SpringMVC4零配置--web.xml

http://hanqunfeng.iteye.com/blog/2114967

servlet3.0+规范后，允许servlet，filter，listener不必声明在web.xml中，而是以硬编码的方式存在，实现容器的零配置。

ServletContainerInitializer：启动容器时负责加载相关配置

Java代码  


package javax.servlet;  

import java.util.Set;  

public interface ServletContainerInitializer {  

 public void onStartup(Set<Class<?>> c, ServletContext ctx)  

        throws ServletException;   

}  

 容器启动时会自动扫描当前服务中ServletContainerInitializer的实现类，并调用其onStartup方法，其参数Set<Class<?>> c，可通过在实现类上声明注解javax.servlet.annotation.HandlesTypes(xxx.class)注解自动注入，@HandlesTypes会自动扫描项目中所有的xxx.class的实现类，并将其全部注入Set。

 

Spring为其提供了一个实现类：

SpringServletContainerInitializer

 

Java代码  


package org.springframework.web;  

import java.lang.reflect.Modifier;  

import java.util.LinkedList;  

import java.util.List;  

import java.util.ServiceLoader;  

import java.util.Set;  

import javax.servlet.ServletContainerInitializer;  

import javax.servlet.ServletContext;  

import javax.servlet.ServletException;  

import javax.servlet.annotation.HandlesTypes;  

import org.springframework.core.annotation.AnnotationAwareOrderComparator;  

@HandlesTypes(WebApplicationInitializer.class)  

public class SpringServletContainerInitializer implements ServletContainerInitializer {  

        @Override  

    public void onStartup(Set<Class<?>> webAppInitializerClasses, ServletContext servletContext)  

            throws ServletException {  

  

        List<WebApplicationInitializer> initializers = new LinkedList<WebApplicationInitializer>();  

  

        if (webAppInitializerClasses != null) {  

            for (Class<?> waiClass : webAppInitializerClasses) {  

                // Be defensive: Some servlet containers provide us with invalid classes,  

                // no matter what @HandlesTypes says...  

                if (!waiClass.isInterface() && !Modifier.isAbstract(waiClass.getModifiers()) &&  

                        WebApplicationInitializer.class.isAssignableFrom(waiClass)) {  

                    try {  

                        initializers.add((WebApplicationInitializer) waiClass.newInstance());  

                    }  

                    catch (Throwable ex) {  

                        throw new ServletException("Failed to instantiate WebApplicationInitializer class", ex);  

                    }  

                }  

            }  

        }  

  

        if (initializers.isEmpty()) {  

            servletContext.log("No Spring WebApplicationInitializer types detected on classpath");  

            return;  

        }  

  

        AnnotationAwareOrderComparator.sort(initializers);  

        servletContext.log("Spring WebApplicationInitializers detected on classpath: " + initializers);  

  

        for (WebApplicationInitializer initializer : initializers) {  

            initializer.onStartup(servletContext);  

        }  

    }  

  

}  

 

 从中可以看出，WebApplicationInitializer才是我们需要关心的接口，我们只需要将相应的servlet，filter，listener等硬编码到该接口的实现类中即可。比如：

 

xml配置：

 

Xml代码  


       <!-- Log4jConfigListener -->  

       <context-param>  

    <param-name>log4jConfigLocation</param-name>  

    <param-value>classpath:config/properties/log4j.properties</param-value>  

       </context-param>  

       <listener>  

    <listener-class>org.springframework.web.util.Log4jConfigListener</listener-class>  

       </listener>  

  

       <!-- OpenSessionInViewFilter -->  

       <filter>  

    <filter-name>hibernateFilter</filter-name>  

    <filter-class>  

        org.springframework.orm.hibernate4.support.OpenSessionInViewFilter  

    </filter-class>         

       </filter>  

       <filter-mapping>  

    <filter-name>hibernateFilter</filter-name>  

    <url-pattern>/*</url-pattern>  

       </filter-mapping>  

  

       <!-- DemoServlet -->  

       <servlet>  

    <servlet-name>demoServlet</servlet-name>  

    <servlet-class>web.function.servlet.DemoServlet</servlet-class>  

    <load-on-startup>2</load-on-startup>  

       </servlet>  

<servlet-mapping>  

    <servlet-name>demoServlet</servlet-name>  

    <url-pattern>/demo_servlet</url-pattern>  

</servlet-mapping>  

 编码配置：

 

 

Java代码  


@Order(1)  

public class CommonInitializer implements WebApplicationInitializer{  

  

    @Override  

    public void onStartup(ServletContext servletContext)  

            throws ServletException {  

          

        //Log4jConfigListener  

        servletContext.setInitParameter("log4jConfigLocation", "classpath:config/properties/log4j.properties");  

        servletContext.addListener(Log4jConfigListener.class);  

          

          

        //OpenSessionInViewFilter  

        OpenSessionInViewFilter hibernateSessionInViewFilter = new OpenSessionInViewFilter();  

        FilterRegistration.Dynamic filterRegistration = servletContext.addFilter(  

                "hibernateFilter", hibernateSessionInViewFilter);  

        filterRegistration.addMappingForUrlPatterns(  

                EnumSet.of(DispatcherType.REQUEST, DispatcherType.FORWARD, DispatcherType.INCLUDE), false, "/");  

          

          

        //DemoServlet  

        DemoServlet demoServlet = new DemoServlet();  

        ServletRegistration.Dynamic dynamic = servletContext.addServlet(  

                "demoServlet", demoServlet);  

        dynamic.setLoadOnStartup(2);  

        dynamic.addMapping("/demo_servlet");  

                  

          

    }  

  

      

}  

 

Spring为我们提供了一些WebApplicationInitializer的抽象类，我们只需要继承并按需修改即可，比如：

1）org.springframework.security.web.context.AbstractSecurityWebApplicationInitializer ： SpringSecurity相关配置

 

xml配置：

 

Xml代码  


       <listener>  

    <listener-class>org.springframework.security.web.session.HttpSessionEventPublisher</listener-class>  

</listener>  

  

       <filter>  

    <filter-name>springSecurityFilterChain</filter-name>  

    <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>  

</filter>  

  

       <filter-mapping>  

    <filter-name>springSecurityFilterChain</filter-name>  

    <url-pattern>/*</url-pattern>  

</filter-mapping>  

 

 

编码配置：

 

Java代码  


@Order(2)  

public class WebAppSecurityInitializer  extends AbstractSecurityWebApplicationInitializer   

{  

    //servletContext.addListener("org.springframework.security.web.session.HttpSessionEventPublisher");  

    //session监听器  

    @Override  

    protected boolean enableHttpSessionEventPublisher() {  

        return true;  

    }  

}  

 

2）org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer：MVC相关配置，比如加载spring配置文件，声明DispatcherServlet等等，参看下面的对比：

xml配置：

 

Xml代码  


       <context-param>  

    <param-name>contextConfigLocation</param-name>  

    <param-value>  

    classpath:config/context/applicationContext-AppConfig.xml,  

    classpath:config/context/applicationContext-SpringSecurityConfig.xml  

        </param-value>  

</context-param>  

  

       <listener>  

    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>  

</listener>  

  

       <filter>  

    <filter-name>Set Character Encoding</filter-name>  

    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>  

    <init-param>  

        <param-name>encoding</param-name>  

        <param-value>UTF-8</param-value>  

    </init-param>  

    <init-param>  

        <param-name>forceEncoding</param-name>  

        <param-value>true</param-value>  

    </init-param>  

</filter>  

  

       <filter-mapping>  

    <filter-name>Set Character Encoding</filter-name>  

    <url-pattern>/*</url-pattern>  

</filter-mapping>  

  

       <servlet>  

    <servlet-name>webmvc</servlet-name>  

    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>  

    <init-param>  

        <param-name>contextConfigLocation</param-name>  

        <param-value>classpath:config/context/applicationContext-MvcConfig.xml</param-value>  

    </init-param>  

    <load-on-startup>1</load-on-startup>  

</servlet>  

  

<servlet-mapping>  

    <servlet-name>webmvc</servlet-name>  

    <url-pattern>/</url-pattern>  

</servlet-mapping>  

编码方式：

 

 

Java代码  


@Order(3)  

//spring DispatcherServlet的配置,其它servlet和监听器等需要额外声明，用@Order注解设定启动顺序  

public class WebInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {  

    /* 

      * DispatcherServlet的映射路径 

      */  

    @Override  

    protected String[] getServletMappings() {  

        return new String[]{"/"};  

    }  

   

    /* 

      * 应用上下文，除web部分 

      */  

    @SuppressWarnings({ "unchecked", "rawtypes" })  

    @Override  

    protected Class[] getRootConfigClasses() {  

        //加载配置文件类，这里与上面的xml配置是对应的，需要使用@Configuration注解进行标注，稍后介绍  

        return new Class[] {AppConfig.class, SpringSecurityConfig.class};  

    }  

   

    /* 

      * web上下文 

      */  

    @SuppressWarnings({ "unchecked", "rawtypes" })  

    @Override  

    protected Class[] getServletConfigClasses() {  

        return new Class[] {MvcConfig.class};  

    }  

   

    /* 

      * 注册过滤器，映射路径与DispatcherServlet一致，路径不一致的过滤器需要注册到另外的WebApplicationInitializer中 

      */  

    @Override  

    protected Filter[] getServletFilters() {  

        CharacterEncodingFilter characterEncodingFilter = new CharacterEncodingFilter();  

        characterEncodingFilter.setEncoding("UTF-8");  

        characterEncodingFilter.setForceEncoding(true);  

        return new Filter[] {characterEncodingFilter};  

    }     

  

}  

 

 

 

SpringMVC4零配置 ：代码下载

SpringMVC4零配置--web.xml

SpringMVC4零配置--应用上下文配置【AppConfig】

SpringMVC4零配置--SpringSecurity相关配置【SpringSecurityConfig】

SpringMVC4零配置--Web上下文配置【MvcConfig】