Spring Boot動的データ・ソースの実装

シーンの適用

アプリケーションが異なるシーンで異なるデータベースにアクセスする必要がある場合、動的データソースを使用して実装できます.

実装方式:カスタム注釈+AOP

複数のデータ・ソース情報の構成

jdbc1.driverClassName=com.mysql.jdbc.Driver
jdbc1.username=root
jdbc1.password=123456
jdbc1.url=jdbc:mysql://localhost:3306/db_1
jdbc2.driverClassName=com.mysql.jdbc.Driver
jdbc2.username=root
jdbc2.password=654321
jdbc2.url=jdbc:mysql://localhost:3306/db_2

データ・ソース名定数列挙の定義

public enum DataSourceEnum {
    MYSQL_DS, ORACLE_DS
}

動的データソース注記の定義

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target({ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
public @interface DynamicDS {
    DataSourceEnum value() default DataSourceEnum.MYSQL_DS;
}

DataSourceContextHolderの定義

public class DataSourceContextHolder {
    private static ThreadLocal context = new ThreadLocal<>();

    public static void setDataSourceName(DataSourceEnum dsName){
        context.set(dsName);
    }

    public static DataSourceEnum getDataSourceName(){
        return context.get();
    }

    public static void clearDS(){
        context.remove();
    }
}

pom加入AOPの依存

    org.springframework.boot
    spring-boot-starter-aop

AOP実現

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.stereotype.Component;

import java.lang.reflect.Method;

@Aspect
@Component
public class DynamicDataSourceAspect {
    @Before("@annotation(DynamicDS)")
    public void setDataSource(JoinPoint joinPoint)
            throws NoSuchMethodException {
        String methodName = joinPoint.getSignature().getName();
        Class> clazz = joinPoint.getTarget().getClass();
        Method method = clazz.getMethod(methodName,
            ((MethodSignature) joinPoint.getSignature()).getParameterTypes());
        if (method.isAnnotationPresent(DynamicDS.class)) {
            DataSourceContextHolder.setDataSourceName(
                    method.getAnnotation(DynamicDS.class).value());
        }
    }

    @After("@annotation(DynamicDS)")
    public void clearDataSource() {
        DataSourceContextHolder.clearDS();
    }
}

動的データ・ソースの定義

import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;

public class DynamicDataSource extends AbstractRoutingDataSource {
    @Override
    protected Object determineCurrentLookupKey() {
        return DataSourceContextHolder.getDataSourceName();
    }
}

Mybatis構成クラス

import com.alibaba.druid.pool.DruidDataSourceFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.context.EnvironmentAware;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Primary;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.core.env.Environment;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;

import javax.sql.DataSource;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;

@Configuration
@MapperScan(basePackages="com.**.dao")
@PropertySource("classpath:datasource.properties")
public class MybatisConfig implements EnvironmentAware {
    @Primary
    @Bean
    public DataSource mysqlDS() throws Exception {
        Properties prop = new Properties();
        prop.setProperty("username",this.env.getProperty("jdbc1.username"));
        prop.setProperty("password",this.env.getProperty("jdbc1.password"));
        prop.setProperty("url",this.env.getProperty("jdbc1.url"));
        prop.setProperty("driverClassName",this.env.getProperty("jdbc1.driverClassName"));
        return DruidDataSourceFactory.createDataSource(prop);
    }

    @Bean
    public DataSource oracleDS() throws Exception {
        Properties prop = new Properties();
        prop.setProperty("username",this.env.getProperty("jdbc2.username"));
        prop.setProperty("password",this.env.getProperty("jdbc2.password"));
        prop.setProperty("url",this.env.getProperty("jdbc2.url"));
        prop.setProperty("driverClassName",this.env.getProperty("jdbc2.driverClassName"));
        return DruidDataSourceFactory.createDataSource(prop);
    }

    @Bean
    public DataSource dynamicDS(@Qualifier("mysqlDS") DataSource mysqlDS,
                                @Qualifier("oracleDS") DataSource oracleDS) {
        DynamicDataSource dynamicDataSource = new DynamicDataSource();
        dynamicDataSource.setDefaultTargetDataSource(mysqlDS);
        Map

具体的な使用

@DynamicDS(DataSourceEnum.MYSQL_DS)

この注釈を特定のシーンサービス実装クラスに貼り付ける方法

かっこの値は、使用する必要がある特定のデータベースの名前(列挙で定義された定数)

です.