Shiro过滤器链

前言

本篇是学习 Shiro 中如何初始化过滤器链的

实践

1. 首先，随便定义几个过滤器

/**
 * @author cuishiying
 * @date 2021-01-22
 */
public class AnonymousFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println("AnonymousFilter init...");
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        System.out.println("AnonymousFilter doFilter...");
        chain.doFilter(request, response);
    }

    @Override
    public void destroy() {
        System.out.println("AnonymousFilter destroy...");
    }
}

/**
 * @author cuishiying
 * @date 2021-01-22
 */
public class FormAuthenticationFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println("AnonymousFilter init...");
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        System.out.println("AnonymousFilter doFilter...");
        chain.doFilter(request, response);
    }

    @Override
    public void destroy() {
        System.out.println("AnonymousFilter destroy...");
    }
}

2. 用枚举将过滤器管理起来

package com.example.demo.shiro;

import org.springframework.objenesis.instantiator.util.ClassUtils;

import javax.servlet.Filter;

/**
 * @author cuishiying
 * @date 2021-01-22
 */
public enum DefaultFilter {

    anon(AnonymousFilter.class),
    authc(FormAuthenticationFilter.class);

    private final Class<? extends Filter> filterClass;

    private DefaultFilter(Class<? extends Filter> filterClass) {
        this.filterClass = filterClass;
    }

    public Filter newInstance() {
        return (Filter) ClassUtils.newInstance(this.filterClass);
    }
}

3. 创建过滤器管理器

package com.example.demo.shiro;

import javax.servlet.Filter;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import java.util.LinkedHashMap;
import java.util.Map;

/**
 * @author cuishiying
 * @date 2021-01-22
 */
public class DefaultFilterChainManager {

    private FilterConfig filterConfig;
    private Map<String, Filter> filters;

    public DefaultFilterChainManager() {
        this.filters = new LinkedHashMap<String, Filter>();
        addDefaultFilters(false);
    }

    public DefaultFilterChainManager(FilterConfig filterConfig) {
        this.filters = new LinkedHashMap<String, Filter>();
        setFilterConfig(filterConfig);
        addDefaultFilters(true);
    }

    private void addDefaultFilters(boolean init) {
        for (DefaultFilter defaultFilter : DefaultFilter.values()) {
            addFilter(defaultFilter.name(), defaultFilter.newInstance(), init, false);
        }
    }

    public Map<String, Filter> getFilters() {
        return filters;
    }

    protected void addFilter(String name, Filter filter, boolean init, boolean overwrite) {
        Filter existing = getFilter(name);
        if (existing == null) {

            if (init) {
                initFilter(filter);
            }
            this.filters.put(name, filter);
        }
    }

    public Filter getFilter(String name) {
        return this.filters.get(name);
    }

    protected void initFilter(Filter filter) {
        FilterConfig filterConfig = getFilterConfig();
        if (filterConfig == null) {
            throw new IllegalStateException("FilterConfig attribute has not been set.  This must occur before filter " +
                    "initialization can occur.");
        }
        try {
            filter.init(filterConfig);
        } catch (ServletException e) {
            throw new RuntimeException(e);
        }
    }

    public FilterConfig getFilterConfig() {
        return filterConfig;
    }

    public void setFilterConfig(FilterConfig filterConfig) {
        this.filterConfig = filterConfig;
    }
}

4. 测试

public class FilterTest {

    public static void main(String[] args) {
        DefaultFilterChainManager defaultFilterChainManager = new DefaultFilterChainManager();
        System.out.println(defaultFilterChainManager.getFilters()); // {anon=com.example.demo.shiro.AnonymousFilter@90f6bfd, authc=com.example.demo.shiro.FormAuthenticationFilter@47f6473}
    }
}

5. spring中集成自定义的 FilterChain

一般我们想在spring中注入过滤器，会通过xml或者代码bean注入。这里我们用xml演示, 代码节选自 shiro

<filter>
    <filter-name>ShiroFilter</filter-name>
    <filter-class>org.apache.shiro.web.servlet.ShiroFilter</filter-class>
</filter>

<filter-mapping>
    <filter-name>ShiroFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

public class ShiroFilter extends AbstractShiroFilter {

    /**
     * Configures this instance based on the existing {@link org.apache.shiro.web.env.WebEnvironment} instance
     * available to the currently accessible {@link #getServletContext() servletContext}.
     *
     * @see org.apache.shiro.web.env.EnvironmentLoaderListener
     * @since 1.2
     */
    @Override
    public void init() throws Exception {
        WebEnvironment env = WebUtils.getRequiredWebEnvironment(getServletContext());

        setSecurityManager(env.getWebSecurityManager());

        FilterChainResolver resolver = env.getFilterChainResolver();
        if (resolver != null) {
            setFilterChainResolver(resolver);
        }
    }
}

public class FilterChainResolver {

    private DefaultFilterChainManager filterChainManager;

    public FilterChainResolver() {
        this.filterChainManager = new DefaultFilterChainManager();
    }

    public FilterChainResolver(FilterConfig filterConfig) {
        this.filterChainManager = new DefaultFilterChainManager(filterConfig);
    }

    public FilterChain getChain(ServletRequest request, ServletResponse response, FilterChain originalChain) {
        DefaultFilterChainManager filterChainManager = getFilterChainManager();
        // 遍历filterChainManager中的过滤器配置, 匹配requestURI与配置的pathPattern, 找出匹配的FilterChain即返回
        return null;
    }

    public DefaultFilterChainManager getFilterChainManager() {
        return filterChainManager;
    }
}

最后

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