redis分散式演算法原理:

本例中我們打開了兩個redis服務，一個6379埠，一個6380埠，那麼我們儲存資料的時候是怎麼分配的了，object1經過hsah到了他的位置上，存放到cacheA節點上，其它如object2，object3，object4也到了各自的位置，每個如cacheA的節點其實就是一個redis服務，順時針分配object1分配到了cacheA上，但是這樣有一個問題，那就是分配不均勻，所以就有了cacheA，cacheB，cacheC的虛擬節點（圖中沒有示例），每個虛擬節點的資料映射回自己的主節點，那麼資料的分配最大程度上就分配均勻了

1.redis分散式連線池

public
 
 class RedisShardedPool {
    private static ShardedJedisPool pool;//Sharded Jedis連線池
    private static Integer maxTotal =  Integer.valueOf(PropertiesUtil.getProperty("redis.max.total","20"));   //最大連線數
    private static Integer maxIdle = Integer.valueOf(PropertiesUtil.getProperty("redis.max.idle","10"));//
 
在jedispool中最大的idle狀態（空閒的）的jedis例項的個數
    private static Integer minIdle = Integer.valueOf(PropertiesUtil.getProperty("redis.min.idle","2"));//在jedispool中最小的idle狀態（空閒的）的jedis例項的個數
    private static Boolean testOnBorrow =  Boolean.valueOf(PropertiesUtil.getProperty("redis.test.borrow","true"));//在borrow一個Jedis例項的時候，是否要進行驗證操作，如果賦值true，那麼得到的jedis例項肯定是可用的
 

    private static Boolean testOnReturn =  Boolean.valueOf(PropertiesUtil.getProperty("redis.test.return","true"));//在borrow一個Jedis例項的時候，是否要進行驗證操作，如果賦值true，則放回jedispool的jedis例項肯定是可用的

    private static String redis1Ip = PropertiesUtil.getProperty("redis1.ip");
    private static Integer redis1Port = Integer.valueOf(PropertiesUtil.getProperty("redis1.port"));

    private static String redis2Ip = PropertiesUtil.getProperty("redis2.ip");
    private static Integer redis2Port = Integer.valueOf(PropertiesUtil.getProperty("redis2.port"));

    private static void initPool(){
        JedisPoolConfig config = new JedisPoolConfig();
        config.setMaxTotal(maxTotal);
        config.setMaxIdle(maxIdle);
        config.setMinIdle(minIdle);
        config.setTestOnBorrow(testOnBorrow);
        config.setTestOnReturn(testOnReturn);

        config.setBlockWhenExhausted(true);//連線耗盡的時候是否阻塞，true：阻塞，false:丟擲異常

        //pool = new JedisPool(config,redisIp,redisPort,1000*2);

        JedisShardInfo info1 = new JedisShardInfo(redis1Ip,redis1Port,1000*2);
        //info1.setPassword("ddddd");//如果有密碼的話
        JedisShardInfo info2 = new JedisShardInfo(redis2Ip,redis2Port,1000*2);

        List<JedisShardInfo> jedisShardInfoList = new ArrayList<JedisShardInfo>(2);
        jedisShardInfoList.add(info1);
        jedisShardInfoList.add(info2);
        pool = new ShardedJedisPool(config,jedisShardInfoList, Hashing.MURMUR_HASH, Sharded.DEFAULT_KEY_TAG_PATTERN);
    }

    static {
        initPool();
    }

/*    public static Jedis getJedis(){
        return pool.getResource();
    }*/

    public static ShardedJedis getJedis(){
        return pool.getResource();
    }

    public static void returnBrokenResource(ShardedJedis jedis){
        pool.returnBrokenResource(jedis);
    }

    public static void returnResource(ShardedJedis jedis){
        pool.returnResource(jedis);
    }

    public static void main (String[] args){
        ShardedJedis jedis = pool.getResource();

        for (int i=0;i<10;i++){
            jedis.set("key"+i,"value"+i);
        }

        //jedis.set("geelykey","geelyvalue");
        returnResource(jedis);
     //   pool.destroy();//臨時呼叫
        System.out.println("program is end");
    }




}

2.寫一個工具類封裝redis分散式操作方法

public class RedisShardedPoolUtil {
    /*設定key的有效期，單位是秒*/
    public static Long expire(String key,int exTime){
        ShardedJedis jedis = null;
        Long result = null;

        try {
            jedis = RedisShardedPool.getJedis();
            result = jedis.expire(key,exTime);
        } catch (Exception e) {
            log.error("expire key:{} exTime:{}  error",key,exTime,e);
            RedisShardedPool.returnBrokenResource(jedis);
            return result;
        }
        RedisShardedPool.returnResource(jedis);
        return  result;

    }


    //exTime的單位是秒
    public static String setEx(String key,String value,int exTime){
        ShardedJedis jedis = null;
        String result = null;

        try {
            jedis = RedisShardedPool.getJedis();
            result = jedis.setex(key,exTime,value);
        } catch (Exception e) {
            log.error("setex key:{} exTime:{} value:{} error",key,exTime,value,e);
            RedisShardedPool.returnBrokenResource(jedis);
            return result;
        }
        RedisShardedPool.returnResource(jedis);
        return  result;

    }

    public static String set(String key,String value){
        ShardedJedis jedis = null;
        String result = null;

        try {
            jedis = RedisShardedPool.getJedis();
            result = jedis.set(key, value);
        } catch (Exception e) {
            log.error("set key:{} value:{} error",key,value,e);
            RedisShardedPool.returnBrokenResource(jedis);
            return result;
        }
        RedisShardedPool.returnResource(jedis);
        return  result;

    }

    public static String getSet(String key,String value){
        ShardedJedis jedis = null;
        String result = null;

        try {
            jedis = RedisShardedPool.getJedis();
            result = jedis.getSet(key, value);
        } catch (Exception e) {
            log.error("getSet key:{} value:{} error",key,value,e);
            RedisShardedPool.returnBrokenResource(jedis);
            return result;
        }
        RedisShardedPool.returnResource(jedis);
        return  result;

    }

    public static Long setnx(String key,String value){
        ShardedJedis jedis = null;
        Long result = null;

        try {
            jedis = RedisShardedPool.getJedis();
            result = jedis.setnx(key, value);
        } catch (Exception e) {
            log.error("set key:{} value:{} error",key,value,e);
            RedisShardedPool.returnBrokenResource(jedis);
            return result;
        }
        RedisShardedPool.returnResource(jedis);
        return  result;

    }

    public static String get(String key){
        ShardedJedis jedis = null;
        String result = null;

        try {
            jedis = RedisShardedPool.getJedis();
            result = jedis.get(key);
        } catch (Exception e) {
            log.error("get key:{} error",key,e);
            RedisShardedPool.returnBrokenResource(jedis);
            return result;
        }
        RedisShardedPool.returnResource(jedis);
        return  result;

    }

    public static Long del(String key){
        ShardedJedis jedis = null;
        Long result = null;

        try {
            jedis = RedisShardedPool.getJedis();
            result = jedis.del(key);
        } catch (Exception e) {
            log.error("del key:{} error",key,e);
            RedisShardedPool.returnBrokenResource(jedis);
            return result;
        }
        RedisShardedPool.returnResource(jedis);
        return  result;

    }

    public  static  void main (String[] args){
        Jedis jedis = RedisPool.getJedis();
        RedisPoolUtil.set("keyTest","value");
        String value = RedisPoolUtil.get("keyTest");
        RedisPoolUtil.setEx("kevex","valueex",60*10);
        RedisPoolUtil.expire("keyTest",60*20);
        RedisPoolUtil.del("keyTest");
        System.out.println("end");
    }





}