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对于一个典型的Web应用,完善的认证和授权机制是必不可少的,在SpringFramework中,Juergen Hoeller提供的范例JPetStore给了一些这方面的介绍,但还远远不够,Acegi是一个专门为SpringFramework提供安全机制的 项目,全称为Acegi Security System for Spring,当前版本为0.5.1,就其目前提供的功能,应该可以满足绝大多数应用的需求。

本文的主要目的是希望能够说明如何在基于Spring构架的Web应用中使用Acegi,而不是详细介绍其中的每个接口、每个类。注意,即使对已经存在的Spring应用,通过下面介绍的步骤,也可以马上享受到Acegi提供的认证和授权。

基础工作

在你的Web应用的lib中添加Acegi下载包中的acegi-security.jar

web.xml

实现认证和授权的最常用的方法是通过filter,Acegi亦是如此,通常Acegi需要在web.xml添加以下5个filter:

            

<filter>

<filter-name>Acegi Channel Processing Filter</filter-name>

<filter-class>net.sf.acegisecurity.util.FilterToBeanProxy</filter-class>

<init-param>

<param-name>targetClass</param-name>

<param-value>net.sf.acegisecurity.securechannel.ChannelProcessingFilter</param-value>

</init-param>

</filter>

<filter>

<filter-name>Acegi Authentication Processing Filter</filter-name>

<filter-class>net.sf.acegisecurity.util.FilterToBeanProxy</filter-class>

<init-param>

<param-name>targetClass</param-name>

<param-value>net.sf.acegisecurity.ui.webapp.AuthenticationProcessingFilter</param-value>

</init-param>

</filter>

<filter>

<filter-name>Acegi HTTP BASIC Authorization Filter</filter-name>

<filter-class>net.sf.acegisecurity.util.FilterToBeanProxy</filter-class>

<init-param>

<param-name>targetClass</param-name>

<param-value>net.sf.acegisecurity.ui.basicauth.BasicProcessingFilter</param-value>

</init-param>

</filter>

<filter>

<filter-name>Acegi Security System for Spring Auto Integration Filter</filter-name>

<filter-class>net.sf.acegisecurity.ui.AutoIntegrationFilter</filter-class>

</filter>

<filter>

<filter-name>Acegi HTTP Request Security Filter</filter-name>

<filter-class>net.sf.acegisecurity.util.FilterToBeanProxy</filter-class>

<init-param>

<param-name>targetClass</param-name>

<param-value>net.sf.acegisecurity.intercept.web.SecurityEnforcementFilter</param-value>

</init-param>

</filter>

最先引起迷惑的是net.sf.acegisecurity.util.FilterToBeanProxy,Acegi自己的文档上解释 是:“What  FilterToBeanProxy does is delegate the Filter's methods through to a bean which is obtained from the Spring application context. This enables the bean to benefit from the Spring application context lifecycle support and configuration flexibility.”,如希望深究的话,去看看源代码应该不难理解。

再下来就是添加filter-mapping了:

            

<filter-mapping>

<filter-name>Acegi Channel Processing Filter</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

<filter-mapping>

<filter-name>Acegi Authentication Processing Filter</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

<filter-mapping>

<filter-name>Acegi HTTP BASIC Authorization Filter</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

<filter-mapping>

<filter-name>Acegi Security System for Spring Auto Integration Filter</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

<filter-mapping>

<filter-name>Acegi HTTP Request Security Filter</filter-name>

<url-pattern>/*</url-pattern>

</filter-mapping>

 

这里,需要注意以下三点:

1) 这几个filter的顺序是不能更改的,顺序不对将无法正常工作;

2) 如果你的应用不需要安全传输,如https,则将"Acegi Channel Processing Filter"相关内容注释掉即可;

3) 如果你的应用不需要Spring提供的远程访问机制,如Hessian and Burlap,将"Acegi HTTP BASIC Authorization Filter"相关内容注释掉即可。

 

applicationContext.xml

接下来就是要添加applicationContext.xml中的内容了,从刚才FilterToBeanFactory的解释可以看出,真正的filter都在Spring的applicationContext中管理:

1)首先,你的数据库中必须具有保存用户名和密码的table,Acegi要求table的schema必须如下:

            

CREATE TABLE users (

username VARCHAR(50) NOT NULL PRIMARY KEY,

password VARCHAR(50) NOT NULL,

enabled BIT NOT NULL

);

CREATE TABLE authorities (

username VARCHAR(50) NOT NULL,

authority VARCHAR(50) NOT NULL

);

CREATE UNIQUE INDEX ix_auth_username ON authorities ( username, authority );

ALTER TABLE authorities ADD CONSTRAINT fk_authorities_users foreign key (username)

REFERENCES users

(username);

2)添加访问你的数据库的datasource和Acegi的jdbcDao,如下:

            

<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">

<property name="driverClassName"><value>${jdbc.driverClassName}</value></property>

<property name="url"><value>${jdbc.url}</value></property>

<property name="username"><value>${jdbc.username}</value></property>

<property name="password"><value>${jdbc.password}</value></property>

</bean>

<bean id="jdbcDaoImpl" class="net.sf.acegisecurity.providers.dao.jdbc.JdbcDaoImpl">

<property name="dataSource"><ref bean="dataSource"/></property>

</bean>

3)添加DaoAuthenticationProvider:

            

<bean id="daoAuthenticationProvider"

class="net.sf.acegisecurity.providers.dao.DaoAuthenticationProvider">

<property name="authenticationDao"><ref bean="authenticationDao"/></property>

<property name="userCache"><ref bean="userCache"/></property>

</bean>

<bean id="userCache" class="net.sf.acegisecurity.providers.dao.cache.EhCacheBasedUserCache">

<property name="minutesToIdle"><value>5</value></property>

</bean>

如果你需要对密码加密,则在daoAuthenticationProvider中加入:<property name="passwordEncoder"><ref bean="passwordEncoder"/></property>,Acegi提供了几种加密方法,详细情况可看包 net.sf.acegisecurity.providers.encoding

4)添加authenticationManager:

            

<bean id="authenticationManager" class="net.sf.acegisecurity.providers.ProviderManager">

<property name="providers">

<list>

<ref bean="daoAuthenticationProvider"/>

</list>

</property>

</bean>

5)添加accessDecisionManager:

            

<bean id="accessDecisionManager" class="net.sf.acegisecurity.vote.AffirmativeBased">

<property name="allowIfAllAbstainDecisions">

<value>false</value>

</property>

<property name="decisionVoters">

<list><ref bean="roleVoter"/></list>

</property>

</bean>

<bean id="roleVoter" class="net.sf.acegisecurity.vote.RoleVoter"/>

6)添加authenticationProcessingFilterEntryPoint:

            

<bean id="authenticationProcessingFilterEntryPoint"

class="net.sf.acegisecurity.ui.webapp.AuthenticationProcessingFilterEntryPoint">

<property name="loginFormUrl"><value>/acegilogin.jsp</value></property>

<property name="forceHttps"><value>false</value></property>

</bean>

其中acegilogin.jsp是登陆页面,一个最简单的登录页面如下:

            

<%@ taglib prefix='c' uri='http://java.sun.com/jstl/core' %>

<%@ page import="net.sf.acegisecurity.ui.AbstractProcessingFilter" %>

<%@ page import="net.sf.acegisecurity.AuthenticationException" %>

<html>

<head>

<title>Login</title>

</head>

<body>

<h1>Login</h1>

<form action="<c:url value='j_acegi_security_check'/>" method="POST">

<table>

<tr><td>User:</td><td><input type='text' name='j_username'></td></tr>

<tr><td>Password:</td><td><input type='password' name='j_password'></td></tr>

<tr><td colspan='2'><input name="submit" type="submit"></td></tr>

<tr><td colspan='2'><input name="reset" type="reset"></td></tr>

</table>

</form>

</body>

</html>

7)添加filterInvocationInterceptor:

            

<bean id="filterInvocationInterceptor"

class="net.sf.acegisecurity.intercept.web.FilterSecurityInterceptor">

<property name="authenticationManager">

<ref bean="authenticationManager"/>

</property>

<property name="accessDecisionManager">

<ref bean="accessDecisionManager"/>

</property>

<property name="objectDefinitionSource">

<value>

CONVERT_URL_TO_LOWERCASE_BEFORE_COMPARISON

\A/sec/administrator.*\Z=ROLE_SUPERVISOR

\A/sec/user.*\Z=ROLE_TELLER

</value>

</property>

</bean>

这里请注意,要objectDefinitionSource中定义哪些页面需要权限访问,需要根据自己的应用需求进行修改,我上面给出的定义的意思是这样的:

a. CONVERT_URL_TO_LOWERCASE_BEFORE_COMPARISON意思是在比较请求路径时全部转换为小写

b. \A/sec/administrator.*\Z=ROLE_SUPERVISOR意思是只有权限为ROLE_SUPERVISOR才能访问/sec/administrator*的页面

c. \A/sec/user.*\Z=ROLE_TELLER意思是只有权限为ROLE_TELLER的用户才能访问/sec/user*的页面

8)添加securityEnforcementFilter:

            

<bean id="securityEnforcementFilter"

class="net.sf.acegisecurity.intercept.web.SecurityEnforcementFilter">

<property name="filterSecurityInterceptor">

<ref bean="filterInvocationInterceptor"/>

</property>

<property name="authenticationEntryPoint">

<ref bean="authenticationProcessingFilterEntryPoint"/>

</property>

</bean>

9)添加authenticationProcessingFilter:

            

<bean id="authenticationProcessingFilter"

class="net.sf.acegisecurity.ui.webapp.AuthenticationProcessingFilter">

<property name="authenticationManager">

<ref bean="authenticationManager"/>

</property>

<property name="authenticationFailureUrl">

<value>/loginerror.jsp</value>

</property>

<property name="defaultTargetUrl">

<value>/</value>

</property>

<property name="filterProcessesUrl">

<value>/j_acegi_security_check</value>

</property>

</bean>

其中authenticationFailureUrl是认证失败的页面。

10)如果需要一些页面通过安全通道的话,添加下面的配置:

            

<bean id="channelProcessingFilter"

class="net.sf.acegisecurity.securechannel.ChannelProcessingFilter">

<property name="channelDecisionManager">

<ref bean="channelDecisionManager"/>

</property>

<property name="filterInvocationDefinitionSource">

<value>

CONVERT_URL_TO_LOWERCASE_BEFORE_COMPARISON

\A/sec/administrator.*\Z=REQUIRES_SECURE_CHANNEL

\A/acegilogin.jsp.*\Z=REQUIRES_SECURE_CHANNEL

\A/j_acegi_security_check.*\Z=REQUIRES_SECURE_CHANNEL

\A.*\Z=REQUIRES_INSECURE_CHANNEL

</value>

</property>

</bean>

<bean id="channelDecisionManager"

class="net.sf.acegisecurity.securechannel.ChannelDecisionManagerImpl">

<property name="channelProcessors">

<list>

<ref bean="secureChannelProcessor"/>

<ref bean="insecureChannelProcessor"/>

</list>

</property>

</bean>

<bean id="secureChannelProcessor"

class="net.sf.acegisecurity.securechannel.SecureChannelProcessor"/>

<bean id="insecureChannelProcessor"

class="net.sf.acegisecurity.securechannel.InsecureChannelProcessor"/>

缺少了什么?

Acegi目前提供了两种“secure object”,分别对页面和方法进行安全认证管理,我这里介绍的只是利用FilterSecurityInterceptor对访问页面的权限控制,除 此之外,Acegi还提供了另外一个Interceptor——MethodSecurityInterceptor,它结合runAsManager可 实现对对象中的方法的权限控制,使用方法可参看Acegi自带的文档和contact范例。

最后要说的

本来以为只是说明如何使用Acegi而已,应该非常简单,但真正写起来才发现想要条理清楚的理顺所有需要的bean还是很困难的,但愿我没有遗漏太 多东西,如果我的文章有什么遗漏或错误的话,还请参看Acegi自带的quick-start范例,但请注意,这个范例是不能直接拿来用的。



posted on 2009-06-29 15:09 阅读(2333) 评论(0)  编辑  收藏

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