最近在做项目遇到了权限管理，用户要求可以自己建立不同的角色对系统的资源进行控制， 不同的用户有不同的角色，又恰恰框架中用到了struts＋spring＋hibernate，要求在web层调用 业务逻辑层 时不考虑权限，web层可以控制用户的显示界面，逻辑层处理用户权限问题。
想来想去好像只有spring 的aop 可以做到，在调用到 接口 中的方法时，首先检查用户的权限，如果检查通过则继续执行，否则抛出异常。但是新的问题又出现了，如何在逻辑层上来得到当前用户的id，以致用户的 角色，总不能每次都要从web中传来一个 httprequest，或者 session 这类的吧。在网上看了很多资料，发现了acegi，恰好解决了以上的难题，具体的实现原理这里就不多说了，网上有很多相关资料。
说正题，首先来看看acegi 的官方 example ，我下载的是acegi-security-1.0.0-RC1,解压缩后可以看到acegi-security-sample-contacts-filter.war，打开配置文件有这样几句
1 <bean id="contactManagerSecurity" class="org.acegisecurity.intercept.method.aopalliance.MethodSecurityInterceptor">
2 <property name="authenticationManager"><ref bean="authenticationManager"/></property>
3 <property name="accessDecisionManager"><ref local="businessAccessDecisionManager"/></property>
4 <property name="afterInvocationManager"><ref local="afterInvocationManager"/></property>
5 <property name="objectDefinitionSource">
6 <value>
7 sample.contact.ContactManager.create=ROLE_USER
8 sample.contact.ContactManager.getAllRecipients=ROLE_USER
9 sample.contact.ContactManager.getAll=ROLE_USER,AFTER_ACL_COLLECTION_READ
10 sample.contact.ContactManager.getById=ROLE_USER,AFTER_ACL_READ
11 sample.contact.ContactManager.delete=ACL_CONTACT_DELETE
12 sample.contact.ContactManager.deletePermission=ACL_CONTACT_ADMIN
13 sample.contact.ContactManager.addPermission=ACL_CONTACT_ADMIN
14 </value>
15 </property>
16 </bean>
17
可以看到它是通过读配置文件来判断执行某个方法所需要的角色的，再看这几句
<bean id="filterInvocationInterceptor" class="org.acegisecurity.intercept.web.FilterSecurityInterceptor">
<property name="authenticationManager"><ref bean="authenticationManager"/></property>
<property name="accessDecisionManager"><ref local="httpRequestAccessDecisionManager"/></property>
<property name="objectDefinitionSource">
<value>
CONVERT_URL_TO_LOWERCASE_BEFORE_COMPARISON
PATTERN_TYPE_APACHE_ANT
/index.jsp=ROLE_ANONYMOUS,ROLE_USER
/hello.htm=ROLE_ANONYMOUS,ROLE_USER
/logoff.jsp=ROLE_ANONYMOUS,ROLE_USER
/switchuser.jsp=ROLE_SUPERVISOR
/j_acegi_switch_user=ROLE_SUPERVISOR
/acegilogin.jsp*=ROLE_ANONYMOUS,ROLE_USER
/**=ROLE_USER
</value>
</property>
</bean>
同样是将页面的访问权限写死在配置文件中，再来看看它的tag是如何处理的
<auth:authorize ifAnyGranted="ROLE_DELETE">
<a href="">删除</a>
</auth:authorize> 可见它是要求我们对链接或者其他资源的保护时提供 用户角色，可是既然角色是用户自己添加的我们又如何来写死在这里呢？
还有就是它对用户验证默认使用的是jdbc,即 JdbcDaoImpl
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource"><ref local="dataSource"/></property>
</bean> 而我们希望基于Hibernate的Dao来实现。
可见仅仅使用现有的acegi 是 无法满足我们项目开发的需求的。
解决方法: 1: 开发基于数据库的保护资源。
看过acegi的源代码就会知道，对保护资源的定义是通过实现ObjectDefinitionSource这个接口来实现的，而且acegi为我们提供了默认实现的抽象类
public abstract class AbstractMethodDefinitionSource
implements MethodDefinitionSource 
{
//~ Static fields/initializers =============================================
private static final Log logger = LogFactory.getLog(AbstractMethodDefinitionSource.class);
//~ Methods ================================================================
public ConfigAttributeDefinition getAttributes(Object object)
throws IllegalArgumentException {
Assert.notNull(object, "Object cannot be null");
if (object instanceof MethodInvocation) {
return this.lookupAttributes(((MethodInvocation) object).getMethod());
}
if (object instanceof JoinPoint) {
JoinPoint jp = (JoinPoint) object;
Class targetClazz = jp.getTarget().getClass();
String targetMethodName = jp.getStaticPart().getSignature().getName();
Class[] types = ((CodeSignature) jp.getStaticPart().getSignature())
.getParameterTypes();
if (logger.isDebugEnabled()) {
logger.debug("Target Class: " + targetClazz);
logger.debug("Target Method Name: " + targetMethodName);
for (int i = 0; i < types.length; i++) {
if (logger.isDebugEnabled()) {
logger.debug("Target Method Arg #" + i + ": "
+ types[i]);
}
}
}
try {
return this.lookupAttributes(targetClazz.getMethod(targetMethodName, types));
} catch (NoSuchMethodException nsme) {
throw new IllegalArgumentException("Could not obtain target method from JoinPoint: " + jp);
}
}
throw new IllegalArgumentException("Object must be a MethodInvocation or JoinPoint");
}
public boolean supports(Class clazz) {
return (MethodInvocation.class.isAssignableFrom(clazz)
|| JoinPoint.class.isAssignableFrom(clazz));
}
protected abstract ConfigAttributeDefinition lookupAttributes(Method method);
}
我们要做的就是实现它的
protected abstract ConfigAttributeDefinition lookupAttributes(Method method);方法，
以下是我的实现方法，大致思路是这样，通过由抽象类传来的Method 对象得到
调用这个方法的 包名，类名，方法名 也就是secureObjectName， 查询数据库并将结果映射为Function 也就是secureObject ，由于Function 与 Role 的多对多关系 可以得到 Function所对应的 Roles ，在将role 包装成GrantedAuthority （也就是acegi中的角色）。其中由于频繁的对数据库的查询 所以使用Ehcache 来作为缓存。
1 package sample.auth;
2
3 import java.lang.reflect.Method;
4 import java.util.ArrayList;
5 import java.util.Arrays;
6 import java.util.Collection;
7 import java.util.Iterator;
8 import java.util.List;
9 import java.util.Set;
10
11 import org.acegisecurity.ConfigAttributeDefinition;
12 import org.acegisecurity.ConfigAttributeEditor;
13 import org.acegisecurity.GrantedAuthority;
14 import org.acegisecurity.GrantedAuthorityImpl;
15 import org.acegisecurity.intercept.method.AbstractMethodDefinitionSource;
16 import org.springframework.util.Assert;
17
18 import sample.auth.cache.AuthorityBasedFunctionCache;
19 import sample.auth.cache.info.FunctionByNameCache;
20 import sample.dao.IBaseDao;
21 import sample.mappings.function.Function;
22 import sample.mappings.role.Role;
23
24 public class DatabaseDrivenMethodDefinitionSourcew extends
25 AbstractMethodDefinitionSource {
26
27 // baseDao 提供通过HIbenate对数据库操作的实现
28 private IBaseDao baseDao;
29 // AuthorityBasedFunctionCache 通过Function 查 Role 时缓存
30 private AuthorityBasedFunctionCache cache;
31 // FunctionByNameCache 由反射到的方法名查找 数据库对应的Function 时的缓存
32 private FunctionByNameCache functionCache;
33
34 public FunctionByNameCache getFunctionCache() {
35 return functionCache;
36 }
37
38 public void setFunctionCache(FunctionByNameCache functionCache) {
39 this.functionCache = functionCache;
40 }
41
42 protected ConfigAttributeDefinition lookupAttributes(Method mi) {
43
44 Assert.notNull(mi,"lookupAttrubutes in the DatabaseDrivenMethodDefinitionSourcew is null");
45 String secureObjectName=mi.getDeclaringClass().getName() +"."+ mi.getName();
46 //Function 为数据库中保护资源的映射
47 Function secureObject=functionCache.getFunctionByCache(secureObjectName);
48
49 if(secureObject==null)//if secure object not exist in database
50 {
51 secureObject=(Function)baseDao.loadByKey(Function.class, "protectfunction", secureObjectName);
52 functionCache.putFunctionInCache(secureObject);
53 }
54
55 if(secureObject==null)
56 Assert.notNull(secureObject,"secureObject(Function) not found in db");
57 //retrieving roles associated with this secure object
58
59 Collection roles = null;
60 GrantedAuthority[] grantedAuthoritys = cache.getAuthorityFromCache(secureObject.getName());
61 // 如果是第一次 cache 为空
62 if(grantedAuthoritys == null){
63
64 Set rolesSet = secureObject.getRoles();
65 Iterator it = rolesSet.iterator();
66 List list = new ArrayList();
67 while(it.hasNext()){
68
69 Role role = (Role)it.next();
70 GrantedAuthority g = new GrantedAuthorityImpl(role.getName());
71 list.add(g);
72 }
73 grantedAuthoritys = (GrantedAuthority[])list.toArray(new GrantedAuthority[0]);
74 cache.putAuthorityInCache(secureObject.getName(),grantedAuthoritys);
75 roles = Arrays.asList(grantedAuthoritys);
76 }else{
77
78 roles = Arrays.asList(grantedAuthoritys);
79 }
80
81 if(!roles.isEmpty()){
82 ConfigAttributeEditor configAttrEditor=new ConfigAttributeEditor();
83 StringBuffer rolesStr=new StringBuffer();
84 for(Iterator it = roles.iterator();it.hasNext();){
85 GrantedAuthority role=(GrantedAuthority)it.next();
86 rolesStr.append(role.getAuthority()).append(",");
87 }
88
89 configAttrEditor.setAsText( rolesStr.toString().substring(0,rolesStr.length()-1) );
90 ConfigAttributeDefinition configAttrDef=(ConfigAttributeDefinition)configAttrEditor.getValue();
91 return configAttrDef;
92 }
93
94 Assert.notEmpty(roles,"collection of roles is null or empty");
95 return null;
96
97
98 }
99
100 public Iterator getConfigAttributeDefinitions() {
101
102 return null;
103 }
104
105
106 public IBaseDao getBaseDao() {
107 return baseDao;
108 }
109
110
111 public void setBaseDao(IBaseDao baseDao) {
112 this.baseDao = baseDao;
113 }
114
115 public AuthorityBasedFunctionCache getCache() {
116 return cache;
117 }
118
119 public void setCache(AuthorityBasedFunctionCache cache) {
120 this.cache = cache;
121 }
122
123 }
124
2：定义 基于方法的 自定义标志
通过以上的分析 ， 要想使用acegi 做页面的显示控制仅仅靠角色（Role）是不行的，因为用户可能随时定义出新的角色，所以只能 基于方法（Function）的控制。可是acegi 只是提供了基于 角色的 接口GrantedAuthority ，怎么办? ，如法炮制。 首先定义出我们自己的GrantedFunction，实现也雷同 GrantedAuthorityImpl
1 package sample.auth;
2
3 import java.io.Serializable;
4 public class GrantedFunctionImpl implements GrantedFunction , Serializable{
5
6 private String function;
7
8 //~ Constructors ===========================================================
9
10 public GrantedFunctionImpl(String function) {
11 super();
12 this.function = function;
13 }
14
15 protected GrantedFunctionImpl() {
16 throw new IllegalArgumentException("Cannot use default constructor");
17 }
18
19 //~ Methods ================================================================
20
21 public String getFunction() {
22 return this.function;
23 }
24
25 public boolean equals(Object obj) {
26 if (obj instanceof String) {
27 return obj.equals(this.function);
28 }
29
30 if (obj instanceof GrantedFunction) {
31 GrantedFunction attr = (GrantedFunction) obj;
32
33 return this.function.equals(attr.getFunction());
34 }
35
36 return false;
37 }
38
39 public int hashCode() {
40 return this.function.hashCode();
41 }
42
43 public String toString() {
44 return this.function;
45 }
46
47 }
48
以下是我的标志实现，大致思路是 根据 页面 的传来的 方法名（即 FunctionName）查询出对应的Functions，并且包装成grantedFunctions ，然后根据用户的角色查询出用户对应的Functions ，再取这两个集合的交集，最后再根据这个集合是否为空判断是否显示标志体的内容。
1 package sample.auth;
2 import java.util.Arrays;
3 import java.util.Collection;
4 import java.util.Collections;
5 import java.util.HashSet;
6 import java.util.Iterator;
7 import java.util.List;
8 import java.util.Set;
9
10 import javax.servlet.jsp.JspException;
11 import javax.servlet.jsp.tagext.Tag;
12 import javax.servlet.jsp.tagext.TagSupport;
13
14 import org.acegisecurity.Authentication;
15 import org.acegisecurity.GrantedAuthority;
16 import org.acegisecurity.context.SecurityContextHolder;
17 import org.springframework.util.StringUtils;
18 import org.springframework.web.util.ExpressionEvaluationUtils;
19
20 import sample.web.action.AppContext;
21 /**
22 *
23 * @author limq
24 *
25 */
26 public class AuthorizeActionTag extends TagSupport{
27
28 private String ifAllGranted = "";
29 private String ifAnyGranted = "";
30 private String ifNotGranted = "";
31
32 public void setIfAllGranted(String ifAllGranted) throws JspException {
33 this.ifAllGranted = ifAllGranted;
34 }
35
36 public String getIfAllGranted() {
37 return ifAllGranted;
38 }
39
40 public void setIfAnyGranted(String ifAnyGranted) throws JspException {
41 this.ifAnyGranted = ifAnyGranted;
42 }
43
44 public String getIfAnyGranted() {
45 return ifAnyGranted;
46 }
47
48 public void setIfNotGranted(String ifNotGranted) throws JspException {
49 this.ifNotGranted = ifNotGranted;
50 }
51
52 public String getIfNotGranted() {
53 return ifNotGranted;
54 }
55
56 public int doStartTag() throws JspException {
57 if (((null == ifAllGranted) || "".equals(ifAllGranted))
58 && ((null == ifAnyGranted) || "".equals(ifAnyGranted))
59 && ((null == ifNotGranted) || "".equals(ifNotGranted))) {
60 return Tag.SKIP_BODY;
61 }
62
63 final Collection granted = getPrincipalFunctionByAuthorities();
64
65 final String evaledIfNotGranted = ExpressionEvaluationUtils
66 .evaluateString("ifNotGranted", ifNotGranted, pageContext);
67
68 if ((null != evaledIfNotGranted) && !"".equals(evaledIfNotGranted)) {
69 Set grantedCopy = retainAll(granted,
70 parseSecurityString(evaledIfNotGranted));
71
72 if (!grantedCopy.isEmpty()) {
73 return Tag.SKIP_BODY;
74 }
75 }
76
77 final String evaledIfAllGranted = ExpressionEvaluationUtils
78 .evaluateString("ifAllGranted", ifAllGranted, pageContext);
79
80 if ((null != evaledIfAllGranted) && !"".equals(evaledIfAllGranted)) {
81 if (!granted.containsAll(parseSecurityString(evaledIfAllGranted))) {
82 return Tag.SKIP_BODY;
83 }
84 }
85
86 final String evaledIfAnyGranted = ExpressionEvaluationUtils
87 .evaluateString("ifAnyGranted", ifAnyGranted, pageContext);
88
89 if ((null != evaledIfAnyGranted) && !"".equals(evaledIfAnyGranted)) {
90 Set grantedCopy = retainAll(granted,
91 parseSecurityString(evaledIfAnyGranted));
92
93 if (grantedCopy.isEmpty()) {
94 return Tag.SKIP_BODY;
95 }
96 }
97
98 return Tag.EVAL_BODY_INCLUDE;
99 }
100 /**
101 * 得到用户的Authentication，并且从Authentication中获得 Authorities，进而得到 授予用户的 Function
102 * @return
103 */
104 private Collection getPrincipalFunctionByAuthorities() {
105
106
107 Authentication currentUser = SecurityContextHolder.getContext()
