一、前言
数据库认证（Database-provided authentication）：应用通过数据库获取用户认证信息。
认证提供者（Authentication Provider）：Spring提供了一系列认证方式，如LDAP、OpenID等，对应的认证服务都需要实现AuthenticationProvider接口，开发人员可以自定义AuthenticationProvider实现。
二、Spring配置
数据库认证本质上与其它认证方式没有区别，区别就是获取用户及其权限信息的方式不同，数据库认证需要从数据库读取用户信息，Spring已经预定义了用户安全的相关表结构和操作实现，请参考下面两个类的源码，这些默认实现能满足大部分应用需求，当然也很容易自己定制。
org.springframework.security.core.userdetails.jdbc.JdbcDaoImpl
org.springframework.security.provisioning.JdbcUserDetailsManager
对于获取用户、用户组、权限的查询都提供了默认的SQL，所以这也不需要开发者定义，但需要了解Spring的默认实现，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";
我们可以看到Spring尽一切可能减少开发者的工作，但如果需求不能满足，开发者需要自定义表结构并覆盖查询SQL定义。
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 = ?";
数据库安全认证配置示例：
<?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标签：Spring默认使用hsql，如果使用其他内存数据库，如Derby，需要指定。
jdbc-user-service标签：注入基于JDBC的UserDetailsService实现，默认即JdbcUserDetailsManager。
group-authorities-by-username-query标签：覆盖默认用户组权限查询SQL。
authentication-provider标签：如果没有设置ref属性引用其他bean时，默认使用DaoAuthenticationProvider， DaoAuthenticationProvider会调用UserDetailsService接口获取用户信息，并在登录时验证用户密码。
三、后语
本文提供一个基本实现参考供下载。
本文出自 “力量来源于赤诚的爱！” 博客，请务必保留此出处http://stevex.blog.51cto.com/4300375/1363802