redis緩存的簡(jiǎn)單操作（get、put）

<!-- java訪問(wèn)redis的jar包jedis -->
<dependency>
 <groupId>redis.clients</groupId>
 <artifactId>jedis</artifactId>
 <version>2.7.3</version>
</dependency>
<!-- protostuff序列化依賴(lài) -->
<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連接池
 private final JedisPool jedisPool;//根據(jù)對(duì)象的字節(jié)碼文件，生成空對(duì)象
 private RuntimeSchema<Object> schema = RuntimeSchema.createFrom(Object.class); //Object.class：獲取對(duì)象的字節(jié)碼
 
 public RedisDao(String ip, int port){
  jedisPool = new JedisPool(ip, port);
 }

//將對(duì)象緩存到redis
 public String putObject(Object obj){
  //緩存邏輯:Object --> 序列化 --> byte[] --> 緩存到redis
  try {
   Jedis jedis = jedisPool.getResource(); //獲取redis的連接對(duì)象，相當(dāng)于JDBC的connection
   try{
    String key = "Object:"+obj.getId();
    //進(jìn)行序列化
    byte[] bytes = ProtostuffIOUtil.toByteArray(seckill, schema, 
      LinkedBuffer.allocate(LinkedBuffer.DEFAULT_BUFFER_SIZE)); //如果對(duì)象過(guò)大，會(huì)進(jìn)行緩沖
    //開(kāi)始緩存
    int timeout = 60*60; //設(shè)置超時(shí)時(shí)間 一小時(shí),通過(guò)超時(shí)維護(hù)一致性
    String result = jedis.setex(key.getBytes(), timeout, bytes);
    return result;
   }finally{
    jedis.close();
   }
  } catch (Exception e) {
   e.printStack();
  }
  return null;
 }

 //從redis緩存中查詢(xún)
 public Object getObject(long id){
  //redis操作邏輯
  try {
   Jedis jedis = jedisPool.getResource(); //緩存連接對(duì)象，相當(dāng)于數(shù)據(jù)庫(kù)連接對(duì)象connection
   try {
    String key = "Object:"+id;
    //實(shí)體對(duì)象并沒(méi)有實(shí)現(xiàn)內(nèi)部序列化操作
    //緩存邏輯：getByte[] --> 反序列化 --> Object
    byte[] bytes = jedis.get(key.getBytes()); //從jedis中獲取目標(biāo)對(duì)象的序列化對(duì)象數(shù)組
    if(bytes != null){
     //反序列化邏輯
     Object obj = schema.newMessage(); //通過(guò)schema生成一個(gè)新的空對(duì)象
     ProtostuffIOUtil.mergeFrom(bytes, obj, schema); //進(jìn)行反序列化操作
     return obj;
    }
    
   } finally {
    jedis.close();
   }
    
  } catch (Exception e) {
　　　　　　　　e.printStack();
  }
  return null;
 }

get form redis_cache    //首先查詢(xún)r(jià)edis
if null       //如果沒(méi)有
 get from db     //再?gòu)臄?shù)據(jù)庫(kù)db查詢(xún)
 if null      //如果仍然沒(méi)有
  return null    //那么返回空
 else       //否則
  put into redis_cache  //現(xiàn)將數(shù)據(jù)放入redis
  return obj    //再放回?cái)?shù)據(jù)
else        //如果從redis中查詢(xún)到了
 return obj     //那么直接返回?cái)?shù)據(jù)