从 Mysql 迁移到 Cassandra Spring boot

Question

我是 Cassandra 的新手，这是第一次，以前从未使用过，到目前为止我们一直使用 Spring Boot 和 MySql 作为我们的数据库，但现在我们计划将我们的数据库迁移到 Cassandra，最低限度代码或没有变化。 这是我们一直在使用的代码示例演示。

配置类

package com.example.demo.config;
import com.zaxxer.hikari.HikariDataSource;
import lombok.Generated;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.data.jpa.repository.config.EnableJpaAuditing;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.Database;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.annotation.EnableTransactionManagement;
import javax.sql.DataSource;
import java.util.HashMap;
import static org.hibernate.cfg.AvailableSettings.*;
@Configuration
@EnableTransactionManagement
@EnableJpaAuditing
@EnableJpaRepositories(entityManagerFactoryRef = "orclEntityManagerFactory", transactionManagerRef = "orclTransactionManager", basePackages = {"com.example.demo.repository"})
@Generated
public class DataSourceConfig {
    @Value("${spring.datasource.driver-class-name}")
    private String orclDbDriver;
    @Value("${spring.datasource.url}")
    private String orclDbConnUrl;
    @Value("${spring.datasource.username}")
    private String orclDbUsername;
    @Value("${spring.datasource.password}")
    private String orclDbPassword;
    @Value("${spring.datasource.poolName}")
    private String dataSourcePoolName;
    @Value("${spring.jpa.properties.hibernate.dialect}")
    private String orclHibernateDialect;
    @Value("${spring.jpa.hibernate.ddl-auto}")
    private String hibernateDDL;
    @Value("${spring.jpa.show-sql}")
    private boolean showSql;
    @Value("${spring.datasource.packagesToScan}")
    private String[] packagesToScan;
    public DataSourceConfig() {
    }
    @Bean
    @Primary
    public DataSource orclDataSource() {
        HikariDataSource dataSource = new HikariDataSource();
        dataSource.setDriverClassName(this.orclDbDriver);
        dataSource.setJdbcUrl(this.orclDbConnUrl);
        dataSource.setUsername(this.orclDbUsername);
        dataSource.setPassword(this.orclDbPassword);
        dataSource.setPoolName(this.dataSourcePoolName);
        return dataSource;
    }
    @Bean
    @Primary
    public LocalContainerEntityManagerFactoryBean orclEntityManagerFactory() {
        LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
        factory.setDataSource(this.orclDataSource());
        factory.setPackagesToScan(this.packagesToScan);
        HibernateJpaVendorAdapter jpaVendorAdapter = new HibernateJpaVendorAdapter();
        jpaVendorAdapter.setDatabase(Database.MYSQL);
        jpaVendorAdapter.setGenerateDdl(Boolean.TRUE);
        jpaVendorAdapter.setShowSql(showSql);
        jpaVendorAdapter.setDatabasePlatform(orclHibernateDialect);
        factory.setJpaVendorAdapter(jpaVendorAdapter);
        HashMap<String, Object> properties = new HashMap();
        properties.put(HBM2DDL_AUTO, this.hibernateDDL);
        properties.put(DIALECT, this.orclHibernateDialect);
        properties.put(STATEMENT_BATCH_SIZE, "500");
        properties.put(ORDER_UPDATES, "true");
        properties.put(ORDER_INSERTS, "true");
        properties.put(GENERATE_STATISTICS, "true");
        factory.setJpaPropertyMap(properties);
        return factory;
    }
    @Bean
    @Primary
    public JpaTransactionManager orclTransactionManager() {
        JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(this.orclEntityManagerFactory().getObject());
        return transactionManager;
    }
}

控制器类

import com.example.demo.entity.Child;
import com.example.demo.repository.ChildRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import java.sql.Timestamp;
import java.util.List;

@RestController
public class HelloController {
    @Autowired
    private ChildRepository childRepository;

    @GetMapping("put")
    public Child getHello() {
        Child child = new Child();
        child.setName("shrikant");
        child.setUpdatedAt(new Timestamp(System.currentTimeMillis()));
        return childRepository.save(child);
    }

    @GetMapping("get")
    public List<Child> hello() {
        return childRepository.findAll();
    }
}

存储库

package com.example.demo.repository;
import com.example.demo.entity.Child;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;
@Repository
public interface ChildRepository extends JpaRepository<Child, Long> {
}

 

应用程序.dev

spring.datasource.url=jdbc:mysql://localhost:3306/student_db?jdbcCompliantTruncation=false&sessionVariables=sql_mode='NO_ENGINE_SUBSTITUTION'&useSSL=false&useServerPrepStmts=false&rewriteBatchedStatements=true&useUnicode=true&characterEncoding=utf8
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL8Dialect
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.poolName=springHikariCp
spring.jpa.generate-ddl=true
spring.jpa.database.schema=student_db
spring.jpa.hibernate.ddl-auto=update
#spring.jpa.hibernate.ddl-auto=none
spring.jpa.show-sql=true
spring.datasource.packagesToScan=com.example.demo.entity
spring.profiles.active=dev

build.gradle

plugins {
    id 'org.springframework.boot' version '2.2.6.RELEASE'
    id 'io.spring.dependency-management' version '1.0.9.RELEASE'
    id 'java'
}
group = 'com.example'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '8'
configurations {
    compileOnly {
        extendsFrom annotationProcessor
    }
}
repositories {
    mavenCentral()
}
dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
    implementation 'org.springframework.boot:spring-boot-starter-web'
    compileOnly 'org.projectlombok:lombok'
    compile 'mysql:mysql-connector-java'  
    annotationProcessor 'org.projectlombok:lombok' 
    testImplementation('org.springframework.boot:spring-boot-starter-test') {
        exclude group: 'org.junit.vintage', module: 'junit-vintage-engine'
    }
}
test {
    useJUnitPlatform()
}

我在 google 的帮助下安装了 Cassandra，并且能够使用 cqlsh 登录。

创建的键空间

CREATE KEYSPACE IF NOT EXISTS mykeyspace WITH replication = {'class':'SimpleStrategy', 'replication_factor':1};

在 Gradle 中添加 Cassandra 依赖项

compile 'org.springframework.boot:spring-boot-starter-data-cassandra'

但是 application.properties 中的配置属性应该是什么，我在 Google 上找不到任何创建自定义数据源的示例，都使用 Spring Boot 自动配置，但我不能这样做，因为这将是一个重大的代码更改。

Answer 1

你需要使用CassandraRepository而不是JpaRepository接口

public interface ChildRepository extends CassandraRepository<Child, Long> { }

您需要在 application.properties 中包含这些属性

spring.data.cassandra.contact-points=127.0.0.1 (or your corresponding connection uri)
spring.data.cassandra.username=<username, if any>
spring.data.cassandra.password=<password, if any>
spring.data.cassandra.keyspace=default
spring.data.cassandra.port=9042
spring.data.cassandra.schema-action=NONE

那你会比较好。但是就像其他人在 cmets 部分所说的那样，您应该了解 Cassandra 的本质是非常重要的。如果您不根据查询实现数据模型，则不会成功。