spring-data-cassanra的簡單使用

時間  2019-11-18
標籤 spring data cassanra 簡單 使用 欄目 Spring 简体版
原文   原文鏈接

以前寫了JAVA操做cassandra驅動包，如今來看看spring-data對cassandra的支持。這裏是spring-data-cassandra的官方文檔：http://docs.spring.io/spring-data/cassandra/docs/1.5.0.M1/reference/html/  html

這個目錄下還有api、版本日誌等：http://docs.spring.io/spring-data/cassandra/docs/1.5.0.M1/java

  1. 引入jar包
    <!-- 這裏對應的是cassandra3.0以後的版本 -->
<dependency>
   <groupId>org.springframework.data</groupId>
    <artifactId>spring-data-cassandra</artifactId>
    <version>1.5.0.M1</version>
</dependency>
  2. 定義域模型（實體類）
    不存在複合主鍵的狀況：
    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
{
    // 主鍵
    @PrimaryKey
    private String id;

    // 列名 與數據庫列名一致時可不加
    @Column(value = "name")
    private String name;

    private int age;

    // 支持構造函數
    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 + "]";
    }

}

    對應的CQL建表語句spring

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

    能夠看出和JPA的註解很相似，不一樣的是cassandra主鍵用的是@PrimaryKey，並且容許使用構造函數。
    若是存在複合主鍵，則要先映射一個主鍵的實體類，再映射一個包含這個主鍵的實體類數據庫

    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
{

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

    // 集羣鍵
    @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 + "]";
    }

}

     對應的CQL建表語句express

    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) 對應主鍵類裏的ordering = Ordering.DESCENDING，按照name降序存儲，只有集羣鍵才能在建表時設置降序存儲。
    其實還有更加複雜的複合分區鍵、複合集羣鍵組合成的主鍵，看懂了上面應該就能觸類旁通了，並且用的很少，這裏就不寫了。apache

  3. 定義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);
}

    咱們能夠看看繼承的CrudRepository這個倉庫接口類api

    /*
 * 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();
}

    這裏面實現了一組CURD方法，若是要寫一些條件查詢的話能夠參考session

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

    這裏要注意的是cassandra支持的查詢是有限制的，能夠參考這篇文章http://zhaoyanblog.com/archives/265.html 。3.0以後的版本改善了許多（如上面的查詢3.0如下的版本是不支持的，name爲非主鍵字段），一個是支持了非主鍵的條件查詢，一個是下降了集羣鍵的查詢限制條件，這裏最好本身在cql中測試一下。
    spring-data-cassandra文檔裏還提到一個分頁的倉庫接口類PagingAndSortingRepository，這個繼承自CrudRepository，並且提供了2個分頁方法。可是通過測試是不能用的。。至少我沒有測試經過，不知道是沒有實現（比較傾向於這個，cassandra分頁的確比較麻煩），仍是本身沒有正確使用。app

  4. application.xml配置文件
    看名字就知道spring-data-cassandra是和spring一塊兒使用的，下面的配置只是最最基本的，更多的配置選項能夠參考 https://my.oschina.net/u/2392555/blog/469893 這篇文章。
    <?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
    ">
    
    <!-- 引入屬性文件 -->
    <context:property-placeholder location="classpath:cassandra.properties" />
     
    <!-- 自動掃描(自動注入) -->
    <context:component-scan base-package="com.my" />
    
    <!-- 註解方式配置事物 -->
    <tx:annotation-driven transaction-manager="transactionManager" />
    
    <!-- spring-cassandra -->
    <cassandra:cluster contact-points="${cassandra_contactpoints}" port="${cassandra_port}" username="${cassandra_username}" password="${cassandra_password}" />
    
    <!-- 當前使用scheam -->
      <cassandra:session keyspace-name="${cassandra_keyspace}" />
      
    <!-- orm -->
     <cassandra:mapping />
     
    <!-- 類型轉換 -->
      <cassandra:converter />
      
    <!-- cassandra operater -->
      <cassandra:template id="cqlTemplate" />
      
    <!-- spring data 接口 -->
      <cassandra:repositories base-package="com.my.repository" />

</beans>

    這個配置文件都有註釋，沒什麼可講的，惟一要注意的是<cassandra:template id="cqlTemplate" /> ，官方文檔上寫的是<cassandra:template id="cassandraTemplate" />，通過測試官方文檔上寫的不能使用，改成上面的就行了。
    其中cassandra.properties文件配置less

    #cassandra數據庫鏈接
#節點ip
cassandra_contactpoints=192.168.3.89
#端口
cassandra_port=9042
#當前操做鍵空間
cassandra_keyspace=mydb
#登陸用戶名
cassandra_username=cassandra
#登陸密碼
cassandra_password=cassandra
  5. 使用測試
    cassandra數據庫person表中數據以下：

    測試方法：
    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()
    {
        //經過Repository查詢
        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());
        }
        
        //經過Repository 自定義查詢查詢
        List<Person> list = personRepository.findByIdAndName("1", "one");
        System.out.println("==>findByIdAndName:");
        for (Person person : list)
        {
            System.out.println(person.toString());
        }
        //經過cassandraOperations查詢
        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());

    }

}

    打印結果


    這裏麪包含2種使用方法，一個是使用本身定義的倉庫接口類，另外一個是spring-data-cassandra提供的CassandraOperations類。CassandraOperations使用方式不少，上面只是列舉了一種，其餘具體應用官方文檔都有說明。

  6. 到這裏就告一段落了，官方文檔還有不少內容，等有時間再去慢慢看了。
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