spring-data-cassanra的简单使用

2023-08-19 20:42:22

之前写了JAVA操作cassandra驱动包，现在来看看spring-data对cassandra的支持。这里是spring-data-cassandra的官方文档：http://docs.spring.io/spring-data/cassandra/docs/1.5.0.M1/reference/html/

这个目录下还有api、版本日志等：http://docs.spring.io/spring-data/cassandra/docs/1.5.0.M1/

  1. 引入jar包 
    <!-- 这里对应的是cassandra3.0之后的版本 -->
    
<dependency>
    
   <groupId>org.springframework.data</groupId>
    
    <artifactId>spring-data-cassandra</artifactId>
    
    <version>1.5.0.M1</version>
    
</dependency>
  2. 定义域模型（实体类）
    不存在复合主键的情况： 
    package com.my.domin.pojo;

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

@Table
    
public class Person
    
{
    
    // 主键
    
    @PrimaryKey
    
    private String id;

    // 列名 与数据库列名一致时可不加
    
    @Column(value = "name")
    
    private String name;

    private int age;

    // 支持构造函数
    
    public Person(String id, String name, int age)
    
    {
    
        this.id = id;
    
        this.name = name;
    
        this.age = age;
    
    }

    public String getId()
    
    {
    
        return id;
    
    }

    public void setId(String id)
    
    {
    
        this.id = id;
    
    }

    public String getName()
    
    {
    
        return name;
    
    }

    public void setName(String name)
    
    {
    
        this.name = name;
    
    }

    public int getAge()
    
    {
    
        return age;
    
    }

    public void setAge(int age)
    
    {
    
        this.age = age;
    
    }

    @Override
    
    public String toString()
    
    {
    
        return "Person [id=" + id + ", name=" + name + ", age=" + age + "]";
    
    }

}

    对应的CQL建表语句

    CREATE TABLE mydb.person (
    
    id text PRIMARY KEY,
    
    age int,
    
    name text
    
)

    可以看出和JPA的注解很类似，不同的是cassandra主键用的是@PrimaryKey，而且允许使用构造函数。
    如果存在复合主键，则要先映射一个主键的实体类，再映射一个包含这个主键的实体类

    package com.my.domin.pojo;

import org.springframework.cassandra.core.Ordering;
    
import org.springframework.cassandra.core.PrimaryKeyType;
    
import org.springframework.data.cassandra.mapping.PrimaryKeyClass;
    
import org.springframework.data.cassandra.mapping.PrimaryKeyColumn;

@PrimaryKeyClass
    
public class Person2Key
    
{

    // 分区键
    
    @PrimaryKeyColumn(name = "id", ordinal = 0, type = PrimaryKeyType.PARTITIONED)
    
    private String id;

    // 集群键
    
    @PrimaryKeyColumn(name = "name", ordinal = 1, type = PrimaryKeyType.CLUSTERED, ordering = Ordering.DESCENDING)
    
    private String name;

    public String getId()
    
    {
    
        return id;
    
    }

    public void setId(String id)
    
    {
    
        this.id = id;
    
    }

    public String getName()
    
    {
    
        return name;
    
    }

    public void setName(String name)
    
    {
    
        this.name = name;
    
    }

    @Override
    
    public String toString()
    
    {
    
        return "Person2Key [id=" + id + ", name=" + name + "]";
    
    }

}
    package com.my.domin.pojo;

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

@Table(value = "person2")
    
public class Person2
    
{
    
    @PrimaryKey
    
    private Person2Key pKey;

    private int age;

    public Person2Key getpKey()
    
    {
    
        return pKey;
    
    }

    public void setpKey(Person2Key pKey)
    
    {
    
        this.pKey = pKey;
    
    }

    public int getAge()
    
    {
    
        return age;
    
    }

    public void setAge(int age)
    
    {
    
        this.age = age;
    
    }

    @Override
    
    public String toString()
    
    {
    
        return "Person2 [pKey=" + pKey + ", age=" + age + "]";
    
    }

}

    对应的CQL建表语句

    CREATE TABLE mydb.person2 (
    
    id text,
    
    name text,
    
    age int,
    
    PRIMARY KEY (id, name)
    
) WITH CLUSTERING ORDER BY (name DESC)

    其中的WITH CLUSTERING ORDER BY (name DESC) 对应主键类里的ordering = Ordering.DESCENDING，按照name降序存储，只有集群键才能在建表时设置降序存储。
    其实还有更加复杂的复合分区键、复合集群键组合成的主键，看懂了上面应该就能举一反三了，而且用的不多，这里就不写了。

  3. 定义spring-data接口 
    package com.my.repository;

import java.util.List;

import org.springframework.data.cassandra.repository.Query;
    
import org.springframework.data.repository.CrudRepository;
    
import org.springframework.stereotype.Repository;

import com.my.domin.pojo.Person2;

@Repository
    
public interface PersonRepository extends CrudRepository<Person2, String>
    
{
    
    @Query("select * from Person2 where id= ?1 and name= ?2")
    
    List<Person2> findByIdAndName(String id, String name);
    
}

    我们可以看看继承的CrudRepository这个仓库接口类

    /*
    
 * Copyright 2008-2011 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
    
 *
    
 *      http://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.
    
 */
    
package org.springframework.data.repository;

import java.io.Serializable;

/**
    
 * Interface for generic CRUD operations on a repository for a specific type.
    
 *
    
 * @author Oliver Gierke
    
 * @author Eberhard Wolff
    
 */
    
@NoRepositoryBean
    
public interface CrudRepository<T, ID extends Serializable> extends Repository<T, ID> {

    /**
    
     * Saves a given entity. Use the returned instance for further operations as the save operation might have changed the
    
     * entity instance completely.
    
     *
    
     * @param entity
    
     * @return the saved entity
    
     */
    
    <S extends T> S save(S entity);

    /**
    
     * Saves all given entities.
    
     *
    
     * @param entities
    
     * @return the saved entities
    
     * @throws IllegalArgumentException in case the given entity is {@literal null}.
    
     */
    
    <S extends T> Iterable<S> save(Iterable<S> entities);

    /**
    
     * Retrieves an entity by its id.
    
     *
    
     * @param id must not be {@literal null}.
    
     * @return the entity with the given id or {@literal null} if none found
    
     * @throws IllegalArgumentException if {@code id} is {@literal null}
    
     */
    
    T findOne(ID id);

    /**
    
     * Returns whether an entity with the given id exists.
    
     *
    
     * @param id must not be {@literal null}.
    
     * @return true if an entity with the given id exists, {@literal false} otherwise
    
     * @throws IllegalArgumentException if {@code id} is {@literal null}
    
     */
    
    boolean exists(ID id);

    /**
    
     * Returns all instances of the type.
    
     *
    
     * @return all entities
    
     */
    
    Iterable<T> findAll();

    /**
    
     * Returns all instances of the type with the given IDs.
    
     *
    
     * @param ids
    
     * @return
    
     */
    
    Iterable<T> findAll(Iterable<ID> ids);

    /**
    
     * Returns the number of entities available.
    
     *
    
     * @return the number of entities
    
     */
    
    long count();

    /**
    
     * Deletes the entity with the given id.
    
     *
    
     * @param id must not be {@literal null}.
    
     * @throws IllegalArgumentException in case the given {@code id} is {@literal null}
    
     */
    
    void delete(ID id);

    /**
    
     * Deletes a given entity.
    
     *
    
     * @param entity
    
     * @throws IllegalArgumentException in case the given entity is {@literal null}.
    
     */
    
    void delete(T entity);

    /**
    
     * Deletes the given entities.
    
     *
    
     * @param entities
    
     * @throws IllegalArgumentException in case the given {@link Iterable} is {@literal null}.
    
     */
    
    void delete(Iterable<? extends T> entities);

    /**
    
     * Deletes all entities managed by the repository.
    
     */
    
    void deleteAll();
    
}

    这里面实现了一组CURD方法，如果要写一些条件查询的话可以参考

    @Query("select * from Person where id= ?1 and name= ?2 ALLOW FILTERING")
    
 List<Person> findByIdAndName(String id, String name);

    这里要注意的是cassandra支持的查询是有限制的，可以参考这篇文章http://zhaoyanblog.com/archives/265.html 。3.0之后的版本改善了许多（如上面的查询3.0以下的版本是不支持的，name为非主键字段），一个是支持了非主键的条件查询，一个是降低了集群键的查询限制条件，这里最好自己在cql中测试一下。
    spring-data-cassandra文档里还提到一个分页的仓库接口类PagingAndSortingRepository，这个继承自CrudRepository，而且提供了2个分页方法。但是经过测试是不能用的。。至少我没有测试通过，不知道是没有实现（比较倾向于这个，cassandra分页的确比较麻烦），还是自己没有正确使用。

  4. application.xml配置文件
    看名字就知道spring-data-cassandra是和spring一起使用的，下面的配置只是最最基本的，更多的配置选项可以参考 https://my.oschina.net/u/2392555/blog/469893 这篇文章。 
    <?xml version="1.0" encoding="UTF-8"?>
    
<beans xmlns="http://www.springframework.org/schema/beans"
    
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    
 xmlns:cassandra="http://www.springframework.org/schema/data/cassandra"
    
 xmlns:context="http://www.springframework.org/schema/context"
    
 xmlns:p="http://www.springframework.org/schema/p"
    
 xsi:schemaLocation="http://www.springframework.org/schema/data/cassandra
    
    http://www.springframework.org/schema/data/cassandra/spring-cassandra-1.0.xsd
    
    http://www.springframework.org/schema/data/cassandra/spring-cql.xsd
    
    http://www.springframework.org/schema/data/cassandra/spring-cql-1.0.xsd
    
    http://www.springframework.org/schema/beans
    
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    
    http://www.springframework.org/schema/context
    
    http://www.springframework.org/schema/context/spring-context-3.0.xsd
    
    ">

    <!-- 引入属性文件 -->
    
    <context:property-placeholder location="classpath:cassandra.properties" />

    <!-- 自动扫描(自动注入) -->
    
    <context:component-scan base-package="com.my" />

    <!-- 注解方式配置事物 -->
    
    <tx:annotation-driven transaction-manager="transactionManager" />

    <!-- spring-cassandra -->
    
    <cassandra:cluster contact-points="${cassandra_contactpoints}" port="${cassandra_port}" username="${cassandra_username}" password="${cassandra_password}" />

    <!-- 当前使用scheam -->
    
      <cassandra:session keyspace-name="${cassandra_keyspace}" />

    <!-- orm -->
    
     <cassandra:mapping />

    <!-- 类型转换 -->
    
      <cassandra:converter />

    <!-- cassandra operater -->
    
      <cassandra:template id="cqlTemplate" />

    <!-- spring data 接口 -->
    
      <cassandra:repositories base-package="com.my.repository" />

</beans>

    这个配置文件都有注释，没什么可讲的，唯一要注意的是<cassandra:template id="cqlTemplate" /> ，官方文档上写的是<cassandra:template id="cassandraTemplate" />，经过测试官方文档上写的不能使用，改为上面的就好了。
    其中cassandra.properties文件配置

    #cassandra数据库连接
    
#节点ip
    
cassandra_contactpoints=192.168.3.89
    
#端口
    
cassandra_port=9042
    
#当前操作键空间
    
cassandra_keyspace=mydb
    
#登录用户名
    
cassandra_username=cassandra
    
#登录密码
    
cassandra_password=cassandra
  5. 使用测试
    cassandra数据库person表中数据如下：
    spring-data-cassanra的简单使用
    测试方法： 
    package com.my.serviceImpl;

import java.util.Iterator;
    
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
    
import org.springframework.data.cassandra.core.CassandraOperations;
    
import org.springframework.stereotype.Service;

import com.datastax.driver.core.querybuilder.QueryBuilder;
    
import com.datastax.driver.core.querybuilder.Select;
    
import com.my.domin.pojo.Person;
    
import com.my.repository.PersonRepository;
    
import com.my.service.PersonService;

@Service
    
public class PersonServiceImpl implements PersonService
    
{
    
    @Autowired
    
    private PersonRepository personRepository;

    @Autowired
    
    private CassandraOperations cassandraOperations;

    @Override
    
    public void test()
    
    {
    
        //通过Repository查询
    
        Iterable<Person> iterable = personRepository.findAll();
    
        Iterator<Person> it = iterable.iterator();
    
        System.out.println("==>findAll:");
    
        while (it.hasNext())
    
        {
    
            Person p = it.next();
    
            System.out.println(p.toString());
    
        }

        //通过Repository 自定义查询查询
    
        List<Person> list = personRepository.findByIdAndName("1", "one");
    
        System.out.println("==>findByIdAndName:");
    
        for (Person person : list)
    
        {
    
            System.out.println(person.toString());
    
        }
    
        //通过cassandraOperations查询
    
        Select select = QueryBuilder.select().from("person");
    
        select.where(QueryBuilder.eq("id", "1"));
    
        Person person = cassandraOperations.selectOne(select, Person.class);
    
        System.out.println("==>cassandraOperations:");
    
        System.out.println(person.toString());

    }

}

    打印结果

    spring-data-cassanra的简单使用
    这里面包含2种使用方法，一个是使用自己定义的仓库接口类，另一个是spring-data-cassandra提供的CassandraOperations类。CassandraOperations使用方式很多，上面只是列举了一种，其他具体应用官方文档都有说明。

  6. 到这里就告一段落了，官方文档还有很多内容，等有时间再去慢慢看了。
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