Getting Started

Apache Cassandra 的 Spring Data 要求 Apache Cassandra 2.1 或更高版本和 Datastax Java Driver 4.0 或更高版本。快速设置和引导工作环境的一种简便方法是在 Spring Tools 中创建基于 Spring 的项目或使用 start.spring.io。

Spring Data for Apache Cassandra requires Apache Cassandra 2.1 or later and Datastax Java Driver 4.0 or later. An easy way to quickly set up and bootstrap a working environment is to create a Spring-based project in Spring Tools or use start.spring.io.

Examples Repository

为了了解该库的工作原理，您可以下载并使用 several examples。

To get a feel for how the library works, you can download and play around with several examples.

Hello World

首先，您需要设置正在运行的 Apache Cassandra 服务器。请参阅 Apache Cassandra Quick Start Guide 以了解有关如何启动 Apache Cassandra 的说明。一旦安装，启动 Cassandra 通常是执行以下命令的问题： CASSANDRA_HOME/bin/cassandra -f。

First, you need to set up a running Apache Cassandra server. See the Apache Cassandra Quick Start Guide for an explanation on how to start Apache Cassandra. Once installed, starting Cassandra is typically a matter of executing the following command: CASSANDRA_HOME/bin/cassandra -f.

要在 STS 中创建一个 Spring 项目，请转到文件 → 新建 → Spring 模板项目 → 简单 Spring 实用程序项目，并在提示时按是，然后输入项目和包名称，例如 org.spring.data.cassandra.example。

To create a Spring project in STS, go to File → New → Spring Template Project → Simple Spring Utility Project and press Yes when prompted. Then enter a project and a package name, such as org.spring.data.cassandra.example.

然后，你可以将以下依赖项声明添加到 pom.xml 文件的 dependencies 部分。

Then you can add the following dependency declaration to your pom.xml file’s dependencies section.

<dependencies>

  <dependency>
    <groupId>org.springframework.data</groupId>
    <artifactId>spring-data-cassandra</artifactId>
    <version>{version}</version>
  </dependency>

</dependencies>

此外，你还应该更改 pom.xml 文件中的 Spring 版本如下：

Also, you should change the version of Spring in the pom.xml file to be as follows:

<spring.version>{springVersion}</spring.version>

如果使用里程碑版本而不是 GA 版本，还需要将 Maven 的 Spring Milestone 存储库的位置添加到 pom.xml 文件中，使其与 <dependencies/> 元素处于同一级别，如下所示：

If using a milestone release instead of a GA release, you also need to add the location of the Spring Milestone repository for Maven to your pom.xml file so that it is at the same level of your <dependencies/> element, as follows:

<repositories>
  <repository>
    <id>spring-milestone</id>
    <name>Spring Maven MILESTONE Repository</name>
    <url>https://repo.spring.io/milestone</url>
  </repository>
</repositories>

存储库也是 browseable here。

The repository is also browseable here.

您还可以浏览所有 Spring 存储库 here。

You can also browse all Spring repositories here.

现在，您可以创建一个简单的 Java 应用程序来存储和读取 Cassandra 中的域对象。

Now you can create a simple Java application that stores and reads a domain object to and from Cassandra.

要执行此操作，首先创建一个简单的域对象类以使其持久化，如下面的示例所示：

To do so, first create a simple domain object class to persist, as the following example shows:

/*
 * Copyright 2020-2024 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
// tag::file[]
package org.springframework.data.cassandra.example;

import org.springframework.data.cassandra.core.mapping.PrimaryKey;
import org.springframework.data.cassandra.core.mapping.Table;

@Table
public class Person {

	@PrimaryKey private final String id;

	private final String name;
	private final int age;

	public Person(String id, String name, int age) {
		this.id = id;
		this.name = name;
		this.age = age;
	}

	public String getId() {
		return id;
	}

	private String getName() {
		return name;
	}

	private int getAge() {
		return age;
	}

	@Override
	public String toString() {
		return String.format("{ @type = %1$s, id = %2$s, name = %3$s, age = %4$d }", getClass().getName(), getId(),
				getName(), getAge());
	}
}
// end::file[]

接下来，创建要运行的主应用程序，如下面的示例所示：

Next, create the main application to run, as the following example shows:

Imperative
Reactive

/*
 * Copyright 2020-2024 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
// tag::file[]
package org.springframework.data.cassandra.example;

import java.util.UUID;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.data.cassandra.core.CassandraOperations;
import org.springframework.data.cassandra.core.CassandraTemplate;
import org.springframework.data.cassandra.core.query.Criteria;
import org.springframework.data.cassandra.core.query.Query;

import com.datastax.oss.driver.api.core.CqlSession;

public class CassandraApplication {

	private static final Log LOG = LogFactory.getLog(CassandraApplication.class);

	private static Person newPerson(String name, int age) {
		return new Person(UUID.randomUUID().toString(), name, age);
	}

	public static void main(String[] args) {

		CqlSession cqlSession = CqlSession.builder().withKeyspace("mykeyspace").build();

		CassandraOperations template = new CassandraTemplate(cqlSession);

		Person jonDoe = template.insert(newPerson("Jon Doe", 40));

		LOG.info(template.selectOne(Query.query(Criteria.where("id").is(jonDoe.getId())), Person.class).getId());

		template.truncate(Person.class);
		cqlSession.close();
	}

}
// end::file[]

/*
 * Copyright 2020-2024 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
// tag::file[]
package org.springframework.data.cassandra.example;

import reactor.core.publisher.Mono;

import java.util.UUID;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.data.cassandra.core.ReactiveCassandraOperations;
import org.springframework.data.cassandra.core.ReactiveCassandraTemplate;
import org.springframework.data.cassandra.core.cql.session.DefaultBridgedReactiveSession;
import org.springframework.data.cassandra.core.query.Criteria;
import org.springframework.data.cassandra.core.query.Query;

import com.datastax.oss.driver.api.core.CqlSession;

public class ReactiveCassandraApplication {

	private static final Log LOG = LogFactory.getLog(ReactiveCassandraApplication.class);

	private static Person newPerson(String name, int age) {
		return new Person(UUID.randomUUID().toString(), name, age);
	}

	public static void main(String[] args) {

		CqlSession cqlSession = CqlSession.builder().withKeyspace("mykeyspace").build();

		 ReactiveCassandraOperations template = new ReactiveCassandraTemplate(new DefaultBridgedReactiveSession(cqlSession));

    Mono<Person> jonDoe = template.insert(newPerson("Jon Doe", 40));

    jonDoe.flatMap(it -> template.selectOne(Query.query(Criteria.where("id").is(it.getId())), Person.class))
				.doOnNext(it -> LOG.info(it.toString()))
        .then(template.truncate(Person.class))
        .block();

		cqlSession.close();
	}

}
// end::file[]

即使在这么简单的例子中，也有一些值得注意的事情：

Even in this simple example, there are a few notable things to point out:

You can create an instance of CassandraTemplate (or ReactiveCassandraTemplate for reactive usage) with a Cassandra CqlSession.
You must annotate your POJO as a Cassandra @Table entity and also annotate the @PrimaryKey. Optionally, you can override these mapping names to match your Cassandra database table and column names.
You can either use raw CQL or the DataStax QueryBuilder API to construct your queries.