Redis入门

数据库多样性

类型：

访问模式决定采用哪种数据库，同步的问题

关系型：Oracle MySQL ...，实时事务处理
文档性：MongoDB，适合高聚合的数据结构
KV型：Redis，高速存放和查找，中间缓存
全文搜索：ElasticSearch Solor，输入关键词，不仅仅是String.contains，分词...
分布式：HBASE 大数据Hadoop HDFS

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Map<K, V>
K key
V value

map.put(k, v)
map.get(k)

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设置键值对
set k v
取值
get k
一次多个键,multiple
mset k1 v1 k2 v2 ...
mget k1 k2 ...

调试命令：
查找符合pattern的所有key，*表示任意字符串
keys pattern

指定有效期
TTL； time to live

设置键值对并指定有效期，单位秒
setex k ex v

将指定键的值+1
incr k
将指定键的值-1
decr k

删除键值对
del k

　　pom.xml

        <dependency>
            <groupId>redis.clients</groupId>
            <artifactId>jedis</artifactId>
            <version>2.9.0</version>
            <type>jar</type>
            <scope>compile</scope>
        </dependency>

　　ArticleService.java

package redistest;

import java.util.List;

import redis.clients.jedis.Jedis;

public class ArticleService {

    private Jedis jedis = new Jedis("localhost");
    
    public void add(long id, String title) {
        String key = titleKey(id); // article:1:title
        jedis.set(key, title);
    }

    private String titleKey(long id) {
        return "article:" + id + ":title";
    }
    
    public void upVote(long id) {
//        incr article:2:upvotes        
        jedis.incr(upvotesKey(id));
    }

    private String upvotesKey(long id) {
        return "article:" + id + ":upvotes";
    }

    public void downVote(long id) {
//        incr article:2:downvotes        
        jedis.incr(downvotesKey(id));
    }

    private String downvotesKey(long id) {
        return "article:" + id + ":downvotes";
    }

    public String info(long id) {
        List<String> values = jedis.mget(titleKey(id), 
                upvotesKey(id), downvotesKey(id));
        String title = values.get(0);
        String upvotes = values.get(1);
        String downvotes = values.get(2);
        
        return title + "#" + id + "[" + upvotes + ", " + downvotes + "]";
    }
}

ArticleServiceTest.java

package redistest;

public class ArticleServiceTest {
    public static void main(String[] args) {
        ArticleService service = new ArticleService();
        service.add(1L, "标题1");
        service.add(2L, "标题2");
        service.add(3L, "标题3");
        
//        for (int i = 0; i < 100; i++) {
//            service.upVote(2L);
//        }
        
        service.downVote(3L);
        
        System.out.println(service.info(1));
        System.out.println(service.info(2));
        System.out.println(service.info(3));
    }
}