我想问一下spring ioc依赖注入的问题,我写了一个测试用例,单机下没有问题,但在web下就不能注入了

下面分别是测试用例,部分源码,和一些情况

@Test
public void test()
{
    ApplicationContext ctx = new ClassPathXmlApplicationContext("spring-beans.xml");
   UserService userService = (UserService) ctx.getBean("userService");
    System.out.println(userService.findByUsername("Asens"));

    SampleRealm sr=(SampleRealm)ctx.getBean("sampleRealm");
    UserService us=sr.getUserService();
    System.out.println(us.findByUsername("Asens"));
    System.out.println(us);

}

out:

true
true
cn.asens.WebTest.service.impl.UserServiceImpl@5bc11082

这是我写的一个测试,是可以正常运行的
下面是源码

spring-beans.xml

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

       <bean id="userService" class="cn.asens.WebTest.service.impl.UserServiceImpl"></bean>

       <bean id="sampleRealm" class="cn.asens.WebTest.realm.SampleRealm">
              <property name="userService" ref="userService"></property>
       </bean>
</beans>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
version="3.0"
metadata-complete="false">

    <!-- Spring配置文件开始  -->
<context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>
            classpath:spring-beans.xml,
            classpath:spring-shiro-web.xml
        </param-value>
    </context-param>
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    <!-- Spring配置文件结束 -->

    <!-- shiro 安全过滤器 -->
    <!-- The filter-name matches name of a 'shiroFilter' bean inside applicationContext.xml -->
<filter>
        <filter-name>shiroFilter</filter-name>
        <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
        <async-supported>true</async-supported>
        <init-param>
            <param-name>targetFilterLifecycle</param-name>
            <param-value>true</param-value>
        </init-param>
    </filter>

    <!-- Make sure any request you want accessible to Shiro is filtered. /* catches all -->
    <!-- requests.  Usually this filter mapping is defined first (before all others) to -->
    <!-- ensure that Shiro works in subsequent filters in the filter chain:             -->
<filter-mapping>
        <filter-name>shiroFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
</web-app>

UserService

public interface UserService {
    public boolean findByUsername(String username);
}

UserServiceImpl

public class UserServiceImpl implements UserService {
    @Override
public boolean findByUsername(String username) {
        if(username.equals("Asens"))
        {
            return true;
        }
        return false;
    }
}

SampleRealm(有点长就不全贴了)

private UserService userService;

public void setUserService(UserService userService) {
    this.userService = userService;
}

public UserService getUserService() {
    return userService;
}

但是在web中就不能正常注入了

如果把

private UserService userService;

改成

private UserService userService=new UserServiceImpl();

就可以正常运行,说明程序本身的逻辑没问题
test可以正常运行,证明注入问题也不大
但是不明白为什么在web环境下不行