spring mvc @cache+redis 整合

以你之姓@ 2022-05-18 05:16 152阅读 0赞

**一.spring cache和cache+redis的区别**  
**1. 缓存级别不同**  
Spring cache是代码级的缓存，他一般是使用一个ConcurrentMap。也就是说实际上还是是使用JVM的内存来缓存对象的，那么肯定会造成大量的内存消耗。但是使用方便。  
Redis 作为一个缓存服务器，是内存级的缓存。它是使用单纯的内存来进行缓存。

**2. sprirng cache+redis的好处**  
那么Spring cache +redis的好处显而易见了。既可以很方便的缓存对象，同时用来缓存的内存的是使用redis的内存，不会消耗JVM的内存，提升了性能。当然这里Redis不是必须的，换成其他的缓存服务器一样可以，只要实现Spring的Cache类，并配置到XML里面就行了。

下面开始整合cache+redis  
1.在spring-mvc.xml中加入配置

<cache:annotation-driven cache-manager="cacheManager"/>
        
        <bean id="cacheManager" class="org.springframework.cache.support.SimpleCacheManager">
            <property name="caches">
                <set>
                    
                    <bean class="com.gcol.qy.core.annotation.RedisCache">
                        <property name="redisTemplate" ref="redisTemplate" />
                        <property name="name" value="myCache"/>
                    </bean>
                </set>
            </property>
        </bean>

几点说明：

1.com.gcol.qy.core.annotation.RedisCache 这个类是我们自己写的类 他实现了cache接口用于操作redis 如下：  
2.redisTemplate 配置在spring-redis.xml 中配置好的bean 这里不作展示,不会配置redisTemplate的小伙伴去自行百度  
3.`<property name="name" value="myCache"/>` myCache 后面使用@Cacheable会用到

package com.gcol.qy.core.annotation;
    
    import java.io.ByteArrayInputStream;
    import java.io.ByteArrayOutputStream;
    import java.io.IOException;
    import java.io.ObjectInputStream;
    import java.io.ObjectOutputStream;
    import org.springframework.cache.Cache;
    import org.springframework.cache.support.SimpleValueWrapper;
    import org.springframework.dao.DataAccessException;
    import org.springframework.data.redis.connection.RedisConnection;
    import org.springframework.data.redis.core.RedisCallback;
    import org.springframework.data.redis.core.RedisTemplate;
    
    /** * @Author: Xuhao * @Date: Created in 14:29 2018/7/30 */
    public class RedisCache implements Cache { 
    
        private RedisTemplate<String, Object> redisTemplate;
        private String name;
        public RedisTemplate<String, Object> getRedisTemplate() {
            return redisTemplate;
        }
    
        public void setRedisTemplate(RedisTemplate<String, Object> redisTemplate) {
            this.redisTemplate = redisTemplate;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        @Override
        public String getName() {
            // TODO Auto-generated method stub
            return this.name;
        }
    
        @Override
        public Object getNativeCache() {
            // TODO Auto-generated method stub
            return this.redisTemplate;
        }
    
        @Override
        public ValueWrapper get(Object key) {
            // TODO Auto-generated method stub
            System.out.println("get key");
            final String keyf = key.toString();
            Object object = null;
            object = redisTemplate.execute(new RedisCallback<Object>() {
                @Override
                public Object doInRedis(RedisConnection connection)
                        throws DataAccessException {
                    byte[] key = keyf.getBytes();
                    byte[] value = connection.get(key);
                    if (value == null) {
                        return null;
                    }
                    return toObject(value);
                }
            });
            return (object != null ? new SimpleValueWrapper(object) : null);
        }
    
        @Override
        public <T> T get(Object key, Class<T> type) {
            return null;
        }
    
        @Override
        public void put(Object key, Object value) {
            // TODO Auto-generated method stub
            System.out.println("put key");
            final String keyf = key.toString();
            final Object valuef = value;
            final long liveTime = 86400;
            redisTemplate.execute(new RedisCallback<Long>() {
                @Override
                public Long doInRedis(RedisConnection connection)
                        throws DataAccessException {
                    byte[] keyb = keyf.getBytes();
                    byte[] valueb = toByteArray(valuef);
                    connection.set(keyb, valueb);
                    if (liveTime > 0) {
                        connection.expire(keyb, liveTime);
                    }
                    return 1L;
                }
            });
        }
    
        private byte[] toByteArray(Object obj) {
            byte[] bytes = null;
            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            try {
                ObjectOutputStream oos = new ObjectOutputStream(bos);
                oos.writeObject(obj);
                oos.flush();
                bytes = bos.toByteArray();
                oos.close();
                bos.close();
            }catch (IOException ex) {
                ex.printStackTrace();
            }
            return bytes;
        }
    
        private Object toObject(byte[] bytes) {
            Object obj = null;
            try {
                ByteArrayInputStream bis = new ByteArrayInputStream(bytes);
                ObjectInputStream ois = new ObjectInputStream(bis);
                obj = ois.readObject();
                ois.close();
                bis.close();
            } catch (IOException ex) {
                ex.printStackTrace();
            } catch (ClassNotFoundException ex) {
                ex.printStackTrace();
            }
            return obj;
        }
    
        @Override
        public void evict(Object key) {
            // TODO Auto-generated method stub
            System.out.println("del key");
            final String keyf = key.toString();
            redisTemplate.execute(new RedisCallback<Long>() {
                @Override
                public Long doInRedis(RedisConnection connection)
                        throws DataAccessException {
                    return connection.del(keyf.getBytes());
                }
            });
        }
    
        @Override
        public void clear() {
            // TODO Auto-generated method stub
            System.out.println("clear key");
            redisTemplate.execute(new RedisCallback<String>() {
                @Override
                public String doInRedis(RedisConnection connection)
                        throws DataAccessException {
                    connection.flushDb();
                    return "ok";
                }
            });
        }
    }

测试Dao

@Override
    @Cacheable(value = "myCache",key = "#openid")
    public List<Object> findListCDKeyByOpenid(String openid) {
        Session session = super.getSession();
        String sql ="SELECT " +
                        "pri.cd_key as cdKey, " +
                        "war.award_name as awardName," +
                        "war.award_content as awardContent " +
                    " FROM wechat_test_prizes pri " +
                    " JOIN " +
                    " wechat_test_awards war on(pri.award_id=war.id)" +
                    " WHERE " +
                        "pri.id in (" +
                            " SELECT prize_id FROM wechat_user_lottery_record" +
                            " WHERE openid =:openid and Activity_code = 'CHILDFQ_QUIZ'" +
                        ");";
        SQLQuery sqlQuery = session.createSQLQuery(sql);
        sqlQuery.setParameter("openid",openid);
        sqlQuery.setResultTransformer(Transformers.ALIAS_TO_ENTITY_MAP);
    
        return sqlQuery.list();
    }

第一次调用如下：  
![这里写图片描述][70]  
第二次如下：没执行sql 直接从redis里获取的  
![这里写图片描述][70 1]

[70]: /images/20220518/1f53f0d7c29b4b11819c4c28e42d8e44.png
[70 1]: /images/20220518/d8732f990d8b4abd920b552685f0cc04.png