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.jap", 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(url, resURL)) {
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。