Apache shiro集群实现 （七）分布式集群系统下---cache共享

Apache shiro集群实现 （一） shiro入门介绍

Apache shiro集群实现 （二） shiro 的INI配置

Apache shiro集群实现 （三）shiro身份认证（Shiro Authentication）

Apache shiro集群实现 （四）shiro授权（Authentication）--访问控制

Apache shiro集群实现 （五）分布式集群系统下的高可用session解决方案

Apache shiro集群实现 （六）分布式集群系统下的高可用session解决方案---Session共享

Apache shiro集群实现（七）分布式集群系统下---cache共享

Apache shiro集群实现 （八） web集群时session同步的3种方法

上一篇已经解决了第一个问题，session的共享，现在我们解决第二个问题cache的共享。

先看下spring的配置文件，上一篇已经提到过了

<span style="font-size:18px;"><bean id="securityManager" class="org.apache.shiro.web.mgt.DefaultWebSecurityManager" depends-on="userRepository,roleRepository">
    <property name="sessionManager" ref="defaultWebSessionManager" />
    <property name="realm" ref="shiroDbRealm" />
    <property name="cacheManager" ref="memoryConstrainedCacheManager" />
</bean>
<bean id="memoryConstrainedCacheManager" class="org.apache.shiro.cache.MemoryConstrainedCacheManager" /></span>

这里cacheManager我们注入了shiro自定的本机内存实现的cacheManager类，当然，这肯定不满足我们集群的需要，所以我们要自己实现cacheManager类，这里我还是用了redis作为cache的存储，先创建RedisCacheManager实现类

<span style="font-size:18px;">package com.tgb.itoo.authority.cache;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

import org.apache.shiro.cache.Cache;
import org.apache.shiro.cache.CacheException;
import org.apache.shiro.cache.CacheManager;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class RedisCacheManager implements CacheManager{

	private static final Logger logger = LoggerFactory
			.getLogger(RedisCacheManager.class);

	// fast lookup by name map
	private final ConcurrentMap<String, Cache> caches = new ConcurrentHashMap<String, Cache>();

	private RedisManager redisManager;

	/**
	 * The Redis key prefix for caches
	 */
	private String keyPrefix = "shiro_redis_cache:";

	/**
	 * Returns the Redis session keys
	 * prefix.
	 * @return The prefix
	 */
	public String getKeyPrefix() {
		return keyPrefix;
	}

	/**
	 * Sets the Redis sessions key
	 * prefix.
	 * @param keyPrefix The prefix
	 */
	public void setKeyPrefix(String keyPrefix) {
		this.keyPrefix = keyPrefix;
	}

	@Override
	public <K, V> Cache<K, V> getCache(String name) throws CacheException {
		logger.debug("获取名称为: " + name + " 的RedisCache实例");

		Cache c = caches.get(name);

		if (c == null) {

			// initialize the Redis manager instance
			redisManager.init();

			// create a new cache instance
			c = new RedisCache<K, V>(redisManager, keyPrefix);

			// add it to the cache collection
			caches.put(name, c);
		}
		return c;
	}

	public RedisManager getRedisManager() {
		return redisManager;
	}

	public void setRedisManager(RedisManager redisManager) {
		this.redisManager = redisManager;
	}
}
</span>

当然，这里仅仅是getCache，我第一次看源码时，也有这样的疑问，cache的add、remove等等方法在哪里实现呢？我们继续看看shiro的源码就会知道答案了

这个是自己relm的AuthorizingRealm中的方法

<span style="font-size:18px;">    protected AuthorizationInfo getAuthorizationInfo(PrincipalCollection principals) {  

            if (principals == null) {
                return null;
            }  

            AuthorizationInfo info = null;  

            if (log.isTraceEnabled()) {
                log.trace("Retrieving AuthorizationInfo for principals [" + principals + "]");
            }  

            Cache<Object, AuthorizationInfo> cache = getAvailableAuthorizationCache();
            if (cache != null) {
                if (log.isTraceEnabled()) {
                    log.trace("Attempting to retrieve the AuthorizationInfo from cache.");
                }
                Object key = getAuthorizationCacheKey(principals);
                info = cache.get(key);
                if (log.isTraceEnabled()) {
                    if (info == null) {
                        log.trace("No AuthorizationInfo found in cache for principals [" + principals + "]");
                    } else {
                        log.trace("AuthorizationInfo found in cache for principals [" + principals + "]");
                    }
                }
            }
            if (info == null) {
                // Call template method if the info was not found in a cache
                info = <STRONG>doGetAuthorizationInfo</STRONG>(principals);
                // If the info is not null and the cache has been created, then cache the authorization info.
                if (info != null && cache != null) {
                    if (log.isTraceEnabled()) {
                        log.trace("Caching authorization info for principals: [" + principals + "].");
                    }
                    Object key = getAuthorizationCacheKey(principals);
                    <STRONG>cache.put</STRONG>(key, info);
                }
            }
            return info;
        }  </span>

如果大家去查查引入就知道我们自定义relm要实现一个叫做doGetAuthorizationInfo()的方法，它的作用是查询授权信息，我们注意加粗的2行，发现其实cache的put方法其实才是cache存储的核心类，其实现都在cache中，所以我们需要实现自己的cache，创建RedisCache类

<span style="font-size:18px;">package com.tgb.itoo.authority.cache;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.apache.shiro.cache.Cache;
import org.apache.shiro.cache.CacheException;
import org.apache.shiro.util.CollectionUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class RedisCache<K,V> implements Cache<K,V> {

	private Logger logger = LoggerFactory.getLogger(this.getClass());

	/**
     * The wrapped Jedis instance.
     */
	private RedisManager cache;

	/**
	 * The Redis key prefix for the sessions
	 */
	private String keyPrefix = "shiro_redis_session:";

	/**
	 * Returns the Redis session keys
	 * prefix.
	 * @return The prefix
	 */
	public String getKeyPrefix() {
		return keyPrefix;
	}

	/**
	 * Sets the Redis sessions key
	 * prefix.
	 * @param keyPrefix The prefix
	 */
	public void setKeyPrefix(String keyPrefix) {
		this.keyPrefix = keyPrefix;
	}

	/**
	 * 通过一个JedisManager实例构造RedisCache
	 */
	public RedisCache(RedisManager cache){
		 if (cache == null) {
	         throw new IllegalArgumentException("Cache argument cannot be null.");
	     }
	     this.cache = cache;
	}

	/**
	 * Constructs a cache instance with the specified
	 * Redis manager and using a custom key prefix.
	 * @param cache The cache manager instance
	 * @param prefix The Redis key prefix
	 */
	public RedisCache(RedisManager cache,
				String prefix){

		this( cache );

		// set the prefix
		this.keyPrefix = prefix;
	}

	/**
	 * 获得byte[]型的key
	 * @param key
	 * @return
	 */
	private byte[] getByteKey(K key){
		if(key instanceof String){
			String preKey = this.keyPrefix + key;
    		return preKey.getBytes();
    	}else{
    		return SerializeUtils.serialize(key);
    	}
	}

	@Override
	public V get(K key) throws CacheException {
		logger.debug("根据key从Redis中获取对象 key [" + key + "]");
		try {
			if (key == null) {
	            return null;
	        }else{
	        	byte[] rawValue = cache.get(getByteKey(key));
	        	@SuppressWarnings("unchecked")
				V value = (V)SerializeUtils.deserialize(rawValue);
	        	return value;
	        }
		} catch (Throwable t) {
			throw new CacheException(t);
		}

	}

	@Override
	public V put(K key, V value) throws CacheException {
		logger.debug("根据key从存储 key [" + key + "]");
		 try {
			 	cache.set(getByteKey(key), SerializeUtils.serialize(value));
	            return value;
	        } catch (Throwable t) {
	            throw new CacheException(t);
	        }
	}

	@Override
	public V remove(K key) throws CacheException {
		logger.debug("从redis中删除 key [" + key + "]");
		try {
            V previous = get(key);
            cache.del(getByteKey(key));
            return previous;
        } catch (Throwable t) {
            throw new CacheException(t);
        }
	}

	@Override
	public void clear() throws CacheException {
		logger.debug("从redis中删除所有元素");
		try {
            cache.flushDB();
        } catch (Throwable t) {
            throw new CacheException(t);
        }
	}

	@Override
	public int size() {
		try {
			Long longSize = new Long(cache.dbSize());
            return longSize.intValue();
        } catch (Throwable t) {
            throw new CacheException(t);
        }
	}

	@SuppressWarnings("unchecked")
	@Override
	public Set<K> keys() {
		try {
            Set<byte[]> keys = cache.keys(this.keyPrefix + "*");
            if (CollectionUtils.isEmpty(keys)) {
            	return Collections.emptySet();
            }else{
            	Set<K> newKeys = new HashSet<K>();
            	for(byte[] key:keys){
            		newKeys.add((K)key);
            	}
            	return newKeys;
            }
        } catch (Throwable t) {
            throw new CacheException(t);
        }
	}

	@Override
	public Collection<V> values() {
		try {
            Set<byte[]> keys = cache.keys(this.keyPrefix + "*");
            if (!CollectionUtils.isEmpty(keys)) {
                List<V> values = new ArrayList<V>(keys.size());
                for (byte[] key : keys) {
                    @SuppressWarnings("unchecked")
					V value = get((K)key);
                    if (value != null) {
                        values.add(value);
                    }
                }
                return Collections.unmodifiableList(values);
            } else {
                return Collections.emptyList();
            }
        } catch (Throwable t) {
            throw new CacheException(t);
        }
	}
}
</span>

最后修改spring配置文件

<span style="font-size:18px;"><!-- 第三：shiro管理中心类 start-李社河 -->
	<bean id="securityManager" class="org.apache.shiro.web.mgt.DefaultWebSecurityManager">
		<property name="realm" ref="shiroRealm"></property>
		<property name="sessionMode" value="http"></property>
		<property name="subjectFactory" ref="casSubjectFactory"></property>
		<!-- ehcahe缓存shiro自带 -->
		<!-- <property name="cacheManager" ref="shiroEhcacheManager"></property> -->

		<!-- redis缓存 -->
		<property name="cacheManager" ref="redisCacheManager" />

		<!-- sessionManager -->
		<property name="sessionManager" ref="sessionManager"></property>
	</bean></span>

这样就完成了整个shiro集群的配置