最近有個老專案想逐步將新業務的資料放到新的資料庫，以前的業務還得連線以前的資料庫，於是需要整合多資料來源 。

多資料來源實際上是繼承了AbstractRoutingDataSource類，這個類最終實現了DataSource介面，DataSource裡只有一個getConnection方法，資料庫每次訪問的時候都要先通過這個方法獲取連線，所有多資料來源就是每次訪問資料庫之前動態的改變資料來源。

在請求前改變資料來源當然需要用到SpringAOP，自定義註解操作

專案結構

下面上程式碼：

首先是依賴：

 <!--資料庫連線-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <!--sqlserver-->
        <dependency>
            <groupId>com.microsoft.sqlserver</groupId>
            <artifactId>mssql-jdbc</artifactId>
            <scope>runtime</scope>
        </dependency>
        <!--mybatis-plus-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.1.2</version>
        </dependency>
        <!--資料庫連線池-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.8</version>
        </dependency>
 
　　　　　　
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-aop</artifactId>
        </dependency>

yml配置資料來源

server:
  port: 8888

spring:
  jackson:
    time-zone: GMT+8
    date-format: yyyy-MM-dd HH:mm:ss
  datasource:
    druid:
      first:
        driver
 
-class-name: com.mysql.cj.jdbc.Driver
        type: com.alibaba.druid.pool.DruidDataSource
        jdbc-url: jdbc:mysql://rm-uf6265pj340sc9447oo.mysql.rds.54565.com:3306/dm?serverTimezone=Asia/Shanghai&useSSL=false&allowPublicKeyRetrieval=true&characterEncoding=utf-8
        username: username
        password: password
      second:
        type: com.alibaba.druid.pool.DruidDataSource
        driver
 
-class-name: com.microsoft.sqlserver.jdbc.SQLServerDriver
        jdbc-url: jdbc:sqlserver://39.104.203.222:1433;DatabaseName=TestTLcom
        username: root
        password: 123456

mybatis-plus:
  mapper-locations: classpath*:/mapper/*Mapper.xml
  type-aliases-package: com.zdyl.dynamicdatasourcedemo.entity
  global-config:
    #主鍵型別  0:"資料庫ID自增", 1:"使用者輸入ID",2:"全域性唯一ID (數字型別唯一ID)", 3:"全域性唯一ID UUID";
    id-type: 3
    #欄位策略 0:"忽略判斷",1:"非 NULL 判斷"),2:"非空判斷"
    field-strategy: 2
    #駝峰下劃線轉換
    db-column-underline: true
    #重新整理mapper 除錯神器
    refresh-mapper: true
    #資料庫大寫下劃線轉換
    #capital-mode: true
    #序列介面實現類配置
    #key-generator: com.baomidou.springboot.xxx
    #邏輯刪除配置
    #logic-delete-value: 0
    #logic-not-delete-value: 1
    #自定義填充策略介面實現
    #meta-object-handler: com.baomidou.springboot.xxx
    #自定義SQL注入器
    #sql-injector: com.baomidou.springboot.xxx
  configuration:
    map-underscore-to-camel-case: true
    cache-enabled: false

定義資料庫名稱

/**
 * 資料庫名稱
 */
public interface DataSourceNames {

    String FIRST = "first";
    String SECOND = "second";
}

動態資料來源

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

import javax.sql.DataSource;
import java.util.HashMap;
import java.util.Map;

/**
 * 動態資料來源
 */
public class DynamicDataSource extends AbstractRoutingDataSource {

    private static final ThreadLocal<String> contextHolder = new ThreadLocal<>();

    public DynamicDataSource(DataSource defaultTargetDataSource, Map<String, DataSource> targetDataSources) {

        super.setDefaultTargetDataSource(defaultTargetDataSource);
        super.setTargetDataSources(new HashMap<>(targetDataSources));
        super.afterPropertiesSet();
    }

    @Override
    protected Object determineCurrentLookupKey() {
        return getDataSource();
    }

    public static String getDataSource() {
        return contextHolder.get();
    }

    public static void setDataSource(String dataSource) {
        contextHolder.set(dataSource);
    }

    public static void clearDataSource() {
        contextHolder.remove();
    }
}

配置多資料來源

import com.baomidou.mybatisplus.extension.plugins.PaginationInterceptor;
import com.zdyl.dynamicdatasourcedemo.dynamicdatasource.DataSourceNames;
import com.zdyl.dynamicdatasourcedemo.dynamicdatasource.DynamicDataSource;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.jdbc.DataSourceBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;

import javax.sql.DataSource;
import java.util.HashMap;
import java.util.Map;

/**
 * 多資料來源配置
 */
@Configuration
@MapperScan("com.zdyl.dynamicdatasourcedemo.**.mapper*")
public class MybatisPluConfig {

    /**
     * 資料來源配置
     * @return
     */
    @Bean
    @ConfigurationProperties(prefix="spring.datasource.druid.first")
    public DataSource firstDataSource() {
        return DataSourceBuilder.create().build();
    }

    @Bean
    @ConfigurationProperties(prefix="spring.datasource.druid.second")
    public DataSource secondDataSource() {
        return DataSourceBuilder.create().build();
    }

    @Bean
    @Primary
    public DynamicDataSource dataSource(DataSource firstDataSource, DataSource secondDataSource){
        Map<String, DataSource> targetDataSources = new HashMap<>();
        targetDataSources.put(DataSourceNames.FIRST, firstDataSource);
        targetDataSources.put(DataSourceNames.SECOND, secondDataSource);
        return new DynamicDataSource(firstDataSource, targetDataSources);
    }

    /**
     * mybatis-plus分頁外掛<br>
     * 文件：http://mp.baomidou.com<br>
     */
    @Bean
    public PaginationInterceptor paginationInterceptor() {
        return new PaginationInterceptor();
    }

}

下面就是自定義註解

import java.lang.annotation.*;

/**
 * 多資料來源註解
 * AOP攔截此註解更換資料來源
 */

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface CurDataSource {

    String name() default "";
}

AOP

import com.zdyl.dynamicdatasourcedemo.dynamicdatasource.DataSourceNames;
import com.zdyl.dynamicdatasourcedemo.dynamicdatasource.DynamicDataSource;
import com.zdyl.dynamicdatasourcedemo.dynamicdatasource.annotation.CurDataSource;
import lombok.extern.slf4j.Slf4j;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.core.Ordered;
import org.springframework.stereotype.Component;

import java.lang.reflect.Method;


/**
 * 多資料來源，切面處理類
 * AOP攔截多資料來源註解 @CurDataSource 註解更換資料來源
 */

@Slf4j
@Aspect
@Component
public class DataSourceAspect implements Ordered {


    /**
     * 切點
     */
    @Pointcut("@annotation(com.zdyl.dynamicdatasourcedemo.dynamicdatasource.annotation.CurDataSource)")
    public void dataSourcePointCut() {

    }

    @Around("dataSourcePointCut()")
    public Object around(ProceedingJoinPoint point) throws Throwable {
        MethodSignature signature = (MethodSignature) point.getSignature();
        Method method = signature.getMethod();
        CurDataSource curDataSource = method.getAnnotation(CurDataSource.class);
        if (curDataSource == null) {
            DynamicDataSource.setDataSource(DataSourceNames.FIRST);
            log.info("set datasource is " + DataSourceNames.FIRST);
        } else {
            DynamicDataSource.setDataSource(curDataSource.name());
            log.info("set datasource is " + curDataSource.name());
        }
        try {
            return point.proceed();
        } finally {
            DynamicDataSource.clearDataSource();
            log.info("clean datasource");
        }
    }

    @Override
    public int getOrder() {
        return 1;
    }
}

最後主啟動了去掉資料來源自動載入

@SpringBootApplication(exclude = DataSourceAutoConfiguration.class)

最後我們來跑起來請求一下，測試一下是否正確

@RestController
public class CfgDeviceController {
    @Resource
    CfgDeviceService cfgDeviceService;
    @Resource
    CfgChargeStartInfoService cfgChargeStartInfoService;

    @GetMapping("/test")
    public void getUser() {

        CfgDevice byId = cfgDeviceService.getById(19);
        System.out.println(byId.toString());
    }

    @CurDataSource(name = DataSourceNames.SECOND)
    @GetMapping("/test1")
    public void getUser1() {
        CfgChargeStartInfo byId = cfgChargeStartInfoService.getById(1);
        System.out.println(byId.toString());
    }
}

至此就整合完了