Servlet3.0动态配置过滤器、监听器、Servlet

Servlet 3.0 作为 Java EE 6 规范体系中一员，随着 Java EE 6 规范一起发布。该版本在前一版本（Servlet 2.5）的基础上提供了若干新特性用于简化 Web 应用的开发和部署。然后本博客就其中的一个特征，动态配置过滤器、监听器、Servlet，进行介绍

<dependency>
	<groupId>javax.servlet</groupId>
	<artifactId>javax.servlet-api</artifactId>
	<scope>provided</scope>
	<version>3.1.0</version>
</dependency>

实现AbstractAnnotationConfigDispatcherServletInitializer类：

package com.extra.login.core.servlet;

import com.extra.login.cas.client.filter.authentication.AuthenticationFilter;
import com.extra.login.cas.client.filter.session.SingleSignOutFilter;
import com.extra.login.cas.client.util.AssertionThreadLocalFilter;
import com.extra.login.cas.client.util.CasParamKeyEnum;
import com.extra.login.cas.client.util.CasPropertiesLoader;
import com.extra.login.cas.client.util.HttpServletRequestWrapperFilter;
import org.jasig.cas.client.session.SingleSignOutHttpSessionListener;
import org.jasig.cas.client.validation.Cas30ProxyReceivingTicketValidationFilter;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

import javax.servlet.*;
import java.util.EnumSet;


/**
 * <pre>
 *      基于Servlet3.0实现动态配置过滤器、监听器、Servlet
 * </pre>
 *
 * <pre>
 * @author mazq
 * 修改记录
 *    修改后版本:     修改人：  修改日期: 2020/08/27 14:33  修改内容:
 * </pre>
 */
@Component
public class WebServletInitializer extends AbstractAnnotationConfigDispatcherServletInitializer  {


    @Override
    protected Class<?>[] getRootConfigClasses() {
        return new Class[0];
    }

    @Override
    protected Class<?>[] getServletConfigClasses() {
        return new Class[0];
    }

    @Override
    protected String[] getServletMappings() {
        return new String[0];
    }

    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        this.registerCasFilter(servletContext);
        this.registerCasListener(servletContext);
        super.onStartup(servletContext);
    }

    /**
     *  动态注册CAS过滤器
     * @Author mazq
     * @Date 2020/08/27 16:41
     * @Param [servletContext]
     * @return void
     */
    protected void registerCasFilter(ServletContext servletContext) {
        /* CAS单点登录校验过滤器 */
        FilterRegistration casFilter = servletContext.addFilter("casFilter", AuthenticationFilter.class);
        casFilter.setInitParameter("casServerLoginUrl" , CasPropertiesLoader.getValue(CasParamKeyEnum.CAS_SERVER_HOST_LOGIN_URL.getCasParamKey()));
        casFilter.setInitParameter("serverName" , CasPropertiesLoader.getValue(CasParamKeyEnum.APP_SERVER_HOST_URL.getCasParamKey()));
        casFilter.setInitParameter("ignorePattern" , "/static/*");
        casFilter.addMappingForUrlPatterns(EnumSet.allOf(DispatcherType.class) , true, "/*");
        /* CAS单点登录ticket校验过滤器 */
        FilterRegistration casValidationFilter = servletContext.addFilter("casValidationFilter", Cas30ProxyReceivingTicketValidationFilter.class);
        casValidationFilter.setInitParameter("casServerUrlPrefix" , CasPropertiesLoader.getValue(CasParamKeyEnum.CAS_SERVER_HOST_URL.getCasParamKey()));
        casValidationFilter.setInitParameter("serverName" , CasPropertiesLoader.getValue(CasParamKeyEnum.APP_SERVER_HOST_URL.getCasParamKey()));
        casValidationFilter.setInitParameter("redirectAfterValidation" , "true");
        casValidationFilter.setInitParameter("useSession" , "true");
        casValidationFilter.setInitParameter("encoding" , "UTF-8");
        casValidationFilter.addMappingForUrlPatterns(EnumSet.allOf(DispatcherType.class) , true, "/*");
        /* CAS单点登出过滤器 */
        FilterRegistration singleSignOutFilter = servletContext.addFilter("singleSignOutFilter", SingleSignOutFilter.class);
        singleSignOutFilter.setInitParameter("casServerUrlPrefix" , CasPropertiesLoader.getValue(CasParamKeyEnum.CAS_SERVER_HOST_URL.getCasParamKey()));
        singleSignOutFilter.addMappingForUrlPatterns(EnumSet.allOf(DispatcherType.class) , true, "/*");
        /* HttpServletRequestWrapper过滤器 */
        FilterRegistration httpServletRequestWrapperFilter = servletContext.addFilter("httpServletRequestWrapperFilter", HttpServletRequestWrapperFilter.class);
        httpServletRequestWrapperFilter.addMappingForUrlPatterns(EnumSet.allOf(DispatcherType.class) , true, "/*");
        /* AssertionThreadLocal过滤器 */
        FilterRegistration assertionThreadLocalFilter = servletContext.addFilter("assertionThreadLocalFilter", AssertionThreadLocalFilter.class);
        assertionThreadLocalFilter.addMappingForUrlPatterns(EnumSet.allOf(DispatcherType.class) , true, "/*");
    }

    /**
     * 注册CAS监听器
     * @Author mazq
     * @Date 2020/08/27 16:43
     * @Param [servletContext]
     * @return void
     */
    protected void registerCasListener(ServletContext servletContext){
        //注册监听器
        servletContext.addListener(SingleSignOutHttpSessionListener.class);
    }

    @Override
    protected FilterRegistration.Dynamic registerServletFilter(ServletContext servletContext, Filter filter) {
        return super.registerServletFilter(servletContext, filter);
    }

    @Override
    protected void registerContextLoaderListener(ServletContext servletContext) {
        super.registerContextLoaderListener(servletContext);
    }
}