Spring Security 3.x 出來一段時間了，跟Acegi是大不同了，與2.x的版本也有一些小小的區別，網上有一些文檔，也有人翻譯Spring Security 3.x的guide，但通過閱讀guide，無法馬上就能很容易的實現一個完整的實例。
我花了點兒時間，根據以前的實戰經驗，整理了一份完整的入門教程，供需要的朋友們參考。
1，建一個web project，并導入所有需要的lib，這步就不多講了。
2，配置web.xml，使用Spring的機制裝載：
<?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>
這個文件中的內容我相信大家都很熟悉了，不再多說了。
2，來看看applicationContext-security.xml這個配置文件，關于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"><!-- 當訪問被拒絕時，會轉到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 />
<!-- 增加一個filter，這點與Acegi是不一樣的，不能修改默認的filter了，這個filter位于FILTER_SECURITY_INTERCEPTOR之前 -->
<custom-filter before="FILTER_SECURITY_INTERCEPTOR"
ref="myFilter" />
</http>
<!-- 一個自定義的filter，必須包含authenticationManager,accessDecisionManager,securityMetadataSource三個屬性，
我們的所有控制將在這三個類中實現，解釋詳見具體配置 -->
<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>
<!-- 認證管理器，實現用戶認證的入口，主要實現UserDetailsService接口即可 -->
<authentication-manager alias="authenticationManager">
<authentication-provider
user-service-ref="myUserDetailService">
<!-- 如果用戶的密碼采用加密的話，可以加點“鹽”
<password-encoder hash="md5" />
-->
</authentication-provider>
</authentication-manager>
<beans:bean id="myUserDetailService"
class="com.robin.erp.fwk.security.MyUserDetailService" />
<!-- 訪問決策器，決定某個用戶具有的角色，是否有足夠的權限去訪問某個資源 -->
<beans:bean id="myAccessDecisionManagerBean"
class="com.robin.erp.fwk.security.MyAccessDecisionManager">
</beans:bean>
<!-- 資源源數據定義，即定義某一資源可以被哪些角色訪問 -->
<beans:bean id="securityMetadataSource"
class="com.robin.erp.fwk.security.MyInvocationSecurityMetadataSource" />
</beans:beans>
3，來看看自定義filter的實現：
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 {
}
}
最核心的代碼就是invoke方法中的InterceptorStatusToken token = super.beforeInvocation(fi);這一句，即在執行doFilter之前，進行權限的檢查，而具體的實現已經交給accessDecisionManager了，下文中會講述。
4，來看看authentication-provider的實現：
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;
}
}
在這個類中，你就可以從數據庫中讀入用戶的密碼，角色信息，是否鎖定，賬號是否過期等，我想這么簡單的代碼就不再多解釋了。
5，對于資源的訪問權限的定義，我們通過實現FilterInvocationSecurityMetadataSource這個接口來初始化數據。
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;
/** *//**
*
* 此類在初始化時，應該取到所有資源及其對應角色的定義
*
* @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，我在這里，假定index.jsp和i.jsp這兩個資源，需要ROLE_ADMIN角色的用戶才能訪問。
這個類中，還有一個最核心的地方，就是提供某個資源對應的權限定義，即getAttributes方法返回的結果。注意，我例子中使用的是AntUrlPathMatcher這個path matcher來檢查URL是否與資源定義匹配，事實上你還要用正則的方式來匹配，或者自己實現一個matcher。
6，剩下的就是最終的決策了，make a decision，其實也很容易，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;
}
}
在這個類中，最重要的是decide方法，如果不存在對該資源的定義，直接放行；否則，如果找到正確的角色，即認為擁有權限，并放行，否則throw new AccessDeniedException("no right");這樣，就會進入上面提到的403.jsp頁面。