I tried Cassandra's Object Mapper for Java

A memo when I cut and pasted the sample code in Official DataStax Manual and moved it. ..

Premise

Ubuntu 17.04
Cassandra 3.10 --Casandra Driver 3.2.0 on the Java side

Preparation

Cassandra side

Install Cassandra

$ wget http://ftp.jaist.ac.jp/pub/apache/cassandra/3.10/apache-cassandra-3.10-bin.tar.gz
$ tar -zxvf apache-cassandra-3.10-bin.tar.gz
$ sudo mv apache-cassandra-3.10/ /opt/cassandra

Start Cassandra server
```
$ /opt/cassandra/bin/cassandra
```

Create Keyspace (name: ks)

$ /opt/cassandra/bin/cqlsh 127.0.0.1 -e "\
CREATE KEYSPACE ks\
  WITH REPLICATION = { 'class': 'SimpleStrategy', 'replication_factor': 1 };"

Create Table (name: ʻusers`)

$ /opt/cassandra/bin/cqlsh 127.0.0.1 -e "\
CREATE TABLE ks.users (\
  user_id uuid,\
  name text,\
  strength int,\
  PRIMARY KEY(user_id, name)\
);"

Java side

pom.xml --Add dependencies for cassandra-driver-core and cassandra-driver-mapping

  ```xml:pom.xml
  ...
  <dependency>
      <groupId>com.datastax.cassandra</groupId>
      <artifactId>cassandra-driver-core</artifactId>
      <version>3.2.0</version>
  </dependency>
  <dependency>
      <groupId>com.datastax.cassandra</groupId>
      <artifactId>cassandra-driver-mapping</artifactId>
      <version>3.2.0</version>
  </dependency>
  ...
  ```

Source code --Mapped class

 ```User.java
 package sample;
 
 import com.datastax.driver.mapping.annotations.ClusteringColumn;
 import com.datastax.driver.mapping.annotations.Column;
 import com.datastax.driver.mapping.annotations.Param;
 import com.datastax.driver.mapping.annotations.PartitionKey;
 import com.datastax.driver.mapping.annotations.Table;
 import java.util.UUID;
 
 @Table(keyspace = "ks", name = "users",
     readConsistency = "QUORUM",
     writeConsistency = "QUORUM",
     caseSensitiveKeyspace = false,
     caseSensitiveTable = false)
 public class User {
 
   @PartitionKey
   @Column(name = "user_id")
   private UUID userId;
 
   @ClusteringColumn
   private String name;
 
   private int strength;
 
 
   public User(UUID userId, String name, int strength) {
     this.userId = userId;
     this.name = name;
     this.strength = strength;
   }
 }
 ```

--Main class

    ```Main.java
    package sample;

    import com.datastax.driver.core.Cluster;
    import com.datastax.driver.core.Session;
    import com.datastax.driver.mapping.Mapper;
    import com.datastax.driver.mapping.MappingManager;
    import java.util.UUID;

    public class Main {

      public static void main(String[] args) {
        Cluster cluster = null;
        try {
          cluster = Cluster.builder()
              .addContactPoint("127.0.0.1")
              .build();
          Session session = cluster.connect();
          MappingManager manager = new MappingManager(session);
          Mapper<User> mapper = manager.mapper(User.class);

          User u = new User(UUID.randomUUID(), "John Doe", 9999);
          mapper.save(u);

        } finally {
          if (cluster != null) {
            cluster.close();
          }
        }
      }
    }
    ```

Execution result

After executing the above main class, check from cqlsh whether data has been inserted.

$ /opt/cassandra/bin/cqlsh 127.0.0.1 -e "SELECT * FROM ks.users;"

 user_id                              | name     | strength
--------------------------------------+----------+----------
 e918961b-57c1-4f5d-8c4e-9d08e9ea4e7a | John Doe |     9999

(1 rows)

reference

https://github.com/datastax/java-driver/blob/3.x/manual/README.md
https://github.com/datastax/java-driver/blob/3.x/manual/object_mapper