Spring Security调研记录【七】--核心模型与实现

网上有很多关于Spring Security文章中，都认为Spring Security（相对于shiro）过于复杂，个人认为复杂的是Spring Security的官方文档而不是Spring Security本身。

Spring Security满足了用户认证与授权的几乎所有应用场景，在其核心模型下，扩展随心所欲！

一、认证与权限过程模型及Spring Security的处理过程

我们普遍的认证与授权过程如下图所示。



①是否已登录？：

在Spring Security中，接口AuthenticationTrustResolver有一个方法isAnonymous(Authentication)，用于判断当前用户是否为匿名用户（匿名用户则为未登录用户）。

AuthenticationTrustResolver接口的实现类由ExceptionTranslationFilter过滤器调用。

ExceptionTranslationFilter在处理AccessDeniedException异常时，如果当前用户为匿名则调用“②登录入口”；否则调用“⑤无权访问处理”。

②登录入口：

Spring Security中，登录入口由接口AuthenticationEntryPoint提供，如果你不想提供一个登录界面，而是通过json返回一个特定字符串，指示客户端提供登录入口，只要提供一个的AuthenticationEntryPoint实现类组装到Spring
Security的上下文即可，在第三部分会一个具体实现。

AuthenticationEntryPoint由ExceptionTranslationFilter调用，默认实现是提供一个登录页面。

③登录认证是否通过？：

Spring Security中，登录认证由过滤器UsernamePasswordAuthenticationFilter（AbstractAuthenticationProcessingFilter）提供。过滤器通过判断当前Url是否为/login（可配置），是则处理。

AbstractAuthenticationProcessingFilter委托AuthenticationManager进行用户登录认证，成功则调用AuthenticationSuccessHandler进行处理，否则调用AuthenticationFailureHandler进行处理。

AuthenticationSuccessHandler默认处理是只记录Session，结束当前过滤器处理，进行下一个过滤器处理。

AuthenticationFailureHandler默认处理是抛出AuthenticationException异常，由后面的ExceptionTranslationFilter统一处理。ExceptionTranslationFilter对于AuthenticationException异常，会调用AuthenticationEntryPoint进行处理。

如果希望登录成功或失败通过Json返回客户端，就可以重实现接口AuthenticationSuccessHandler和AuthenticationFailureHandler，组装到Spring
Security的上下文。

具体情况请见第二部分。

④是否有权访问？：

Spring Security中，是否有权访问资源的检查是在FilterSecurityInterceptor过滤器中，FilterSecurityInterceptor委托AccessDecisionManager进行权限检查。

具体情况请见第二部分。

⑤无权访问处理：

如果无权访问，则抛出AccessDeniedException异常。AccessDeniedException由ExceptionTranslationFilter统一处理，ExceptionTranslationFilter会委托接口AccessDeniedHandler进行处理。

AccessDeniedHandler的默认实现会抛出403错误。如希望在无权访问某资源时，返回json信息而不是403错误，可通过重实现AccessDeniedHandler，并组装到Spring Security上下文中即可。

二、核心模型

核心模型总结为如下三张图，Filter、Authentication、Access

1、过滤器模式

Spring Security整体是通过管道（过滤器）模式实现功能。过滤器以如下顺序执行：



1）ChannelProcessingFilter

官方解释：“because it might
need to redirect to a different protocol”

未明，暂且不理。

2）SecurityContextPersistenceFilter

本过滤器作用为从Session中加载SecurityContext (可获得Authentication)，保存到SecurityContextHolder中，在处理完成后，把SecurityContextHolder中的SecurityContext
保存到session中。

如果要实现session集中化存储或缓存，则需要修改本过滤器。

3）ConcurrentSessionFilter

4）AbstractAuthenticationProcessingFilter

5）SecurityContextHolderAwareRequestFilter

6）JaasApiIntegrationFilter

7）RememberMeAuthenticationFilter

8）AnonymousAuthenticationFilter

9）ExceptionTranslationFilter

10）FilterSecurityInterceptor

2、登录模型



1）AbstractAuthenticationProcessingFilter

AbstractAuthenticationProcessingFilter只对特定的Url进行处理，如：/login（可配置），通过把userName和password信息封装到Authentication中，委托AuthenticationManager进行认证。如果认证成功则调用AuthenticationSuccessHandler进行处理，否则调用AuthenticationFailureHandler进行处理。

2）AuthenticationManager

AuthenticationManager里配置了一个AuthenticationProvider列表，循环调用其中的AuthenticationProvider进行认证，如果有一个认证成功则返回，如果所以AuthenticationProvider都认证失败则认为失败。

3）AuthenticationProvider

AuthenticationProvider默认实现，通过UserDetailsService加载UserDetails，对UserDetails与Authentication的credentials进行比较。

4）UserDetailsService

本接口只有一个方法：UserDetails loadUserByUsername(String username) throws UsernameNotFoundException;
如需要通过Spring Security与已有的用户管理系统对接，只要重实现该接口即可。

3、权限检测与异常转换处理模型



1）ExceptionTranslationFilter

Spring Security 在认证与权限检查过程中，都不立刻进行处理，而都是抛出相应的异常，由ExceptionTranslationFilter对不同异常调用不同接口进行处理。

AccessDeniedExceiption异常，对于非匿名用户，由AccessDeniedHandler进行处理，否则由AuthenticationEntryPoint进行处理。

AuthenticationException异常，则由AuthenticationEntryPoint进行处理。

AuthenticationTrustResolver接口用于判断当前用户是否为匿名用户。

2）FilterSecurityInterceptor

FilterSecurityInterceptor主要进行权限检查工作，如果需要再次认证，则也调用AuthenticationManager进行认证，但一般不用再次认证。

FilterSecurityInterceptor，通过FilterInvocationSecurityMetadataSource，获取当前Url资源需要的角色信息ConfigAttribute；同时把该ConfigAttribute和当前用户的Authentication，传递予AccessDecisionManager进行权限检查。

如果希望Url资源的角色要求可通过第三方系统获取，只要重实现FilterInvocationSecurityMetadataSource接口即可。

三、实例

实现通过username从第三方系统获取用户信息UserDetails（用户名、密码、是否超期、是否被锁、用户角色列表）

实现同第三方获取Url资源所需要的角色列表。

1、web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee" xmlns:jsp="http://java.sun.com/xml/ns/javaee/jsp"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>SpringSecurityTest</display-name>

<filter>
<filter-name>encodingFilter</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>UTF-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>encodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/spring-context.xml</param-value>
</context-param>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>

<filter>
<filter-name>springSecurityFilterChain</filter-name>
<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
</filter>

<filter-mapping>
<filter-name>springSecurityFilterChain</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>

<servlet>
<servlet-name>springmvc</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>

<servlet-mapping>
<servlet-name>springmvc</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>

<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<error-page>
<error-code>500</error-code>
<location>/errorpage.jsp</location>
</error-page>
<error-page>
<error-code>400</error-code>
<location>/errorpage.jsp</location>
</error-page>
<error-page>
<error-code>404</error-code>
<location>/errorpage.jsp</location>
</error-page>
</web-app>

2、spring-security-context.xml配置

<?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-3.0.xsd http://www.springframework.org/schema/security http://www.springframework.org/schema/security/spring-security.xsd"> <http pattern="/**/*.css" security="none" />
<http pattern="/**/*.js" security="none" />

<http pattern="/security/**" access-decision-manager-ref="accessDecisionManager" once-per-request="false">
<form-login login-page="/security/login"
login-processing-url="/security/loginprocess" default-target-url="/security/index"
always-use-default-target="false" authentication-failure-url="/security/login?error=wrong_login_data"
username-parameter="username" password-parameter="password" />
<logout logout-url="/security/logout" />
<intercept-url pattern="/security/login" access="permitAll()" />
<intercept-url pattern="/security/logout" access="permitAll()" />
<intercept-url pattern="/security/**" access="hasRole('NORMALUSER')" />
<custom-filter ref="winssageFilterSecurityInterceptor"
before="FILTER_SECURITY_INTERCEPTOR" />
<csrf disabled="true" />
</http>

<global-method-security pre-post-annotations="enabled" />

<beans:bean name="bcryptEncoder"
class="org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder" />

<authentication-manager alias="authenticationManager">
<authentication-provider user-service-ref='myUserDetailsService'>
<password-encoder ref="bcryptEncoder" />
</authentication-provider>
</authentication-manager>

<beans:bean id="myUserDetailsService"
class="com.winssage.spring.security.userdetails.WinssageUserDetailsService">
<beans:property name="bcryptPasswordEncoder" ref="bcryptEncoder" />
</beans:bean>

<beans:bean id="winssageFilterSecurityInterceptor"
class="org.springframework.security.web.access.intercept.FilterSecurityInterceptor">
<beans:property name="authenticationManager" ref="authenticationManager" />
<beans:property name="accessDecisionManager" ref="accessDecisionManager" />
<beans:property name="securityMetadataSource" ref="securityMetadataSource" />
</beans:bean>

<beans:bean id="accessDecisionManager"
class="org.springframework.security.access.vote.AffirmativeBased">
<beans:constructor-arg name="decisionVoters">
<beans:list>
<beans:bean class="org.springframework.security.access.vote.RoleVoter">
<beans:property name="rolePrefix" value="ROLE_" />
</beans:bean>
<beans:bean
class="org.springframework.security.access.vote.AuthenticatedVoter" />
<beans:bean
class="org.springframework.security.web.access.expression.WebExpressionVoter" />
</beans:list>
</beans:constructor-arg>
</beans:bean>

<beans:bean id="securityMetadataSource"
class="com.winssage.spring.security.access.intercept.WinssageSecurityMetadataSource">
<beans:constructor-arg ref="securityMetadataSourceAdapter" />
</beans:bean>

<beans:bean id="securityMetadataSourceAdapter"
class="com.winssage.spring.security.DefaultSecurityMetadataSourceAdapter">
</beans:bean>
</beans:beans>

3、WinssageUserDetailsService

package com.winssage.spring.security.userdetails;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import javax.annotation.Resource;

import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.security.core.userdetails.User;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.core.userdetails.UsernameNotFoundException;
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;

public class WinssageUserDetailsService implements UserDetailsService {

BCryptPasswordEncoder bcryptPasswordEncoder;

@Override
public UserDetails loadUserByUsername(String username)
throws UsernameNotFoundException {

List<GrantedAuthority> grantedAuths = new ArrayList<GrantedAuthority>();
grantedAuths.add(new SimpleGrantedAuthority("ROLE_USER"));
grantedAuths.add(new SimpleGrantedAuthority("ROLE_NORMALUSER"));

boolean enables = true;
boolean accountNonExpired = true;
boolean credentialsNonExpired = true;
boolean accountNonLocked = true;
String password=(null==bcryptPasswordEncoder)?"123456":bcryptPasswordEncoder.encode("123456");
User userdetail = new User(username, password, enables,
accountNonExpired, credentialsNonExpired, accountNonLocked,
grantedAuths);
return userdetail;
}

public BCryptPasswordEncoder getBcryptPasswordEncoder() {
return bcryptPasswordEncoder;
}

public void setBcryptPasswordEncoder(BCryptPasswordEncoder bcryptPasswordEncoder) {
this.bcryptPasswordEncoder = bcryptPasswordEncoder;
}

}

4、WinssageSecurityMetadataSource

package com.winssage.spring.security.access.intercept;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.expression.ExpressionParser;
import org.springframework.expression.ParseException;
import org.springframework.security.access.ConfigAttribute;
import org.springframework.security.access.SecurityConfig;
import org.springframework.security.access.expression.SecurityExpressionHandler;
import org.springframework.security.web.FilterInvocation;
import org.springframework.security.web.access.intercept.DefaultFilterInvocationSecurityMetadataSource;
import org.springframework.security.web.access.intercept.FilterInvocationSecurityMetadataSource;
import org.springframework.security.web.util.matcher.RequestMatcher;
import org.springframework.util.Assert;

public final class WinssageSecurityMetadataSource implements
FilterInvocationSecurityMetadataSource {
protected final Log logger = LogFactory.getLog(getClass());
private SecurityMetadataSourceAdapter adapter = null;

// ~ Constructors
// ===================================================================================================
public WinssageSecurityMetadataSource(SecurityMetadataSourceAdapter adapter) {
this.adapter = adapter;
}

// ~ Methods
// ========================================================================================================

public Collection<ConfigAttribute> getAllConfigAttributes() {

return null;
}

public Collection<ConfigAttribute> getAttributes(Object object) {
Set<ConfigAttribute> resultAttributes = new HashSet<ConfigAttribute>();
ConfigAttribute resultAttr;

String url = ((FilterInvocation) object).getRequestUrl();

Collection<AccessAttribute> accessAttributes = adapter
.getAttributes(url);
if(null==accessAttributes||accessAttributes.size()==0)
return null;

for (AccessAttribute accessAttribute : accessAttributes) {
if (null == accessAttribute)
continue;
resultAttr = new SecurityConfig(accessAttribute.getAttribute());
resultAttributes.add(resultAttr);
}
<span style="white-space:pre">	</span>return resultAttributes;

}

public boolean supports(Class<?> clazz) {
return FilterInvocation.class.isAssignableFrom(clazz);
}
}

5、DefaultSecurityMetadataSourceAdapter

package com.winssage.spring.security;

import java.util.Collection;
import java.util.HashSet;

import org.springframework.security.access.ConfigAttribute;

import com.winssage.spring.security.access.intercept.AccessAttribute;
import com.winssage.spring.security.access.intercept.DefaultAccessAttribute;
import com.winssage.spring.security.access.intercept.SecurityMetadataSourceAdapter;

public class DefaultSecurityMetadataSourceAdapter implements
SecurityMetadataSourceAdapter {

@Override
public Collection<AccessAttribute> getAttributes(Object object) {

if(!(object instanceof String)) return null;

Collection<AccessAttribute> attributes=new HashSet<AccessAttribute>();
String url=(String)object;
if (!url.equals("/security/index")) {
return null;
}

AccessAttribute attr = new DefaultAccessAttribute("ROLE_ADMIN");
attributes.add(attr);
attr = new DefaultAccessAttribute("ROLE_USER");
attributes.add(attr);
return attributes;

}

}