java 项目中配置多个数据源

java 项目于中配置多个数据库的示例

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.example</groupId>
    <artifactId>multi-datasource-demo</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.5</version>
        <relativePath/>
    </parent>

    <properties>
        <java.version>1.8</java.version>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>

        <dependency>
            <groupId>com.oracle.database.jdbc</groupId>
            <artifactId>ojdbc8</artifactId>
            <scope>runtime</scope>
        </dependency>

        <dependency>
            <groupId>org.postgresql</groupId>
            <artifactId>postgresql</artifactId>
            <scope>runtime</scope>
        </dependency>

        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.5.2</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

java代码中示例

支持三种不同类型数据库(MySQL、Oracle、PostgreSQL)的连接配置

package com.example.config;

import org.springframework.beans.factory.annotation.Qualifier;
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 org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;

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

@Configuration
public class DataSourceConfig {

    @Bean(name = "primaryDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.primary")
    @Primary
    public DataSource primaryDataSource() {
        return DataSourceBuilder.create().build();
    }

    @Bean(name = "secondaryDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.secondary")
    public DataSource secondaryDataSource() {
        return DataSourceBuilder.create().build();
    }

    @Bean(name = "thirdDataSource")
    @ConfigurationProperties(prefix = "spring.datasource.third")
    public DataSource thirdDataSource() {
        return DataSourceBuilder.create().build();
    }

    @Bean
    public AbstractRoutingDataSource dataSource(
            @Qualifier("primaryDataSource") DataSource primaryDataSource,
            @Qualifier("secondaryDataSource") DataSource secondaryDataSource,
            @Qualifier("thirdDataSource") DataSource thirdDataSource) {
        
        Map<Object, Object> targetDataSources = new HashMap<>();
        targetDataSources.put("primary", primaryDataSource);
        targetDataSources.put("secondary", secondaryDataSource);
        targetDataSources.put("third", thirdDataSource);

        AbstractRoutingDataSource routingDataSource = new AbstractRoutingDataSource() {
            @Override
            protected Object determineCurrentLookupKey() {
                return DataSourceContextHolder.getDataSourceType();
            }
        };

        routingDataSource.setDefaultTargetDataSource(primaryDataSource);
        routingDataSource.setTargetDataSources(targetDataSources);
        return routingDataSource;
    }
}

采用动态数据源路由机制，通过AbstractRoutingDataSource实现运行时数据源切换

package com.example.config;

public class DataSourceContextHolder {
    
    private static final ThreadLocal<String> CONTEXT_HOLDER = new ThreadLocal<>();

    public static void setDataSourceType(String dataSourceType) {
        CONTEXT_HOLDER.set(dataSourceType);
    }

    public static String getDataSourceType() {
        return CONTEXT_HOLDER.get();
    }

    public static void clearDataSourceType() {
        CONTEXT_HOLDER.remove();
    }
}

使用注解方式(@TargetDataSource)简化数据源切换操作，提高代码可读性

package com.example.config;

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.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

@Aspect
@Component
@Order(1)
public class DataSourceAspect {

    @Pointcut("@annotation(com.example.config.TargetDataSource)")
    public void dataSourcePointCut() {
    }

    @Around("dataSourcePointCut()")
    public Object around(ProceedingJoinPoint point) throws Throwable {
        TargetDataSource annotation = point.getTarget()
                .getClass()
                .getDeclaredMethod(point.getSignature().getName(), 
                        ((Class<?>[]) point.getSignature().getParameterTypes()))
                .getAnnotation(TargetDataSource.class);

        if (annotation != null) {
            DataSourceContextHolder.setDataSourceType(annotation.name());
        }

        try {
            return point.proceed();
        } finally {
            DataSourceContextHolder.clearDataSourceType();
        }
    }
}


package com.example.config;

import java.lang.annotation.*;

@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface TargetDataSource {
    String name();
}

项目中配置

server:
  port: 8080

spring:
  datasource:
    primary:
      jdbc-url: jdbc:mysql://localhost:3306/primary_db?useSSL=false&serverTimezone=UTC
      username: root
      password: root
      driver-class-name: com.mysql.cj.jdbc.Driver
      hikari:
        maximum-pool-size: 20
        minimum-idle: 5
    
    secondary:
      jdbc-url: jdbc:oracle:thin:@localhost:1521:xe
      username: system
      password: oracle
      driver-class-name: oracle.jdbc.OracleDriver
      hikari:
        maximum-pool-size: 20
        minimum-idle: 5
    
    third:
      jdbc-url: jdbc:postgresql://localhost:5432/third_db
      username: postgres
      password: postgres
      driver-class-name: org.postgresql.Driver
      hikari:
        maximum-pool-size: 20
        minimum-idle: 5

logging:
  level:
    com.example: debug

项目中使用示例

package com.example.service;

import com.example.config.TargetDataSource;
import com.example.entity.User;
import java.util.List;

public interface UserService {
    
    @TargetDataSource(name = "primary")
    List<User> getUsersFromPrimary();
    
    @TargetDataSource(name = "secondary")
    List<User> getUsersFromSecondary();
    
    @TargetDataSource(name = "third")
    List<User> getUsersFromThird();
    
    @TargetDataSource(name = "primary")
    User saveUserToPrimary(User user);
}


package com.example.service.impl;

import com.example.entity.User;
import com.example.mapper.UserMapper;
import com.example.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;

@Service
public class UserServiceImpl implements UserService {
    
    @Autowired
    private UserMapper userMapper;

    @Override
    public List<User> getUsersFromPrimary() {
        return userMapper.selectAll();
    }

    @Override
    public List<User> getUsersFromSecondary() {
        return userMapper.selectAll();
    }

    @Override
    public List<User> getUsersFromThird() {
        return userMapper.selectAll();
    }

    @Override
    public User saveUserToPrimary(User user) {
        userMapper.insert(user);
        return user;
    }
}


package com.example.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.example.entity.User;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Select;
import java.util.List;

@Mapper
public interface UserMapper extends BaseMapper<User> {
    
    @Select("SELECT * FROM users")
    List<User> selectAll();
    
    int insert(User user);
}


package com.example.entity;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;

@TableName("users")
public class User {
    
    @TableId(type = IdType.AUTO)
    private Long id;
    
    private String name;
    
    private String email;
    
    private Integer age;

    // Constructors
    public User() {}

    public User(String name, String email, Integer age) {
        this.name = name;
        this.email = email;
        this.age = age;
    }

    // Getters and Setters
    public Long getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public Integer getAge() {
        return age;
    }

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

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", email='" + email + '\'' +
                ", age=" + age +
                '}';
    }
}


package com.example.entity;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;

@TableName("users")
public class User {
    
    @TableId(type = IdType.AUTO)
    private Long id;
    
    private String name;
    
    private String email;
    
    private Integer age;

    // Constructors
    public User() {}

    public User(String name, String email, Integer age) {
        this.name = name;
        this.email = email;
        this.age = age;
    }

    // Getters and Setters
    public Long getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public Integer getAge() {
        return age;
    }

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

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", email='" + email + '\'' +
                ", age=" + age +
                '}';
    }
}


package com.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}