一、前言
數據庫認證（Database-provided authentication）：應用通過數據庫獲取用戶認證信息。
認證提供者（Authentication Provider）：Spring提供了一系列認證方式，如LDAP、OpenID等，對應的認證服務都需要實現AuthenticationProvider接口，開發人員可以自定義AuthenticationProvider實現。
二、Spring配置
數據庫認證本質上與其它認證方式沒有區別，區別就是獲取用戶及其權限信息的方式不同，數據庫認證需要從數據庫讀取用戶信息，Spring已經預定義了用戶安全的相關表結構和操作實現，請參考下面兩個類的源碼，這些默認實現能滿足大部分應用需求，當然也很容易自己定製。
org.springframework.security.core.userdetails.jdbc.JdbcDaoImpl
org.springframework.security.provisioning.JdbcUserDetailsManager
對於獲取用戶、用戶組、權限的查詢都提供了默認的SQL，所以這也不需要開發者定義，但需要了解Spring的默認實現，如：
public class JdbcDaoImpl extends JdbcDaoSupport implements UserDetailsService {
//~ Static fields/initializers =====================================================================================
public static final String DEF_USERS_BY_USERNAME_QUERY =
"select username,password,enabled " +
"from users " +
"where username = ?";
public static final String DEF_AUTHORITIES_BY_USERNAME_QUERY =
"select username,authority " +
"from authorities " +
"where username = ?";
public static final String DEF_GROUP_AUTHORITIES_BY_USERNAME_QUERY =
"select g.id, g.group_name, ga.authority " +
"from groups g, group_members gm, group_authorities ga " +
"where gm.username = ? " +
"and g.id = ga.group_id " +
"and g.id = gm.group_id";我們可以看到Spring盡一切可能減少開發者的工作，但如果需求不能滿足，開發者需要自定義表結構並覆蓋查詢SQL定義。
public class JdbcUserDetailsManager extends JdbcDaoImpl implements UserDetailsManager, GroupManager {
//~ Static fields/initializers =====================================================================================
// UserDetailsManager SQL
public static final String DEF_CREATE_USER_SQL =
"insert into users (username, password, enabled) values (?,?,?)";
public static final String DEF_DELETE_USER_SQL =
"delete from users where username = ?";
public static final String DEF_UPDATE_USER_SQL =
"update users set password = ?, enabled = ? where username = ?";
public static final String DEF_INSERT_AUTHORITY_SQL =
"insert into authorities (username, authority) values (?,?)";
public static final String DEF_DELETE_USER_AUTHORITIES_SQL =
"delete from authorities where username = ?";
public static final String DEF_USER_EXISTS_SQL =
"select username from users where username = ?";
public static final String DEF_CHANGE_PASSWORD_SQL =
"update users set password = ? where username = ?";
// GroupManager SQL
public static final String DEF_FIND_GROUPS_SQL =
"select group_name from groups";
public static final String DEF_FIND_USERS_IN_GROUP_SQL =
"select username from group_members gm, groups g " +
"where gm.group_id = g.id" +
" and g.group_name = ?";
public static final String DEF_INSERT_GROUP_SQL =
"insert into groups (group_name) values (?)";
public static final String DEF_FIND_GROUP_ID_SQL =
"select id from groups where group_name = ?";
public static final String DEF_INSERT_GROUP_AUTHORITY_SQL =
"insert into group_authorities (group_id, authority) values (?,?)";
public static final String DEF_DELETE_GROUP_SQL =
"delete from groups where id = ?";
public static final String DEF_DELETE_GROUP_AUTHORITIES_SQL =
"delete from group_authorities where group_id = ?";
public static final String DEF_DELETE_GROUP_MEMBERS_SQL =
"delete from group_members where group_id = ?";
public static final String DEF_RENAME_GROUP_SQL =
"update groups set group_name = ? where group_name = ?";
public static final String DEF_INSERT_GROUP_MEMBER_SQL =
"insert into group_members (group_id, username) values (?,?)";
public static final String DEF_DELETE_GROUP_MEMBER_SQL =
"delete from group_members where group_id = ? and username = ?";
public static final String DEF_GROUP_AUTHORITIES_QUERY_SQL =
"select g.id, g.group_name, ga.authority " +
"from groups g, group_authorities ga " +
"where g.group_name = ? " +
"and g.id = ga.group_id ";
public static final String DEF_DELETE_GROUP_AUTHORITY_SQL =
"delete from group_authorities where group_id = ? and authority = ?";數據庫安全認證配置示例：
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:security="http://www.springframework.org/schema/security" xmlns:jdbc="http://www.springframework.org/schema/jdbc" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.2.xsd http://www.springframework.org/schema/security http://www.springframework.org/schema/security/spring-security-3.2.xsd 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"> <context:component-scan base-package="com.stevex.demo" /> <security:http auto-config="true"> <security:intercept-url pattern="/admin" access="ROLE_ADMIN" /> <security:intercept-url pattern="/*" access="ROLE_USER" /> <security:form-login /> </security:http> <security:authentication-manager> <security:authentication-provider> <security:jdbc-user-service data-source-ref="dataSource" group-authorities-by-username-query="select g.id, g.group_name, ga.authority from groups g, group_members gm, group_authorities ga where gm.username = ? and g.id = ga.group_id and g.id = gm.group_id" /> </security:authentication-provider> </security:authentication-manager> <jdbc:embedded-database id="dataSource"> <jdbc:script location="classpath:security-schema.sql" /> <jdbc:script location="classpath:users.sql" /> </jdbc:embedded-database> </beans>
embedded-database標籤：Spring默認使用hsql，如果使用其他內存數據庫，如Derby，需要指定。
jdbc-user-service標籤：注入基於JDBC的UserDetailsService實現，默認即JdbcUserDetailsManager。
group-authorities-by-username-query標籤：覆蓋默認用戶組權限查詢SQL。
authentication-provider標籤：如果沒有設置ref屬性引用其他bean時，默認使用DaoAuthenticationProvider， DaoAuthenticationProvider會調用UserDetailsService接口獲取用戶信息，並在登錄時驗證用戶密碼。
三、後語
本文提供一個基本實現參考供下載。