<!-- java访问redis的jar包jedis -->
<dependency>
 <groupId>redis.clients</groupId>
 <artifactId>jedis</artifactId>
 <version>2.7.3</version>
</dependency>
<!-- protostuff序列化依赖 -->
<dependency>
 <groupId>com.dyuproject.protostuff</groupId>
 <artifactId>protostuff-core</artifactId>
 <version>1.0.8</version>
</dependency>
<dependency>
 <groupId>com.dyuproject.protostuff</groupId>
 <artifactId>protostuff-runtime</artifactId>
 <version>1.0.8</version>
</dependency>

<!-- 注入redis dao -->
<bean id="redisDao" class="org.demo.dao.cache.RedisDao">
　　<constructor-arg index="0" value="localhost"></constructor-arg>
　　<constructor-arg index="1" value="6379"></constructor-arg>
</bean>

//redis连接池
 private final JedisPool jedisPool;//根据对象的字节码文件，生成空对象
 private RuntimeSchema<Object> schema = RuntimeSchema.createFrom(Object.class); //Object.class：获取对象的字节码
 
 public RedisDao(String ip, int port){
  jedisPool = new JedisPool(ip, port);
 }

//将对象缓存到redis
 public String putObject(Object obj){
  //缓存逻辑:Object --> 序列化 --> byte[] --> 缓存到redis
  try {
   Jedis jedis = jedisPool.getResource(); //获取redis的连接对象，相当于JDBC的connection
   try{
    String key = "Object:"+obj.getId();
    //进行序列化
    byte[] bytes = ProtostuffIOUtil.toByteArray(seckill, schema, 
      LinkedBuffer.allocate(LinkedBuffer.DEFAULT_BUFFER_SIZE)); //如果对象过大，会进行缓冲
    //开始缓存
    int timeout = 60*60; //设置超时时间 一小时,通过超时维护一致性
    String result = jedis.setex(key.getBytes(), timeout, bytes);
    return result;
   }finally{
    jedis.close();
   }
  } catch (Exception e) {
   e.printStack();
  }
  return null;
 }

 //从redis缓存中查询
 public Object getObject(long id){
  //redis操作逻辑
  try {
   Jedis jedis = jedisPool.getResource(); //缓存连接对象，相当于数据库连接对象connection
   try {
    String key = "Object:"+id;
    //实体对象并没有实现内部序列化操作
    //缓存逻辑：getByte[] --> 反序列化 --> Object
    byte[] bytes = jedis.get(key.getBytes()); //从jedis中获取目标对象的序列化对象数组
    if(bytes != null){
     //反序列化逻辑
     Object obj = schema.newMessage(); //通过schema生成一个新的空对象
     ProtostuffIOUtil.mergeFrom(bytes, obj, schema); //进行反序列化操作
     return obj;
    }
    
   } finally {
    jedis.close();
   }
    
  } catch (Exception e) {
　　　　　　　　e.printStack();
  }
  return null;
 }

get form redis_cache    //首先查询redis
if null       //如果没有
 get from db     //再从数据库db查询
 if null      //如果仍然没有
  return null    //那么返回空
 else       //否则
  put into redis_cache  //现将数据放入redis
  return obj    //再放回数据
else        //如果从redis中查询到了
 return obj     //那么直接返回数据