Spring security中authentication-provider的实现问题

[QuentinYo]

最近在看别人的代码学习Spring，不得不说，Spring涉及的只是太多了，有些找不到头绪。在我正在学习的代码中用到了Spring security，它的配置文件如下：

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/security"
	xmlns:beans="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-3.1.xsd
        http://www.springframework.org/schema/security http://www.springframework.org/schema/security/spring-security-3.1.xsd">
	
	<!-- HTTP security configurations -->
	<http auto-config="true" use-expressions="true">
		<!-- <form-login login-processing-url="/resources/j_spring_security_check" login-page="/login" authentication-failure-url="/login?login_error=t" /> -->
		<form-login login-page="/login" authentication-failure-url="/login?error=true" default-target-url="/" />
		<logout logout-url="/j_spring_security_logout" />
		<intercept-url pattern="/login" access="permitAll" />
		<intercept-url pattern="/**/rest/**" access="permitAll" />
		<intercept-url pattern="/resources/**" access="permitAll" />
		<intercept-url pattern="/**" access="isAuthenticated()" />
		<intercept-url pattern="/sessionTimeout.html" access="permitAll" />
	</http>
	
	<!-- Configure Authentication mechanism -->
	<authentication-manager alias="authenticationManager">
		<authentication-provider ref="provider"></authentication-provider>
	</authentication-manager>
</beans:beans>

它的authentication-provider指定了一个实现类是provider，但是我找遍所有的配置文件都没发现一个叫provider的bean，只在jpa的持久化配置文件中发现一个<provider>标签，请问大家authentication-provider是怎么实现的
（不知道给出的信息够不够，能不能让大家做出判断）

jpa持久化配置文件：

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.0"
	xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
	<persistence-unit name="persistenceUnit" transaction-type="RESOURCE_LOCAL">
		<provider>org.hibernate.ejb.HibernatePersistence</provider>
		<properties>
			<property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5InnoDBDialect" />
			<!-- value="create" to build a new database on each run; value="update" 
				to modify an existing database; value="create-drop" means the same as "create" 
				but also drops tables when Hibernate closes; value="validate" makes no changes 
				to the database -->
			<property name="hibernate.hbm2ddl.auto" value="validate" />
			<property name="hibernate.ejb.naming_strategy" value="org.hibernate.cfg.DefaultNamingStrategy" />
			<property name="hibernate.connection.charSet" value="UTF-8" />
			<!-- Uncomment the following two properties for JBoss only -->
			<!-- property name="hibernate.validator.apply_to_ddl" value="false" / -->
			<!-- property name="hibernate.validator.autoregister_listeners" value="false" 
				/ -->
		</properties>
	</persistence-unit>
</persistence>

[zuxianghuang]

在jpa的持久化配置文件中发现一个<provider>标签，这个和security里的不是一回事， 没有关联的， <authentication-provider ref="provider"></authentication-provider> provider 这个对象肯定是配置了的，如果没有，是会报错的

[QuentinYo]

provider 是在代码中用注解配置的，找了很久才看到