五、Java内存数据库实践之深入浅出Redis - Jedis分布式（Sharding/Sharded)

一、Jedis分布式（Sharding/shared 一致性哈希）

    我们知道Memcached是完全基于分布式的集群，而Redis是Master-Slave的模式，如果想把Redis做成集群模式，其实无外乎就是多做几套Master-Slave，每套Master-Slave完成各自的容灾处理，通过Client工具，完成一致性哈希。（PS:Memcached是在Server端完成Sharding，Redis只能依靠各个Client做Sharding。但比较开心的是从3.0的正式版开始，Redis也会像Memache一样开始支持Server端的集群）

    shared一致性哈希采用以下方案：

1. Redis服务器节点划分：将每台服务器节点采用hash算法划分为160个虚拟节点(可以配置划分权重)

2. 将划分虚拟节点采用TreeMap存储

3. 对每个Redis服务器的物理连接采用LinkedHashMap存储

4. 对Key or KeyTag 采用同样的hash算法，然后从TreeMap获取大于等于键hash值得节点，取最邻近节点存储；当key的hash值大于虚拟节点hash值得最大值时，存入第一个虚拟节点

    使用上一篇中的JedisPoolConfig，新增两个Redis的IP，此处假设为redis1.ip和redis2.ip。需要添加的代码就是新增两个JedisShardInfo实例，并将其放进List中：

bundle.getString("redis1.ip"), Integer.valueOf(bundle                       .getString("redis.port")));
JedisShardInfo jedisShardInfo2 = new JedisShardInfo(
bundle.getString("redis2.ip"), Integer.valueOf(bundle                       .getString("redis.port")));
List<JedisShardInfo> list = new LinkedList<JedisShardInfo>();
list.add(jedisShardInfo1);
list.add(jedisShardInfo2);

 初始化ShardedJedisPool代替JedisPool：

ShardedJedisPool pool = new ShardedJedisPool(config, list);

 改由ShardedJedis，获取Jedis对象：

// 从池中获取一个Jedis对象
ShardedJedis jedis = pool.getResource();
String keys = "name";
String value = "snowolf";
// 删数据
jedis.del(keys);
// 存数据
jedis.set(keys, value);
// 取数据
String v = jedis.get(keys);
System.out.println(v);
// 释放对象池
pool.returnResource(jedis);

通过以上方式，向redis进行set操作的key-value，会通过hash而均匀的分配到pool里的redis机器中。

三、使用Shading和非Shading的示例：

package com.chuanliu.platform.activity.cache;

import java.util.ArrayList;
import java.util.List;

import org.junit.Before;
import org.junit.Test;

import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.JedisPoolConfig;
import redis.clients.jedis.JedisShardInfo;
import redis.clients.jedis.ShardedJedis;
import redis.clients.jedis.ShardedJedisPool;

/**
 * The unit test used to simulate the distribution(master/slave) 
 * of Redis
 * 
 * @author Josh Wang(Sheng)
 *
 * @email  [email protected]
 */
public class TestCombination {

	/**
	* 非切片客户端链接
	*/
	private Jedis jedis;
	
	/**
	* 非切片链接池
	*/
	private JedisPool jedisPool;
	
	/**
	* 切片客户端链接
	*/
	private ShardedJedis shardedJedis;
	
	/**
	* 切片链接池
	*/
	private ShardedJedisPool shardedJedisPool;
	private String ip = "172.16.205.186";
	
	/**
	* 构造函数
	*/
	@Before
	public void init() {
		initialPool();
		initialShardedPool();
		shardedJedis = shardedJedisPool.getResource();
		jedis = jedisPool.getResource();
	}
	
	private void initialPool() {
		// 池基本配置
		JedisPoolConfig config = new JedisPoolConfig();
		config.setMaxActive(20);
		config.setMaxIdle(5);
		config.setMaxWait(1000l);
		config.setTestOnBorrow(false);
		jedisPool = new JedisPool(config, ip, 6379);
	}
	
	/**
	* 初始化切片池
	*/
	private void initialShardedPool() {
		// 池基本配置
		JedisPoolConfig config = new JedisPoolConfig();
		config.setMaxActive(20);
		config.setMaxIdle(5);
		config.setMaxWait(1000l);
		config.setTestOnBorrow(false);
		// slave链接
		List<JedisShardInfo> shards = new ArrayList<JedisShardInfo>();
		shards.add(new JedisShardInfo(ip, 6379, "master"));
		// 构造池
		shardedJedisPool = new ShardedJedisPool(config, shards);
	}
	
	@Test
	public void show() {
		// key检测
		testKey();
		
		// string检测
		testString();
		
		// list检测
		testList();
		
		// set检测
		testSet();
		
		// sortedSet检测
		testSortedSet();
		
		// hash检测
		testHash();
		
		shardedJedisPool.returnResource(shardedJedis);
	}
	
	private void testKey() {
		System.out.println("=============key==========================");
		// 清空数据
		System.out.println(jedis.flushDB());
		System.out.println(jedis.echo("foo"));
		// 判断key否存在
		System.out.println(shardedJedis.exists("foo"));
		shardedJedis.set("key", "values");
		System.out.println(shardedJedis.exists("key"));
	}
	
	private void testString() {
		System.out.println("=============String==========================");
		// 清空数据
		System.out.println(jedis.flushDB());
		
		// 存储数据
		shardedJedis.set("foo", "bar");
		System.out.println(shardedJedis.get("foo"));
		
		// 若key不存在，则存储
		shardedJedis.setnx("foo", "foo not exits");
		System.out.println(shardedJedis.get("foo"));
		
		// 覆盖数据
		shardedJedis.set("foo", "foo update");
		System.out.println(shardedJedis.get("foo"));
		
		// 追加数据
		shardedJedis.append("foo", " hello, world");
		System.out.println(shardedJedis.get("foo"));
		
		// 设置key的有效期，并存储数据
		shardedJedis.setex("foo", 2, "foo not exits");
		System.out.println(shardedJedis.get("foo"));
		try {
		Thread.sleep(3000);
		} catch (InterruptedException e) {
		}
		System.out.println(shardedJedis.get("foo"));
		
		// 获取并更改数据
		shardedJedis.set("foo", "foo update");
		System.out.println(shardedJedis.getSet("foo", "foo modify"));
		
		// 截取value的值
		System.out.println(shardedJedis.getrange("foo", 1, 3));
		System.out.println(jedis.mset("mset1", "mvalue1", "mset2", "mvalue2",
		"mset3", "mvalue3", "mset4", "mvalue4"));
		System.out.println(jedis.mget("mset1", "mset2", "mset3", "mset4"));
		System.out.println(jedis.del(new String[] { "foo", "foo1", "foo3" }));
	}
	
	private void testList() {
	System.out.println("=============list==========================");
	// 清空数据
		System.out.println(jedis.flushDB());
		// 添加数据
		shardedJedis.lpush("lists", "vector");
		shardedJedis.lpush("lists", "ArrayList");
		shardedJedis.lpush("lists", "LinkedList");
		// 数组长度
		System.out.println(shardedJedis.llen("lists"));
		// 排序
	//	      System.out.println(shardedJedis.sort("lists"));
		// 字串
		System.out.println(shardedJedis.lrange("lists", 0, 3));
		// 修改列表中单个值
		shardedJedis.lset("lists", 0, "hello list!");
		// 获取列表指定下标的值
		System.out.println(shardedJedis.lindex("lists", 1));
		// 删除列表指定下标的值
		System.out.println(shardedJedis.lrem("lists", 1, "vector"));
		// 删除区间以外的数据
		System.out.println(shardedJedis.ltrim("lists", 0, 1));
		// 列表出栈
		System.out.println(shardedJedis.lpop("lists"));
		// 整个列表值
		System.out.println(shardedJedis.lrange("lists", 0, -1));
		}
		private void testSet() {
		System.out.println("=============set==========================");
		// 清空数据
		System.out.println(jedis.flushDB());
		// 添加数据
		shardedJedis.sadd("sets", "HashSet");
		shardedJedis.sadd("sets", "SortedSet");
		shardedJedis.sadd("sets", "TreeSet");
		// 判断value是否在列表中
		System.out.println(shardedJedis.sismember("sets", "TreeSet"));
		;
		// 整个列表值
		System.out.println(shardedJedis.smembers("sets"));
		// 删除指定元素
		System.out.println(shardedJedis.srem("sets", "SortedSet"));
		// 出栈
		System.out.println(shardedJedis.spop("sets"));
		System.out.println(shardedJedis.smembers("sets"));
		//
		shardedJedis.sadd("sets1", "HashSet1");
		shardedJedis.sadd("sets1", "SortedSet1");
		shardedJedis.sadd("sets1", "TreeSet");
		shardedJedis.sadd("sets2", "HashSet2");
		shardedJedis.sadd("sets2", "SortedSet1");
		shardedJedis.sadd("sets2", "TreeSet1");
		// 交集
		System.out.println(jedis.sinter("sets1", "sets2"));
		// 并集
		System.out.println(jedis.sunion("sets1", "sets2"));
		// 差集
		System.out.println(jedis.sdiff("sets1", "sets2"));
	}
		
	private void testSortedSet() {
		System.out.println("=============zset==========================");
		// 清空数据
		System.out.println(jedis.flushDB());
		// 添加数据
		shardedJedis.zadd("zset", 10.1, "hello");
		shardedJedis.zadd("zset", 10.0, ":");
		shardedJedis.zadd("zset", 9.0, "zset");
		shardedJedis.zadd("zset", 11.0, "zset!");
		// 元素个数
		System.out.println(shardedJedis.zcard("zset"));
		// 元素下标
		System.out.println(shardedJedis.zscore("zset", "zset"));
		// 集合子集
		System.out.println(shardedJedis.zrange("zset", 0, -1));
		// 删除元素
		System.out.println(shardedJedis.zrem("zset", "zset!"));
		System.out.println(shardedJedis.zcount("zset", 9.5, 10.5));
		// 整个集合值
		System.out.println(shardedJedis.zrange("zset", 0, -1));
	}
	
	private void testHash() {
		System.out.println("=============hash==========================");
		
		// 清空数据
		System.out.println(jedis.flushDB());
		
		// 添加数据
		shardedJedis.hset("hashs", "entryKey", "entryValue");
		shardedJedis.hset("hashs", "entryKey1", "entryValue1");
		shardedJedis.hset("hashs", "entryKey2", "entryValue2");
		
		// 判断某个值是否存在
		System.out.println(shardedJedis.hexists("hashs", "entryKey"));
		
		// 获取指定的值
		System.out.println(shardedJedis.hget("hashs", "entryKey"));
		
		// 批量获取指定的值
		System.out
		.println(shardedJedis.hmget("hashs", "entryKey", "entryKey1"));
		
		// 删除指定的值
		System.out.println(shardedJedis.hdel("hashs", "entryKey"));
		
		// 为key中的域 field 的值加上增量 increment
		System.out.println(shardedJedis.hincrBy("hashs", "entryKey", 123l));
		
		// 获取所有的keys
		System.out.println(shardedJedis.hkeys("hashs"));
		
		// 获取所有的values
		System.out.println(shardedJedis.hvals("hashs"));
	}
}