Spring Security 3.x 出来一段时间了，跟Acegi是大不同了，与2.x的版本也有一些小小的区别，网上有一些文档，也有人翻译Spring Security 3.x的guide，但通过阅读guide，无法马上就能很容易的实现一个完整的实例。
我花了点儿时间，根据以前的实战经验，整理了一份完整的入门教程，供需要的朋友们参考。
1，建一个web project，并导入所有需要的lib，这步就不多讲了。
2，配置web.xml，使用Spring的机制装载：
<?xml version="1.0" encoding="UTF-8"?><web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"> <context-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:applicationContext*.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> <welcome-file-list> <welcome-file>login.jsp</welcome-file> </welcome-file-list></web-app>
这个文件中的内容我相信大家都很熟悉了，不再多说了。
2，来看看applicationContext-security.xml这个配置文件，关于Spring Security的配置均在其中：
<?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-3.0.xsd"> <http access-denied-page="/403.jsp"><!-- 当访问被拒绝时，会转到403.jsp --> <intercept-url pattern="/login.jsp" filters="none" /> <form-login login-page="/login.jsp" authentication-failure-url="/login.jsp?error=true" default-target-url="/index.jsp" /> <logout logout-success-url="/login.jsp" /> <http-basic /> <!-- 增加一个filter，这点与Acegi是不一样的，不能修改默认的filter了，这个filter位于FILTER_SECURITY_INTERCEPTOR之前 --> <custom-filter before="FILTER_SECURITY_INTERCEPTOR" ref="myFilter" /> </http> <!-- 一个自定义的filter，必须包含authenticationManager,accessDecisionManager,securityMetadataSource三个属性， 我们的所有控制将在这三个类中实现，解释详见具体配置 --> <beans:bean id="myFilter" class="com.robin.erp.fwk.security.MyFilterSecurityInterceptor"> <beans:property name="authenticationManager" ref="authenticationManager" /> <beans:property name="accessDecisionManager" ref="myAccessDecisionManagerBean" /> <beans:property name="securityMetadataSource" ref="securityMetadataSource" /> </beans:bean> <!-- 认证管理器，实现用户认证的入口，主要实现UserDetailsService接口即可 --> <authentication-manager alias="authenticationManager"> <authentication-provider user-service-ref="myUserDetailService"> <!-- 如果用户的密码采用加密的话，可以加点“盐” <password-encoder hash="md5" /> --> </authentication-provider> </authentication-manager> <beans:bean id="myUserDetailService" class="com.robin.erp.fwk.security.MyUserDetailService" /> <!-- 访问决策器，决定某个用户具有的角色，是否有足够的权限去访问某个资源 --> <beans:bean id="myAccessDecisionManagerBean" class="com.robin.erp.fwk.security.MyAccessDecisionManager"> </beans:bean> <!-- 资源源数据定义，即定义某一资源可以被哪些角色访问 --> <beans:bean id="securityMetadataSource" class="com.robin.erp.fwk.security.MyInvocationSecurityMetadataSource" /></beans:beans>
3，来看看自定义filter的实现：
package com.robin.erp.fwk.security;import java.io.IOException;import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import org.springframework.security.access.SecurityMetadataSource;import org.springframework.security.access.intercept.AbstractSecurityInterceptor;import org.springframework.security.access.intercept.InterceptorStatusToken;import org.springframework.security.web.FilterInvocation;import org.springframework.security.web.access.intercept.FilterInvocationSecurityMetadataSource;public class MyFilterSecurityInterceptor extends AbstractSecurityInterceptor
implements Filter 
{
private FilterInvocationSecurityMetadataSource securityMetadataSource; // ~ Methods // ========================================================================================================
/** *//** * Method that is actually called by the filter chain. Simply delegates to * the {@link #invoke(FilterInvocation)} method. * * @param request * the servlet request * @param response * the servlet response * @param chain * the filter chain * * @throws IOException * if the filter chain fails * @throws ServletException * if the filter chain fails
*/ public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { FilterInvocation fi = new FilterInvocation(request, response, chain); invoke(fi); } public FilterInvocationSecurityMetadataSource getSecurityMetadataSource() { return this.securityMetadataSource; } public Class<? extends Object> getSecureObjectClass() { return FilterInvocation.class; } public void invoke(FilterInvocation fi) throws IOException, ServletException { InterceptorStatusToken token = super.beforeInvocation(fi); try { fi.getChain().doFilter(fi.getRequest(), fi.getResponse()); } finally { super.afterInvocation(token, null); } } public SecurityMetadataSource obtainSecurityMetadataSource() { return this.securityMetadataSource; } public void setSecurityMetadataSource( FilterInvocationSecurityMetadataSource newSource) { this.securityMetadataSource = newSource; } @Override public void destroy() { } @Override public void init(FilterConfig arg0) throws ServletException { }
}
最核心的代码就是invoke方法中的InterceptorStatusToken token = super.beforeInvocation(fi);这一句，即在执行doFilter之前，进行权限的检查，而具体的实现已经交给accessDecisionManager了，下文中会讲述。
4，来看看authentication-provider的实现：
package com.robin.erp.fwk.security;import java.util.ArrayList;import java.util.Collection;import org.springframework.dao.DataAccessException;import org.springframework.security.core.GrantedAuthority;import org.springframework.security.core.authority.GrantedAuthorityImpl;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;public class MyUserDetailService implements UserDetailsService { @Override public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException, DataAccessException { Collection<GrantedAuthority> auths=new ArrayList<GrantedAuthority>(); GrantedAuthorityImpl auth2=new GrantedAuthorityImpl("ROLE_ADMIN"); auths.add(auth2); if(username.equals("robin1")){ auths=new ArrayList<GrantedAuthority>(); GrantedAuthorityImpl auth1=new GrantedAuthorityImpl("ROLE_ROBIN"); auths.add(auth1); } // User(String username, String password, boolean enabled, boolean accountNonExpired,// boolean credentialsNonExpired, boolean accountNonLocked, Collection<GrantedAuthority> authorities) { User user = new User(username, "robin", true, true, true, true, auths); return user; } }
在这个类中，你就可以从数据库中读入用户的密码，角色信息，是否锁定，账号是否过期等，我想这么简单的代码就不再多解释了。
5，对于资源的访问权限的定义，我们通过实现FilterInvocationSecurityMetadataSource这个接口来初始化数据。
package com.robin.erp.fwk.security;import java.util.ArrayList;import java.util.Collection;import java.util.HashMap;import java.util.Iterator;import java.util.Map;import org.springframework.security.access.ConfigAttribute;import org.springframework.security.access.SecurityConfig;import org.springframework.security.web.FilterInvocation;import org.springframework.security.web.access.intercept.FilterInvocationSecurityMetadataSource;import org.springframework.security.web.util.AntUrlPathMatcher;import org.springframework.security.web.util.UrlMatcher;/** *//** * * 此类在初始化时，应该取到所有资源及其对应角色的定义 * * @author Robin * */public class MyInvocationSecurityMetadataSource implements FilterInvocationSecurityMetadataSource { private UrlMatcher urlMatcher = new AntUrlPathMatcher();; private static Map<String, Collection<ConfigAttribute>> resourceMap = null; public MyInvocationSecurityMetadataSource() { loadResourceDefine(); } private void loadResourceDefine() { resourceMap = new HashMap<String, Collection<ConfigAttribute>>(); Collection<ConfigAttribute> atts = new ArrayList<ConfigAttribute>(); ConfigAttribute ca = new SecurityConfig("ROLE_ADMIN"); atts.add(ca); resourceMap.put("/index.jsp", atts); resourceMap.put("/i.jsp", atts); } // According to a URL, Find out permission configuration of this URL. public Collection<ConfigAttribute> getAttributes(Object object) throws IllegalArgumentException { // guess object is a URL. String url = ((FilterInvocation)object).getRequestUrl(); Iterator<String> ite = resourceMap.keySet().iterator(); while (ite.hasNext()) { String resURL = ite.next(); if (urlMatcher.pathMatchesUrl(resURL, url)) { return resourceMap.get(resURL); } } return null; } public boolean supports(Class<?> clazz) { return true; } public Collection<ConfigAttribute> getAllConfigAttributes() { return null; }}
看看loadResourceDefine方法，我在这里，假定index.jsp和i.jsp这两个资源，需要ROLE_ADMIN角色的用户才能访问。
这个类中，还有一个最核心的地方，就是提供某个资源对应的权限定义，即getAttributes方法返回的结果。注意，我例子中使用的是AntUrlPathMatcher这个path matcher来检查URL是否与资源定义匹配，事实上你还要用正则的方式来匹配，或者自己实现一个matcher。
6，剩下的就是最终的决策了，make a decision，其实也很容易，呵呵。
package com.robin.erp.fwk.security;import java.util.Collection;import java.util.Iterator;import org.springframework.security.access.AccessDecisionManager;import org.springframework.security.access.AccessDeniedException;import org.springframework.security.access.ConfigAttribute;import org.springframework.security.access.SecurityConfig;import org.springframework.security.authentication.InsufficientAuthenticationException;import org.springframework.security.core.Authentication;import org.springframework.security.core.GrantedAuthority;public class MyAccessDecisionManager implements AccessDecisionManager { //In this method, need to compare authentication with configAttributes. // 1, A object is a URL, a filter was find permission configuration by this URL, and pass to here. // 2, Check authentication has attribute in permission configuration (configAttributes) // 3, If not match corresponding authentication, throw a AccessDeniedException. public void decide(Authentication authentication, Object object, Collection<ConfigAttribute> configAttributes) throws AccessDeniedException, InsufficientAuthenticationException { if(configAttributes == null){ return ; } System.out.println(object.toString()); //object is a URL. Iterator<ConfigAttribute> ite=configAttributes.iterator(); while(ite.hasNext()){ ConfigAttribute ca=ite.next(); String needRole=((SecurityConfig)ca).getAttribute(); for(GrantedAuthority ga:authentication.getAuthorities()){ if(needRole.equals(ga.getAuthority())){ //ga is user's role. return; } } } throw new AccessDeniedException("no right"); } @Override public boolean supports(ConfigAttribute attribute) { // TODO Auto-generated method stub return true; } @Override public boolean supports(Class<?> clazz) { return true; }}在这个类中，最重要的是decide方法，如果不存在对该资源的定义，直接放行；否则，如果找到正确的角色，即认为拥有权限，并放行，否则throw new AccessDeniedException("no right");这样，就会进入上面提到的403.jsp页面。