Spring配置动态数据库

首先创建一个SpringWeb项目——dynamicdb（spring-boot2.5.7）

然后引入相关依赖lombok、swagger2、mybatis-plus，如下：

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.5.7</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>dynamicdb</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>dynamicdb</name>
    <description>dynamicdb</description>
    <properties>
        <java.version>8</java.version>
    </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-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.28</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger2</artifactId>
            <version>2.9.2</version>
        </dependency>
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger-ui</artifactId>
            <version>2.9.2</version>
        </dependency>
 
        <!-- mybatis-plus 依赖 -->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.2</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
<!-- sqlSessionTemplate 依赖 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<!-- spring-boot dynamic 动态数据库依赖-->
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>dynamic-datasource-spring-boot-starter</artifactId>
<version>2.5.6</version>
</dependency>
<!-- druid 动态简易使用依赖 @DS("db1")-->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid-spring-boot-starter</artifactId>
<version>1.1.20</version>
</dependency>  
</dependencies>
?
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
?
</project>

然后在包dynamicdb下面创建controller、mapper、dbmodel， 然后在resource下面创建mapper文件夹及问题，如下图：

然后配置application，启用swagger2和添加mapper扫描，如下：

@EnableSwagger2 @Log4j2 @SpringBootApplication @MapperScan("com.example.dynamicdb.mapper") public class DynamicdbApplication { ? public static void main(String[] args) { SpringApplication.run(DynamicdbApplication.class, args); } }

然后编辑resources下的application.yml，如下：

server:
  port: 8082
  servlet:
    context-path: /api
spring:
  servlet:
    multipart:
      max-file-size: 50MB
      max-request-size: 50MB
  datasource:
    dynamic: #使用动态数据库配置
      primary: db1 # 配置默认数据库
      datasource:
        db1: # 数据源1
          driver-class-name: com.mysql.cj.jdbc.Driver
          url: jdbc:mysql://localhost/db1
          username: root
          password: 1qaz!QAZ
        db2: # 数据源2
          driver-class-name: com.mysql.cj.jdbc.Driver
          url: jdbc:mysql://localhost/db2
          username: root
          password: 1qaz!QAZ
      druid:
        initial-size: 1
        max-active: 20
        min-idle: 1
        max-wait: 60000
  autoconfigure:
    exclude: com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceAutoConfigure # 去除druid配置 
mybatis-plus:
  mapper-locations: classpath:mapper/*.xml #指定resources下的mapper文件夹下是存储映射XML的文件夹然后创建SqlSessionController，使用SqlSession来加载Mapper，代码如下：

@RestController
public class SqlSessionController {
?
?
    @Autowired
    private SqlSession sqlSession;
?
    @GetMapping(value = "/SqlSession/normalSql")
    @ResponseBody
    @ApiOperation(value = "默认查询，从主数据库查询", notes = "当前配置的主数据是db1-primary: db1")
    public List<user> normalSql() {
        //读取第一个数据库的值
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        List<user> users = mapper.test();
        return users;
    }
    @GetMapping(value = "/SqlSession/data_from_db1")
    @ResponseBody
    @DS("db1")
    @ApiOperation(value = "从db1数据库查询数据", notes = "查询db1")
    public List<user> data_from_db1() {
        //读取第一个数据库的值
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        List<user> users = mapper.test();
        return users;
    }
?
    @GetMapping(value = "/SqlSession/data_from_db2")
    @ResponseBody
    @DS("db2")
    @ApiOperation(value = "从db2数据库查询数据", notes = "查询db2")
    public List<user> data_from_db2(Integer id) {
        //读取第二个数据库的值
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        List<user> users = mapper.test();
        return users;
    }
}

代码中使用?@DS("db1")来指定该接口内使用的数据库。

再创建一个MapperController，测试使用Mapper直接访问数据库，如下

@RestController
public class MapperController {
?
    @Autowired
    private UserMapper userMapper;
?
    @GetMapping(value = "/Mapper/normalSql")
    @ResponseBody
    @ApiOperation(value = "使用Mapper查询，从主数据库查询", notes = "当前配置的主数据是db1-primary: db1")
    public List<user> normalSql() {
        //读取第一个数据库的值
        List<user> users = userMapper.test();
        return users;
    }
}