是什么原因？

无法找到用于XML模式名称空间的Spring NamespaceHandler [ http://www.springframework.org/schema/security]

org.springframework.web.context.ContextLoader initWebApplicationContext: Context initialization failed
org.springframework.beans.factory.parsing.BeanDefinitionParsingException: Configuration problem: Unable to locate Spring NamespaceHandler for XML schema namespace [http://www.springframework.org/schema/security]
Offending resource: ServletContext resource [/WEB-INF/applicationContext.xml]

这是我的applicationContext.xml：

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/security"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:beans="http://www.springframework.org/schema/beans"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context 
        http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/security
        http://www.springframework.org/schema/security/spring-security-3.0.xsd">
...
</beans:beans>

在我的pom.xml中，我有：

<dependency>
    <groupId>org.springframework.security</groupId>
    <artifactId>spring-security-core</artifactId>      
    <version>3.0.1.RELEASE</version>
</dependency>
<dependency>
    <groupId>org.springframework.security</groupId>
    <artifactId>spring-security-openid</artifactId>
    <version>3.0.1.RELEASE</version>
</dependency>