spring web，security+web.xml+mvc dispatcher+Bean创建了两次 报错 拼音 双语对照

Question

我有如下的Web.xml：

 <servlet>
    <servlet-name>mvc-dispatcher</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
    <servlet-name>mvc-dispatcher</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>
<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>/api/secure/*</url-pattern>
</filter-mapping>

[编辑]

添加spring security后，我得到了错误！

java.lang.IllegalStateException：找不到WebApplicationContext：没有注册ContextLoaderListener吗？

然后我加了

 <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>
            /WEB-INF/mvc-dispatcher-servlet.xml
        </param-value>
    </context-param>
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

那么似乎工作正常，但是然后1）问题是bean被创建了两次！

如果我只删除它：

<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>
        /WEB-INF/mvc-dispatcher-servlet.xml
    </param-value>
</context-param>

但离开该 Web应用程序则根本无法运行

[额外]

完整的Web.xml如下：

<web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

    <display-name>Spring MVC Application</display-name>

    <servlet>
        <servlet-name>mvc-dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>mvc-dispatcher</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

    <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>/api/secure/*</url-pattern>
    </filter-mapping>

    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>
            /WEB-INF/mvc-dispatcher-servlet.xml
        </param-value>
    </context-param>

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

</web-app>

这是我的mvc-dispatcher-servlet.xml

<beans xmlns="http://www.springframework.org/schema/beans" 
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:jpa="http://www.springframework.org/schema/data/jpa"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:security="http://www.springframework.org/schema/security"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
                            http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
                            http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
                            http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa.xsd
                            http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
                            http://www.springframework.org/schema/security http://www.springframework.org/schema/security/spring-security-3.1.xsd">

    <mvc:annotation-driven/>
    <context:annotation-config/>
    <context:component-scan base-package="com.ge.wtracker"/>
    <context:property-placeholder location="classpath*:META-INF/spring/*.properties"/>

    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/pages/"/>
        <property name="suffix" value=".jsp"/>
    </bean>

    <!--Java Persistence API config-->
    <jpa:repositories base-package="com.ge.wtracker.repository"/>

    <!--JPA and Database Config-->
    <tx:annotation-driven transaction-manager="transactionManager"/>
    <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="persistenceUnitName" value="defaultPersistenceUnit"/>
        <property name="dataSource" ref="dataSource"/>
    </bean>
    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="entityManagerFactory" />
    </bean>
    <bean class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close" id="dataSource">
        <property name="driverClassName" value="${database.driverClassName}"/>
        <property name="url" value="${database.url}"/>
        <property name="username" value="${database.username}"/>
        <property name="password" value="${database.password}"/>
        <property name="testOnBorrow" value="true"/>
        <property name="testOnReturn" value="true"/>
        <property name="testWhileIdle" value="true"/>
        <property name="timeBetweenEvictionRunsMillis" value="1800000"/>
        <property name="numTestsPerEvictionRun" value="3"/>
        <property name="minEvictableIdleTimeMillis" value="1800000"/>
        <property name="validationQuery" value="SELECT 1"/>
    </bean>

    <!--Spring Security-->
    <security:http create-session="stateless" entry-point-ref="restAuthenticationEntryPoint" authentication-manager-ref="authenticationManager">
        <security:intercept-url pattern="/api/secure/**" access="ROLE_USER" />
        <security:custom-filter ref="customRestFilter" position="BASIC_AUTH_FILTER" />
    </security:http>
    <!-- Configures the authentication entry point that returns HTTP status code 401 -->
    <bean id="restAuthenticationEntryPoint" class="com.ge.wtracker.web.security.RestAuthenticationEntryPoint">
        <property name="realmName" value="Not Authorized" />
    </bean>
    <security:authentication-manager alias="authenticationManager">
        <security:authentication-provider ref="restAuthenticationProvider" />
    </security:authentication-manager>

    <!--The customRestFilter responsibles for retrieving and manipulating any request data to pass to the authentication
        provider to authenticate.-->
    <bean id="customRestFilter" class="com.ge.wtracker.web.security.RestSecurityFilter">
        <constructor-arg name="authenticationManager" ref="authenticationManager" />
        <constructor-arg name="authenticationEntryPoint" ref="restAuthenticationEntryPoint" />
    </bean>
    <bean id="restAuthenticationProvider" class="com.ge.wtracker.web.security.RestAuthenticationProvider" />

</beans>

Answer 1

在Servlet容器生命周期内，容器首先初始化ServletContextListener，然后初始化Filter和Servlet实例。

Spring Web应用程序通常加载两个上下文：根上下文和调度程序servlet上下文。的ContextLoaderListener类是ServletContextListener它加载应用程序（或根）上下文。它通过context-param使用contextConfigLocation像下面的web.xml中给出的名称标识要加载的文件

<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>
        /WEB-INF/mvc-dispatcher-servlet.xml
    </param-value>
</context-param>

或者，默认情况下，通过在上查找文件/WEB-INF/applicationContext.xml。由于你已指定/WEB-INF/mvc-dispatcher-servlet.xml为contextConfigLocation，因此将加载该上下文。

完成此操作后，容器将初始化DispatcherServlet，同时还会加载上下文。它通过具有以下web.xml中给定init-param名称的元素来标识文件加载contextConfigLocation

<servlet>
    <servlet-name>dispatcher</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/spring/appServlet/some-random-location.xml</param-value>
    </init-param>
</servlet>

或者，默认情况下，通过在上查找文件/WEB-INF/name-of-your-servlet-servlet.xml。换句话说，它获取<servlet-name>元素的值并将-servlet.xml其追加并在中查找WEB-INF。

由于你未指定init-paramwith的名称contextConfigLocation，因此DispatcherServlet将上下文文件加载到/WEB-INF/mvc-dispatcher-servlet.xml，因为其名称为mvc-dispatcher。由加载的上下文DispatcherServlet可以访问由加载的Bean ContextLoaderListener，因此我们将其称为根上下文（以及其他子代）。

所有这一切都说明你ContextLoaderListener和你DispatcherServlet正在ApplicationContext通过分别XmlWebApplicationContext从加载相同文件来创建自己的副本/WEB-INF/mvc-dispatcher-servlet.xml。

确定你认为整个应用程序可以使用哪些bean或配置，并将它们放在将由加载的文件中ContextLoaderListener。确定你认为应该可用的bean或配置DispatcherServlet，并将其放入其上下文文件中。