Jedis

Prerequisites

• The DCS Redis instance you want to access is in the Running state.
• An ECS has been created. For more information on how to create ECSs, see the Elastic Cloud Server User Guide.
• If the ECS runs the Linux OS, ensure that the Java compilation environment has been installed on the ECS.

Procedure

1. View the IP address/domain name and port number of the DCS Redis instance to be accessed.

   For details, see Viewing Details of a DCS Instance.

2. Log in to the ECS where you want to install Docker.
3. Use Maven to add the following dependency to the pom.xml file:

   <dependency>
       <groupId>redis.clients</groupId>
       <artifactId>jedis</artifactId>
       <version>4.1.1</version>
   </dependency>

4. Access the DCS instance by using Jedis.
   Obtain the source code of the Jedis client. Use either of the following two methods to access a DCS Redis instance through Jedis:

   • Single Jedis connection
   • Jedis pool

   Example code:

   1. Example of using Jedis to connect to a single-node, master/standby, or Proxy Cluster DCS Redis instance with a single connection

      // Creating a connection in password mode
       String host = "192.168.0.150"; 
       int port = 6379; 
       String pwd = "passwd"; 
        
       Jedis client = new Jedis(host, port); 
       client.auth(pwd);
       client.connect(); 
      // Run the set command
       String result = client.set("key-string", "Hello, Redis!"); 
      System.out.println( String.format("set instruction execution result:%s", result) );
      // Run the get command
       String value = client.get("key-string"); 
       System.out.println( String.format("get command result:%s", value) );
      
      // Creating a connection in password-free mode
       String host = "192.168.0.150"; 
       int port = 6379; 
        
       Jedis client = new Jedis(host, port); 
       client.connect(); 
      // Run the set command
       String result = client.set("key-string", "Hello, Redis!"); 
           System.out.println( String.format("set command result:%s", result) ); 
      // Run the get command
       String value = client.get("key-string"); 
       System.out.println( String.format("get command result:%s", value) );

      host indicates the example IP address/domain name of DCS instance and port indicates the port number of DCS instance. For details about how to obtain the IP address/domain name and port, see 1. Change the IP address and port as required. pwd indicates the password used for logging in to the chosen DCS Redis instance. This password is defined during DCS Redis instance creation.

   2. Example of using Jedis to connect to a single-node, master/standby, or Proxy Cluster DCS Redis instance with connection pooling

      // Generate configuration information of a Jedis pool
       String ip = "192.168.0.150"; 
       int port = 6379; 
       String pwd = "passwd"; 
       GenericObjectPoolConfig config = new GenericObjectPoolConfig(); 
       config.setTestOnBorrow(false); 
       config.setTestOnReturn(false); 
       config.testWhileIdle(true);
       config.setMaxTotal(100); 
       config.setMaxIdle(100); 
       config.setMaxWaitMillis(2000); 
      JedisPool pool = new JedisPool(config, ip, port, 100000, pwd);//Generate a Jedis pool when the application is being initialized
      // Get a Jedis connection from the Jedis pool when a service operation occurs
       Jedis client = pool.getResource(); 
       try { 
           // Run commands
           String result = client.set("key-string", "Hello, Redis!"); 
           System.out.println( String.format("set command result:%s", result) ); 
           String value = client.get("key-string"); 
           System.out.println( String.format("get command result:%s", value) ); 
       } catch (Exception e) { 
           // TODO: handle exception
       } finally { 
           // Return the Jedis connection to the Jedis connection pool after the client's request is processed
           if (null != client) { 
               pool.returnResource(client); 
           } 
       } // end of try block
       // Destroy the Jedis pool when the application is closed
       pool.destroy();
      
      // Configure the connection pool in the password-free mode
       String ip = "192.168.0.150"; 
       int port = 6379; 
       GenericObjectPoolConfig config = new GenericObjectPoolConfig(); 
       config.setTestOnBorrow(false); 
       config.setTestOnReturn(false); 
       config.testWhileIdle(true);
       config.setMaxTotal(100); 
       config.setMaxIdle(100); 
       config.setMaxWaitMillis(2000); 
       JedisPool pool = new JedisPool(config, ip, port, 100000);//Generate a JedisPool when the application is being initialized
      // Get a Jedis connection from the Jedis pool when a service operation occurs
       Jedis client = pool.getResource(); 
       try { 
           // Run commands
           String result = client.set("key-string", "Hello, Redis!"); 
           System.out.println( String.format("set command result:%s", result) ); 
           String value = client.get("key-string"); 
           System.out.println( String.format("get command result:%s", value) ); 
       } catch (Exception e) { 
           // TODO: handle exception
       } finally { 
           // Return the Jedis connection to the Jedis connection pool after the client's request is processed
           if (null != client) { 
               pool.returnResource(client); 
           } 
       } // end of try block
       // Destroy the Jedis pool when the application is closed
       pool.destroy();

      ip indicates the IP address/domain name of DCS instance and port indicates the port number of DCS instance. For details about how to obtain the IP address/domain name and port, see 1. Change the IP address and port as required. pwd indicates the password used for logging in to the chosen DCS Redis instance. This password is defined during DCS Redis instance creation.

      Automatic reconnection is supported if the testOnBorrow parameter of the connection pool is enabled. When the service tries to obtain a Redis connection from the connection pool, the connection pool checks connections. After detecting a normal connection, the connection pool provides the connection to the service at the cost of performance. If you require high performance, do not enable this parameter and configure the upper-layer application for it to handle exceptions and retries.

   3. Example code for connecting to Redis Cluster using a single connection
      • With a password

        //The following shows password-protected access.
        int port = 6379;
        String host = "192.168.144.37";
        //Create JedisCluster.
        Set<HostAndPort> nodes = new HashSet<HostAndPort>();
        nodes.add(new HostAndPort(host, port));
        JedisCluster cluster = new JedisCluster(nodes, 5000, 3000, 10, "password", new JedisPoolConfig());
        cluster.set("key", "value");
        System.out.println("Connected to RedisCluster:" + cluster.get("key"));
        cluster.close();

      • Without a password

        int port = 6379;
        String host = "192.168.144.37";
        //Create JedisCluster.
        Set<HostAndPort> nodes = new HashSet<HostAndPort>();
        nodes.add(new HostAndPort(host, port));
        JedisCluster cluster = new JedisCluster(nodes);
        cluster.set("key", "value");
        System.out.println("Connected to RedisCluster:" + cluster.get("key"));
        cluster.close();

      host indicates the example IP address/domain name of DCS instance and port indicates the port number of DCS instance. For details about how to obtain the IP address/domain name and port, see 1. Change the IP address and port as required. {password} indicates the password used to log in to the chosen DCS Redis instance. This password is defined during DCS Redis instance creation.

5. Compile code according to the readme file in the source code of the Jedis client. Run the Jedis client to access the chosen DCS Redis instance.