redis Application Development

redis definition:

What 1.redis that?
redis is a key-value high-performance database, the stored value type comprising support string, list, set, zset and the hash, and support the push / pop add / remove and intersected union and difference operations.
2.redis features:

• Data is cached in memory, will periodically update the data written to disk or to modify the operating log file additional written.
• Deployed in a cluster, the master server for external services, support master-slave synchronization, data can be from any number of servers to sync from the master server supports cascading architecture.
• Achieve a publish / subscribe mechanism, sub-channel data is stored (in a different channel), the premise consumption data to a subscription channel.
• edis worth is not limited to the type of string, but the string of further support:
  
  3.redis architecture:
  
• No interaction between the center-based architecture, the node
• The position of the master node hash algorithm key values ​​and their mappings stored, each node maintains the mapping between the key and the server
• client can initiate a request to any node, it does not matter from the master, if the server is client nodes are looking for, it will respond, if not, it will only redirect client
• If between the client request and redirects the request, topology changes, the next request will be redirected to redirect again, until you find the right server
• But fusionInsight HD in redis clusters only support a master-slave mode

4. Scenario:
Get the latest news
leaderboard application
counter application
in accordance with: high-performance low-latency access to rich data structures to support persistence
5. Implement product recommendation system:
program:
the introduction of redis, reduce the number of read data from the database and file system ;
cache the results to redis, realization and read and take; relative to the HBase faster because HBase although the index still going to access the underlying file system
structure design:
because the stored data is unstructured, there is no time to read table class information
using hash access structure:
<Key, value> ->
<the userid, name, Xiaoming>
<the userid, Age, 18 is>

MapReduce task timing to the user information imported from redis HBase; and
get data in the start redis obtain, if not then go get HBase, and sync to redis

redis cluster operations

note:

• Introducing an amount of data is limited to a memory configuration and redis cluster instance, the total capacity of the number of instances redis * = the memory size of a single instance;
• And should be split data to a plurality of the key, so that the data load balancing.

API the Java:
1. cluster initialization
using jedis

public RedisTest() {
//实例化一个集群的集合
        Set<HostAndPort> hosts = new HashSet<HostAndPort>();
        //通过ip地址和端口号获取到集群
        hosts.add(new HostAndPort(”node01“, 6379));
        int timeout = 5000;
        client = new JedisCluster(hosts, timeout);
    }

String type stores:

public void testString() {
        String key = "sid-user01";

        // 设置指定key值,过期时间，sessionid
        client.setex(key, 5, "A0BC9869FBC92933255A37A1D21167B2");
        //获取指定的key值
        String sessionId = client.get(key);
        LOGGER.info("User " + key + ", session id: " + sessionId);
        try {
            Thread.sleep(10000);//进程休息
        } catch (InterruptedException e) {
            LOGGER.warn("InterruptedException");
        }

        sessionId = client.get(key);
        LOGGER.info("User " + key + ", session id: " + sessionId);

        key = "message";
        //追加key,value

        client.set(key, "hello");
        String value = client.get(key);
        LOGGER.info("Value: " + value);

        client.append(key, " world");
        value = client.get(key);
        LOGGER.info("After append, value: " + value);

        client.del(key);
    }

hash storage type:

public void testHash() {
        String key = "userinfo-001";

        // 以key,field,value的形式存入数据
        client.hset(key, "id", "J001");
        client.hset(key, "name", "John");
        client.hset(key, "gender", "male");
        client.hset(key, "age", "35");
        client.hset(key, "salary", "1000000");

        // get方式获取 一个字段的值
        String id = client.hget(key, "id");
        String name = client.hget(key, "name");
        LOGGER.info("User " + id + "'s name is " + name);

        Map<String, String> user = client.hgetAll(key);
        LOGGER.info(user);
        client.del(key);

        key = "userinfo-002";
        Map<String, String> user2 = new HashMap<String, String>();
        user2.put("id", "L002");
        user2.put("name", "Lucy");
        user2.put("gender", "female");
        user2.put("age", "25");
        user2.put("salary", "200000");
        client.hmset(key, user2);
        //追加
        client.hincrBy(key, "salary", 50000);
        id = client.hget(key, "id");
        String salary = client.hget(key, "salary");
        LOGGER.info("User " + id + "'s salary is " + salary);

        // like Map.keySet()
        Set<String> keys = client.hkeys(key);
        LOGGER.info("all fields: " + keys);
        // like Map.values()
        List<String> values = client.hvals(key);
        LOGGER.info("all values: " + values);

        // 获取多个字段的值
        values = client.hmget(key, "id", "name");
        LOGGER.info("partial field values: " + values);

        // 判断key值是否已经存在
        boolean exist = client.hexists(key, "gender");
        LOGGER.info("Exist field gender? " + exist);

        // 删除key
        client.hdel(key, "age");
        keys = client.hkeys(key);
        LOGGER.info("after del field age, rest fields: " + keys);

        client.del(key);
    }