Lindorm:Java dışı Cassandra CQL sürücüleri ile uygulama geliştirin

Ön koşullar

• LindormTable için CQL uç noktasını edindiniz. Lindorm örnek konsolunda LindormTable sekmesine tıklayın, Cassandra-compatible Endpoints bölümünü genişletin ve CQL Connection için VPC veya genel adresi edinin. Adres ld-bp***42 biçimindedir. Varsayılan kullanıcı adı ve parola root değerindedir.

• Programlama diliniz için sürücüyü indirin ve yükleyin. Daha fazla bilgi için bkz. Cassandra istemci sürücüleri.

Python CQL sürücüsü ile LindormTable erişimi

1. DataStax Python bağımlılık paketini yükleyin. Daha fazla bilgi için bkz. Python için SDK'yı yükleme.

   # Install a specific version (Version 3.x is recommended).
   pip install cassandra-driver==3.19.0
   # Install the latest version.
   pip install cassandra-driver

2. Aşağıdaki örnekte LindormTable erişimi gösterilmektedir.

   #!/usr/bin/env python
   # -*- coding: UTF-8 -*-
   import logging
   import sys
   from cassandra.cluster import Cluster
   from cassandra.auth import PlainTextAuthProvider
   logging.basicConfig(stream=sys.stdout, level=logging.INFO)
   cluster = Cluster(
       # Enter the CQL endpoint for LindormTable. You do not need to specify the port.
       contact_points=["ld-bp17j28j2y7pm****-proxy-lindorm.lindorm.rds.aliyuncs.com"],
       # Enter your username and password. The default for both is root.
       auth_provider=PlainTextAuthProvider("cassandra", "****"))
   session = cluster.connect()
   # Create a keyspace.
   session.execute(
                   "CREATE KEYSPACE IF NOT EXISTS testKeyspace WITH replication = {'class':'SimpleStrategy', 'replication_factor':1};");
   # Create a table.
   session.execute(
                   "CREATE TABLE IF NOT EXISTS testKeyspace.testTable (id int PRIMARY KEY, name text,age int,address text);");
   # Insert data.
   session.execute(
                   "INSERT INTO testKeyspace.testTable (id, name, age, address) VALUES ( 1, 'testname', 11, 'hangzhou');");
   # Query data.
   rows = session.execute(
                   "SELECT * FROM testKeyspace.testTable ;");
   # Print each row to the console.
   for row in rows:
       print("# row: {}".format(row))
   # Close the session.
   session.shutdown()
   # Shut down the cluster.
   cluster.shutdown()

C++ CQL sürücüsü ile LindormTable erişimi

1. C++ bağımlılık paketini indirin. Daha fazla bilgi için bkz. DataStax C++ Driver.

2. Aşağıdaki örnekte LindormTable erişimi gösterilmektedir.

   CassFuture* connect_future = NULL;
   CassCluster* cluster = cass_cluster_new();
   CassSession* session = cass_session_new();
   // Enter the CQL endpoint for LindormTable. You do not need to specify the port.
   char* hosts = "ld-bp17j28j2y7pm****-proxy-lindorm.lindorm.rds.aliyuncs.com";
   // Establish a connection.
   cass_cluster_set_contact_points(cluster, hosts);
   connect_future = cass_session_connect(session, cluster);
   // Execute a query.
   if (cass_future_error_code(connect_future) == CASS_OK) {
       CassFuture* close_future = NULL;
       const char* query = "SELECT  name FROM testKeyspace.testTable ";
       CassStatement* statement = cass_statement_new(query, 0);
       CassFuture* result_future = cass_session_execute(session, statement);
       if (cass_future_error_code(result_future) == CASS_OK) {
         // Obtain the query result.
         const CassResult* result = cass_future_get_result(result_future);
         const CassRow* row = cass_result_first_row(result);
         if (row) {
           const CassValue* value = cass_row_get_column_by_name(row, "name");
           // Print the result.
           const char* name;
           size_t name_length;
           cass_value_get_string(value, &name, &name_length);
           printf("release_version: '%.*s'\n", (int)name_length, name);
         }
         cass_result_free(result);
       } else {
         // Handle exceptions.
         const char* message;
         size_t message_length;
         cass_future_error_message(result_future, &message, &message_length);
         fprintf(stderr, "Unable to run query: '%.*s'\n", (int)message_length, message);
       }
       cass_statement_free(statement);
       cass_future_free(result_future);
       // Manually release resources.
       close_future = cass_session_close(session);
       cass_future_wait(close_future);
       cass_future_free(close_future);
     } else {
       // Handle exceptions.
       const char* message;
       size_t message_length;
       cass_future_error_message(connect_future, &message, &message_length);
       fprintf(stderr, "Unable to connect: '%.*s'\n", (int)message_length, message);
     }
     cass_future_free(connect_future);
     cass_cluster_free(cluster);
     cass_session_free(session);           

Node.js CQL sürücüsü ile LindormTable erişimi

1. Node.js bağımlılık paketini yükleyin.

   npm install cassandra-driver 

2. Aşağıdaki örnekte LindormTable erişimi gösterilmektedir.

   const cassandra = require('cassandra-driver');
   /**
   * Enter the CQL endpoint for LindormTable. You do not need to specify the port. Set the DC name to datacenter1.
   * Replace 'Username' and 'Password' with your credentials. The default for both is root.
   */
   const client = new cassandra.Client({ contactPoints: ['ld-bp17j28j2y7pm****-proxy-lindorm.lindorm.rds.aliyuncs.com'], localDataCenter: 'datacenter1', credentials: { username: 'Username', password: 'Password' } });
   client.connect()
   .then(() => client.execute("CREATE KEYSPACE IF NOT EXISTS lindormtest WITH replication = {'class': 'SimpleStrategy', 'replication_factor': '2' }"))
   .then(() => client.execute("CREATE TABLE IF NOT EXISTS lindormtest.nodejs (name text PRIMARY KEY, age int)"))
   .then(() => {
    return client.execute("INSERT INTO lindormtest.nodejs (name, age) VALUES ('lindorm', 10)");
   })
   .then(() => {
    return client.execute("SELECT name, age FROM lindormtest.nodejs WHERE name = 'lindorm' ");
   })
   .then(result => {
    const row = result.first();
    console.log('Obtained row: ', row);
    const p = row.age;
   })
   .finally(() => client.shutdown());
               

Go CQL sürücüsü ile LindormTable erişimi

1. GoCQL yükleyin.

   go get github.com/gocql/gocql

2. Aşağıdaki örnekte LindormTable erişimi gösterilmektedir.

   package main
   import (
       "fmt"
       "log"
       "github.com/gocql/gocql"
   )
   func main() {
       // Enter the CQL endpoint for LindormTable. You do not need to specify the port.
       cluster := gocql.NewCluster("ld-bp17j28j2y7pm****-proxy-lindorm.lindorm.rds.aliyuncs.com")
       cluster.Authenticator = gocql.PasswordAuthenticator{
           Username:"Username",
           Password: "Password",
       }
       session, _ := cluster.CreateSession()
       defer session.Close()
       // Create a keyspace.
       if err := session.Query(`CREATE KEYSPACE ks WITH replication = {'class': 'SimpleStrategy', 'replication_factor': 2}`).Exec(); err != nil {
           log.Fatal(err)
       }
       // Create a table.
       if err := session.Query(`CREATE TABLE ks.tb (cn1 text PRIMARY KEY, cn2 text, cn3 text)`).Exec(); err != nil {
           log.Fatal(err)
       }
       // Insert a value.
       if err := session.Query(`INSERT INTO ks.tb (cn1, cn2, cn3) VALUES (?, ?, ?)`,
           "v11", "v12", "v13").Exec(); err != nil {
           log.Fatal(err)
       }
       var column1 string
       var column2 string
       if err := session.Query(`SELECT cn1, cn2 FROM ks.tb WHERE cn1 = ?`,
           "v11").Consistency(gocql.One).Scan(&column1, &column2); err != nil {
           log.Fatal(err)
       }
       fmt.Println("ALL values:", column1, column2)
       var column3 string
       // Iterate over the results.
       iter := session.Query(`SELECT * FROM ks.tb WHERE cn1 = ? `, "v11").Iter()
       for iter.Scan(&column1, &column2, &column3) {
           fmt.Println("ALL value:", column1, column2, column3)
       }
       if err := iter.Close(); err != nil {
           log.Fatal(err)
       }
   }