【Shiro学习之七】shiro缓存

apahce shiro:1.6.0

Shiro 提供了类似于 Spring 的 Cache 抽象，即 Shiro 本身不实现 Cache，但是对 Cache 进行了又抽象，方便更换不同的底层 Cache 实现。
一、相关组件
1、Cache接口

2、CacheManager接口

3、CacheManagerAware接口用于注入CacheManager
Shiro内部相应的组件DefaultSecurityManager会自动检测相应的对象（如Realm）是否实现了CacheManagerAware并自动注入相应的CacheManager。

二、Realm 缓存

Shiro 提供了 CachingRealm，其实现了 CacheManagerAware 接口，提供了缓存的一些基础实现；另外 AuthenticatingRealm 及 AuthorizingRealm 分别提供了对 AuthenticationInfo和AuthorizationInfo 信息的缓存。
当用户修改密码或者修改权限后需要将缓存中的 AuthenticationInfo和AuthorizationInfo清除掉。

package com.github.zhangkaitao.shiro.chapter11.realm;

import com.github.zhangkaitao.shiro.chapter11.entity.User;
import com.github.zhangkaitao.shiro.chapter11.service.UserService;
import com.github.zhangkaitao.shiro.chapter11.service.UserServiceImpl;
import org.apache.shiro.authc.*;
import org.apache.shiro.authz.AuthorizationInfo;
import org.apache.shiro.authz.SimpleAuthorizationInfo;
import org.apache.shiro.realm.AuthorizingRealm;
import org.apache.shiro.subject.PrincipalCollection;
import org.apache.shiro.util.ByteSource;

/**
 * <p>User: Zhang Kaitao
 * <p>Date: 14-1-28
 * <p>Version: 1.0
 */
public class UserRealm extends AuthorizingRealm {

    private UserService userService = new UserServiceImpl();

    @Override
    protected AuthorizationInfo doGetAuthorizationInfo(PrincipalCollection principals) {
        String username = (String)principals.getPrimaryPrincipal();

        SimpleAuthorizationInfo authorizationInfo = new SimpleAuthorizationInfo();
        authorizationInfo.setRoles(userService.findRoles(username));
        authorizationInfo.setStringPermissions(userService.findPermissions(username));
        return authorizationInfo;
    }

    @Override
    protected AuthenticationInfo doGetAuthenticationInfo(AuthenticationToken token) throws AuthenticationException {

        String username = (String)token.getPrincipal();

        User user = userService.findByUsername(username);
        if(user == null) {
            throw new UnknownAccountException();//没找到帐号
        }

        if(Boolean.TRUE.equals(user.getLocked())) {
            throw new LockedAccountException(); //帐号锁定
        }

        //交给AuthenticatingRealm使用CredentialsMatcher进行密码匹配，如果觉得人家的不好可以自定义实现
        SimpleAuthenticationInfo authenticationInfo = new SimpleAuthenticationInfo(
                user.getUsername(), //用户名
                user.getPassword(), //密码
                ByteSource.Util.bytes(user.getCredentialsSalt()),//salt=username+salt
                getName()  //realm name
        );
        return authenticationInfo;
    }

    @Override
    public void clearCachedAuthorizationInfo(PrincipalCollection principals) {
        super.clearCachedAuthorizationInfo(principals);
    }

    @Override
    public void clearCachedAuthenticationInfo(PrincipalCollection principals) {
        super.clearCachedAuthenticationInfo(principals);
    }

    @Override
    public void clearCache(PrincipalCollection principals) {
        super.clearCache(principals);
    }

    public void clearAllCachedAuthorizationInfo() {
        getAuthorizationCache().clear();
    }

    public void clearAllCachedAuthenticationInfo() {
        getAuthenticationCache().clear();
    }

    public void clearAllCache() {
        clearAllCachedAuthenticationInfo();
        clearAllCachedAuthorizationInfo();
    }

}

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在某些清空下这种方式可能不是最好的选择，可以考虑直接废弃 Shiro 的缓存，然后自己通过如 AOP 机制实现自己的缓存；可以参考：

https://github.com/zhangkaitao/es/tree/master/web/src/main/java/com/sishuok/es/extra/aop
另外如果和 Spring 集成时可以考虑直接使用 Spring 的 Cache 抽象，可以考虑使用SpringCacheManagerWrapper，其对 Spring Cache 进行了包装，转换为 Shiro 的 CacheManager实现：
https://github.com/zhangkaitao/es/blob/master/web/src/main/java/org/apache/shiro/cache/spring/SpringCacheManagerWrapper.java

三、Session 缓存

securityManager实现了SessionsSecurityManager，其会自动判断 SessionManager是否实现了CacheManagerAware 接口，如果实现了会把 CacheManager 设置给它。然后sessionManager会判断相应的sessionDAO（如继承自 CachingSessionDAO）是否实现了CacheManagerAware，如果实现了会把 CacheManager 设置给它。

package com.github.zhangkaitao.shiro.chapter11.session.dao;

import com.github.zhangkaitao.shiro.chapter11.JdbcTemplateUtils;
import com.github.zhangkaitao.shiro.chapter11.SerializableUtils;
import org.apache.shiro.session.Session;
import org.apache.shiro.session.mgt.ValidatingSession;
import org.apache.shiro.session.mgt.eis.CachingSessionDAO;
import org.springframework.jdbc.core.JdbcTemplate;

import java.io.Serializable;
import java.util.List;

/**
 * <p>User: Zhang Kaitao
 * <p>Date: 14-2-8
 * <p>Version: 1.0
 */
public class MySessionDAO extends CachingSessionDAO {

    private JdbcTemplate jdbcTemplate = JdbcTemplateUtils.jdbcTemplate();

    @Override
    protected Serializable doCreate(Session session) {
        Serializable sessionId = generateSessionId(session);
        assignSessionId(session, sessionId);
        String sql = "insert into sessions(id, session) values(?,?)";
        jdbcTemplate.update(sql, sessionId, SerializableUtils.serialize(session));
        return session.getId();
    }
    @Override
    protected void doUpdate(Session session) {
        if(session instanceof ValidatingSession && !((ValidatingSession)session).isValid()) {
            return; //如果会话过期/停止 没必要再更新了
        }
        String sql = "update sessions set session=? where id=?";
        jdbcTemplate.update(sql, SerializableUtils.serialize(session), session.getId());
    }
    @Override
    protected void doDelete(Session session) {
        String sql = "delete from sessions where id=?";
        jdbcTemplate.update(sql, session.getId());
    }
    @Override
    protected Session doReadSession(Serializable sessionId) {
        String sql = "select session from sessions where id=?";
        List<String> sessionStrList = jdbcTemplate.queryForList(sql, String.class, sessionId);
        if(sessionStrList.size() == 0) return null;
        return SerializableUtils.deserialize(sessionStrList.get(0));
    }
}

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