer instanceof filterregistrationbean) {
        filter source = ((filterregistrationbean<?>) initializer).getfilter();
        addservletcontextinitializerbean(filter.class, beanname, initializer,
                beanfactory, source);
    }
    else if (initializer instanceof delegatingfilterproxyregistrationbean) {
        string source = ((delegatingfilterproxyregistrationbean) initializer)
                .gettargetbeanname();
        addservletcontextinitializerbean(filter.class, beanname, initializer,
                beanfactory, source);
    }
    else if (initializer instanceof servletlistenerregistrationbean) {
        eventlistener source = ((servletlistenerregistrationbean<?>) initializer)
                .getlistener();
        addservletcontextinitializerbean(eventlistener.class, beanname, initializer,
                beanfactory, source);
    }
    else {
        addservletcontextinitializerbean(servletcontextinitializer.class, beanname,
                initializer, beanfactory, initializer);
    }
}

view code

　　　　　　会将spring bean工厂（beanfactory）中类型是servletcontextinitalizer类型的实例（包括servletregistrationbean、filterregistrationbean、delegatingfilterproxyregistrationbean、servletlistenerregistrationbean）添加进servletcontextinitializerbeans的initializers属性中。

private final multivaluemap<class<?>, servletcontextinitializer> initializers;

　　　　　　servletcontextinitalizer的子类图如下所示

　　　　　　这也就是注册filter的方式，以registrationbean方式实现的，但是springshirofilter不是在这添加进servletcontextinitializerbeans的initializers中的哦

　　　　addadaptablebeans(beanfactory)

private void addadaptablebeans(listablebeanfactory beanfactory) {
    multipartconfigelement multipartconfig = getmultipartconfig(beanfactory);
    addasregistrationbean(beanfactory, servlet.class,
            new servletregistrationbeanadapter(multipartconfig));
    addasregistrationbean(beanfactory, filter.class,
            new filterregistrationbeanadapter());
    for (class<?> listenertype : servletlistenerregistrationbean
            .getsupportedtypes()) {
        addasregistrationbean(beanfactory, eventlistener.class,
                (class<eventlistener>) listenertype,
                new servletlistenerregistrationbeanadapter());
    }
}

view code

　　　　　　会将beanfactory中的servlet、filter、listener实例封装成对应的registrationbean，然后添加到servletcontextinitializerbeans的initializers；部分细节没去跟，有兴趣的可以自行去跟下源代码。

　　　　servletcontextinitializerbeans的sortedlist的内容最终如下

　　　　然后遍历这个sortedlist，逐个注入到servlet容器

　　小结

　　　　springboot下有3种方式注册filter（servlet、listener类似），filterregistrationbean、@webfilter 和@bean，@webfilter我还没试过，另外这3种方式注册的filter的优先级是：filterregistrationbean > @webfilter > @bean（网上查阅的资料，我没试哦，使用过程中需要注意！）。

　　　　不管是filterregistrationbean方式、@webfilter方式，还是@bean方式，只要是受spring容器管理，最终都会添加到servletcontextinitializerbeans的initializers中，都会成功注册到servlet容器。@webfilter方式和@bean方式注册的filter都会被封装成filterregistrationbean，然后添加进servletcontextinitializerbeans的initializers；3中方式最终殊途同归，都以filterregistrationbean的形式存在servletcontextinitializerbeans的initializers中。springshirofilter的注册算是@bean方式注册的，至此springshirofilter就注册到了servlet容器中了。

　　　　servletcontextinitializerbeans的sortedlist如下：

private list<servletcontextinitializer> sortedlist;

　　　　是一个有序的servletcontextinitializer list，这个有序针对的同类型，比如所有的filterregistrationbean有序，所有的servletregistrationbean有序，filterregistrationbean与servletregistrationbean之间有没有序是无意义的。

shiro中的filter链

　　shiro的默认filter列表

　　　　除了springshirofilter之外，shiro还有默认的11个filter；细心的朋友应该在git图一中已经发现了，在创建defaultfilterchainmanager，就把默认的11个filter添加到它的filters中

private map<string, filter> filters; //pool of filters available for creating chains

private map<string, namedfilterlist> filterchains; //key: chain name, value: chain

public defaultfilterchainmanager() {
    this.filters = new linkedhashmap<string, filter>();
    this.filterchains = new linkedhashmap<string, namedfilterlist>();
    adddefaultfilters(false);    // 将默认的11个filter添加到filters
}

　　　　这11个filter具体如下

anon(anonymousfilter.class),
authc(formauthenticationfilter.class),
authcbasic(basichttpauthenticationfilter.class),
logout(logoutfilter.class),
nosessioncreation(nosessioncreationfilter.class),
perms(permissionsauthorizationfilter.class),
port(portfilter.class),
rest(httpmethodpermissionfilter.class),
roles(rolesauthorizationfilter.class),
ssl(sslfilter.class),
user(userfilter.class);

　　filter链

　　　　springshirofilter注册到servlet容器中，请求肯定会经过springshirofilter的dofilter方法，我们就从此开始跟一跟源代码

gif图三

　　　　上图中可能展示的不够细，主要就是两点：1、路径匹配：pathmatches(pathpattern, requesturi)，默认的fliter逐个与请求uri进行匹配；2、代理filterchain：proxiedfilterchain。如果匹配不上，那么直接走servlet的filterchain，否则先走shiro的代理filterchain（proxiedfilterchain），之后再走servlet的filterchain。

　　　　proxiedfilterchain源代码如下

/*
 * licensed to the apache software foundation (asf) under one
 * or more contributor license agreements.  see the notice file
 * distributed with this work for additional information
 * regarding copyright ownership.  the asf licenses this file
 * to you 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.apache.shiro.web.servlet;

import org.slf4j.logger;
import org.slf4j.loggerfactory;

import javax.servlet.*;
import java.io.ioexception;
import java.util.list;

/**
 * a proxied filter chain is a {@link filterchain} instance that proxies an original {@link filterchain} as well
 * as a {@link list list} of other {@link filter filter}s that might need to execute prior to the final wrapped
 * original chain.  it allows a list of filters to execute before continuing the original (proxied)
 * {@code filterchain} instance.
 *
 * @since 0.9
 */
public class proxiedfilterchain implements filterchain {

    //todo - complete javadoc

    private static final logger log = loggerfactory.getlogger(proxiedfilterchain.class);

    private filterchain orig;                    // 原filterchain，也就是servlet容器的filterchain
    private list<filter> filters;                // shiro默认的11个filter
    private int index = 0;

    public proxiedfilterchain(filterchain orig, list<filter> filters) {
        if (orig == null) {
            throw new nullpointerexception("original filterchain cannot be null.");
        }
        this.orig = orig;
        this.filters = filters;
        this.index = 0;
    }

    public void dofilter(servletrequest request, servletresponse response) throws ioexception, servletexception {
        if (this.filters == null || this.filters.size() == this.index) {
            //we've reached the end of the wrapped chain, so invoke the original one:
            if (log.istraceenabled()) {
                log.trace("invoking original filter chain.");
            }
            this.orig.dofilter(request, response);                        // 当shiro的11个filter走完之后，继续走servlet容器的filterchain
        } else {
            if (log.istraceenabled()) {
                log.trace("invoking wrapped filter at index [" + this.index + "]");
            }
            this.filters.get(this.index++).dofilter(request, response, this);    // 递归逐个走shiro的11个filter
        }
    }
}

view code

　　　　shiro对servlet容器的filterchain进行了代理，即shirofilter在继续servlet容器的filter链的执行之前，通过proxiedfilterchain对servlet容器的filterchain进行了代理；即先走shiro自己的filter体系，然后才会委托给servlet容器的filterchain进行servlet容器级别的filter链执行；shiro的proxiedfilterchain执行流程：1、先执行shiro自己的filter链；2、再执行servlet容器的filter链（即原始的 filter）。

总结

　　1、springshirofilter注册到spring容器，会被包装成filterregistrationbean，通过filterregistrationbean注册到servlet容器；

　　2、一般而言，shiro的pathmatchingfilterchainresolver会匹配所有的请求，shiro对servlet容器的filterchain进行了代理，生成代理filterchain：proxiedfilterchain，请求先走shiro自己的filter链，再走servelt容器的filter链；

　　3、题外话，springboot注册filter、servlet、listener方式类似，都有3种，具体是哪三种，大家去上文看；关于shiro的filter，本文没做更详细的讲解，需要了解的可以去看《跟我学shiro》

参考

　　《跟我学shiro》

　　shiro源码