Cxf——动态加载

我们的目标是在测试环境下非Cxf开发时启动不进行Cxf环境的加载, 正式环境或Cxf开发时启动即进行Cxf环境的装载.

1. 概述

1. 主要是利用了servlet3.0规范里新增的ServletContainerInitializer接口.
2. 当然我们不会直接使用该接口, 而是退而求次地借助于spring-web中的SpringServletContainerInitializer中声明的WebApplicationInitializer接口.

2. 代码

// 居于 AbstractHttpSessionApplicationInitializer执行时机之后@Order(101)public class CxfInitializer implements WebApplicationInitializer {    // 动态加载Cxf, 加快测试环境下启动速度    @Override    public void onStartup(ServletContext servletContext) throws ServletException {        String startImmediately = (String) PropertiesUtil.getProperty("cxf.startImmediately");        if (!("true".equalsIgnoreCase(startImmediately))) {            return;        }        injectContextParam(servletContext);        registerServlet(servletContext);    }    @SuppressWarnings("unchecked")    private void injectContextParam(ServletContext servletContext) {        // ContextLoaderListener的执行时机比这个方法执行的时机要晚, 所以我们在这里将spring-cxf-service.xml配置文件加入<context-param>是来得及的        // 不过这里有个细节就是在Tomcat对servletContext.setInitParameter的实现中使用的是ConcurrentMap<String, String>.putIfAbsent来完成的. 所以我们必须采取先移除, 在插入的操作.        // 感觉最近的几个需求都得剑走偏锋.        /*            <context-param>                <param-name>contextConfigLocation</param-name>                <param-value>                    classpath:config/spring.xml;                    <!-- cxf配置 -->                    classpath:config/spring-cxf-service.xml;                </param-value>            </context-param>        */        String contextConfigLocationInitParameter = StringUtils.EMPTY;        // 所以以下是依赖于Servlet容器的        ConcurrentMap<String, String> parameters = (ConcurrentMap<String, String>) SystemMetaObject                .forObject(servletContext).getValue("context.parameters");        // 确保插入 spring-cxf-service.xml 配置文件        if (parameters.containsKey("contextConfigLocation")) {            contextConfigLocationInitParameter = servletContext.getInitParameter("contextConfigLocation");            if (!contextConfigLocationInitParameter.contains("spring-cxf-service.xml")) {                contextConfigLocationInitParameter += "classpath:config/spring-cxf-service.xml;";            }            parameters.remove("contextConfigLocation");        }else{            contextConfigLocationInitParameter += "classpath:config/spring-cxf-service.xml;";        }        servletContext.setInitParameter("contextConfigLocation", contextConfigLocationInitParameter);    }    private void registerServlet(ServletContext servletContext) {        /*            <!-- cxf servlet -->            <servlet>                <servlet-name>CXFServlet</servlet-name>                <servlet-class>                    org.apache.cxf.transport.servlet.CXFServlet                </servlet-class>                <load-on-startup>1</load-on-startup>            </servlet>            <servlet-mapping>                <servlet-name>CXFServlet</servlet-name>                <url-pattern>/webservice/*</url-pattern>            </servlet-mapping>          */        javax.servlet.ServletRegistration.Dynamic registration = servletContext.addServlet(                "CXFServlet", org.apache.cxf.transport.servlet.CXFServlet.class);        registration.setLoadOnStartup(1);        registration.addMapping("/webservice/*");    }}

3. 关键思路

1. <context-param /> , Listener, ServletContainerInitializer的生效时机的先后顺序.
2. Tomcat容器对添加<context-param />的处理逻辑.