0 basic concepts

Jedis: A java tool for operating redis database.
       * Steps to use:
           1. Download the jar package of jedis
           2. Use
               //1. Get the connection
       Jedis jedis = new Jedis("localhost",6379);
            //2. Operate
            jedis .set("username","zhangsan");
       //3. Close the connection
       jedis.close();

1. Jedis operates various data structures in redis

1.1 String type string

set
				
get

//1. 获取连接
		        
Jedis jedis = new Jedis();//如果使用空参构造，默认值 "localhost",6379端口
		        
//2. 操作
		        
//存储
		        
jedis.set("username","zhangsan");
		        
//获取
		        
String username = jedis.get("username");
		        
System.out.println(username);
		
		        
//可以使用setex()方法存储可以指定过期时间的 key value
		        
jedis.setex("activecode",20,"hehe");//将activecode：hehe键值对存入redis，并且20秒后自动删除该键值对
		
		        
//3. 关闭连接
		        
jedis.close();

1.2 Hash type hash: map format

                hset
                hget
                hgetAll
                //1. 获取连接
                Jedis jedis = new Jedis();//如果使用空参构造，默认值 "localhost",6379端口
                //2. 操作
                // 存储hash
                jedis.hset("user","name","lisi");
                jedis.hset("user","age","23");
                jedis.hset("user","gender","female");
        
                // 获取hash
                String name = jedis.hget("user", "name");
                System.out.println(name);
        
        
                // 获取hash的所有map中的数据
                Map<String, String> user = jedis.hgetAll("user");
        
                // keyset
                Set<String> keySet = user.keySet();
                for (String key : keySet) {
                    //获取value
                    String value = user.get(key);
                    System.out.println(key + ":" + value);
                }
        
                //3. 关闭连接
                jedis.close();

1.3 list type list: linkedlist format. Support for repeating elements

                lpush / rpush
				lpop / rpop
				lrange start end : 范围获取
				
				 //1. 获取连接
		        Jedis jedis = new Jedis();//如果使用空参构造，默认值 "localhost",6379端口
		        //2. 操作
		        // list 存储
		        jedis.lpush("mylist","a","b","c");//从左边存
		        jedis.rpush("mylist","a","b","c");//从右边存
		
		        // list 范围获取
		        List<String> mylist = jedis.lrange("mylist", 0, -1);
		        System.out.println(mylist);
		        
		        // list 弹出
		        String element1 = jedis.lpop("mylist");//c
		        System.out.println(element1);
		
		        String element2 = jedis.rpop("mylist");//c
		        System.out.println(element2);
		
		        // list 范围获取
		        List<String> mylist2 = jedis.lrange("mylist", 0, -1);
		        System.out.println(mylist2);
		
		        //3. 关闭连接
		        jedis.close();

1.4 Collection type set: Duplicate elements are not allowed

                sadd
				smembers:获取所有元素

				//1. 获取连接
		        Jedis jedis = new Jedis();//如果使用空参构造，默认值 "localhost",6379端口
		        //2. 操作
		
		
		        // set 存储
		        jedis.sadd("myset","java","php","c++");
		
		        // set 获取
		        Set<String> myset = jedis.smembers("myset");
		        System.out.println(myset);
		
		        //3. 关闭连接
		        jedis.close();

1.5 Ordered collection type sortedset: duplicate elements are not allowed, and the elements are in order

                zadd
				zrange

				//1. 获取连接
		        Jedis jedis = new Jedis();//如果使用空参构造，默认值 "localhost",6379端口
		        //2. 操作
		        // sortedset 存储
		        jedis.zadd("mysortedset",3,"亚瑟");
		        jedis.zadd("mysortedset",30,"后裔");
		        jedis.zadd("mysortedset",55,"孙悟空");
		
		        // sortedset 获取
		        Set<String> mysortedset = jedis.zrange("mysortedset", 0, -1);
		
		        System.out.println(mysortedset);
		
		
		        //3. 关闭连接
		        jedis.close();

2.jedis connection pool: JedisPool

* use:

               1. Create a JedisPool connection pool object
               2. Call the method getResource() method to obtain the Jedis connection
                   //0. Create a configuration object
           JedisPoolConfig config = new JedisPoolConfig();
           config.setMaxTotal(50);
           config.setMaxIdle(10);

           // 1. Create a Jedis connection pool object
           JedisPool jedisPool = new JedisPool(config,"localhost",6379);

           //2. Get a connection
           Jedis jedis = jedisPool.getResource();
           //3. Use
           jedis.set("hehe", "heihei");


           //4. Close and return to the connection pool
           jedis.close();

* Connection pool tool class

public class JedisPoolUtils {

	private static JedisPool jedisPool;
				
	static{
		//读取配置文件
		InputStream is = JedisPoolUtils.class.getClassLoader().getResourceAsStream("jedis.properties");
		//创建Properties对象
		Properties pro = new Properties();
		//关联文件
		try {
		     pro.load(is);
			} catch (IOException e) {
			  e.printStackTrace();
			}
		//获取数据，设置到JedisPoolConfig中
		JedisPoolConfig config = new JedisPoolConfig();
				        
        config.setMaxTotal(Integer.parseInt(pro.getProperty("maxTotal")));
		config.setMaxIdle(Integer.parseInt(pro.getProperty("maxIdle")));
				
		//初始化JedisPool
		jedisPool = new JedisPool(config,pro.getProperty("host"),Integer.parseInt(pro.getProperty("port")));
									
				    }
				
				
				    /**
				     * 获取连接方法
				     */
				    public static Jedis getJedis(){
				        return jedisPool.getResource();
				    }
				}

3. Case

Case requirements:
1. Provide an index.html page with a drop-down list of provinces
2. When the page is loaded, send an ajax request to load all provinces

   * Note: Use redis to cache some data that does not change frequently.
       * Once the data in the database changes, the cache needs to be updated.
           * To perform addition, deletion, and modification operations on database tables, the redis cache data needs to be stored again
           * In the addition, deletion, and modification methods corresponding to the service, the redis data is deleted.

Beginner Jedis