In this Article, I will show How to start quick development with
Spring Data Cassandra. How to create a maven project and add required dependencies.
How to retrieve data using Spring Cassandra Template.
Tools Uses :
1) spring-data-cassandra-1.2.1.RELEASE
2) Apache-cassandra-2.1.6
3) eclipse version Luna 4.4.1.
4) Maven 3.3.3
5) JDK 1.6
Steps to be follow :
1) Create a simple maven project.
2) Add the dependencies and
3) Write a simple program to retrieve data using Spring Cassandra Template.
4) Start the Cassandra server.
5) Run the program and verify the data in cassandra.
Add the given dependency to spring-data-cassandra API,
org.springframework.data spring-data-cassandra 1.2.1.RELEASE
Complete pom.xml file code is Here,
pom.xml
4.0.0 com.devjavasource.cassandra SpringDataCassandraExample 0.0.1-SNAPSHOT jar SpringDataCassandraExample http://maven.apache.org UTF-8 junit junit 3.8.1 test com.datastax.cassandra cassandra-driver-core 2.1.6 org.springframework.data spring-data-cassandra 1.2.1.RELEASE
Write a simple program to retrieve data using Spring Cassandra Template :
This program will do the following,
1) Create a Cluster object.
Cluster cluster = null;
cluster = Cluster.builder().addContactPoint("127.0.0.1").build();
A cluster object maintains a permanent connection to one of
the cluster nodes. builder() is a static method of Cluster class.
2) Create a session object
private static Session session;
session = cluster.connect("devjavasource");
Here “devjavasource” is the existed keyspace, I am using the same.
we can create a session object by passing key space name as parameter
to connect() method of cluster class.
3) Create CassandraOperations :
CassandraOperations is interface that helps to do Operations like select, insert, delete…etc
for interacting with Cassandra.
CassandraOperations cassandraOps = new CassandraTemplate(session);
We can create query using QueryBuilder class.
// List of columns, that has to be selected from table users
final String[] columns = new String[] { "id", "address", "name" };
// Select query creation with QueryBuilder class
Select select = QueryBuilder.select(columns).from("users");
select.where(QueryBuilder.eq("id", 11101));
//Execute a query and get the results
final List<User> results = cassandraOps.select(select, User.class);
Complete Source code is Here,
App.java
package com.devjavasource.cassandra.SpringDataCassandraExample;
import java.util.List;
import org.springframework.data.cassandra.core.CassandraOperations;
import org.springframework.data.cassandra.core.CassandraTemplate;
import com.datastax.driver.core.Cluster;
import com.datastax.driver.core.Session;
import com.datastax.driver.core.querybuilder.QueryBuilder;
import com.datastax.driver.core.querybuilder.Select;
import com.devjavasource.cassandra.dto.User;
public class App {
private static Cluster cluster;
private static Session session;
public static void main(String[] args) {
try {
cluster = Cluster.builder().addContactPoint("127.0.0.1").build();
session = cluster.connect("devjavasource");
CassandraOperations cassandraOps = new CassandraTemplate(session);
final String[] columns = new String[] { "id", "address", "name" };
Select select = QueryBuilder.select(columns).from("users");
select.where(QueryBuilder.eq("id", 11101));
final List<User> results = cassandraOps.select(select, User.class);
System.out.println("Spring Data Cassandra Example");
System.out.println("==============================");
for (User user : results) {
System.out.println("User Id is: " + user.getId());
System.out.println("User Address is: " + user.getAddress());
System.out.println("User Name is: " + user.getName());
}
} catch (Exception e) {
e.printStackTrace();
} finally {
cluster.close();
}
}
}
User.java
package com.devjavasource.cassandra.dto;
import org.springframework.data.cassandra.mapping.PrimaryKey;
import org.springframework.data.cassandra.mapping.Table;
@Table
public class User {
@PrimaryKey
private int id;
private String address;
private String name;
public User(int id, String address, String name) {
this.id = id;
this.address = address;
this.name = name;
}
public int getId() {
return id;
}
public String getAddress() {
return address;
}
public String getName() {
return name;
}
@Override
public String toString() {
return "User [id=" + id + ", address=" + address + ", name=" + name
+ "]";
}
}
4) Start the Cassandra server :
Cassandra server should be up and running.
If the server is not running, run the server using following command.
Command to start Casandra server is,
C:\apache-cassandra-2.1.6\bin>cassandra.bat -f
5) Run Maven project :
Select and Run As -> Java Application.
Out Put :
Spring Data Cassandra Example ============================== User Id is: 11101 User Address is: Oakland User Name is: john
Verify the data in cassandra :
Start cqlsh shell and use key space “devjavasource” and query
for the table Users.
You can download complete project, Here
*** Venkat – Happy leaning ****