SpringBoot+MyBatisPlus+Mysql多数据源配置（二）

傷城~ 2023-10-07 17:13 34阅读 0赞

### 多数据源配置（二）：代码实现多数据源配置 ###

由于MyBatisPlus对于MyBatis只做升级不做修改，是无条件兼容的，所以我现在建Spring的项目都是直接整合MyBatisPlus，就是为了方便快速开发。SpringBoot项目整合MyBatisPlus，配置多数据源的主从同步，跟传统的单数据源配置还是有很大的区别。关键是要做好读写分离，**主库增、删、改，从库查**。

### 一、新建一个SpringBoot项目 ###

略

### 二、导入相关依赖 ###

<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-aop</artifactId>
    </dependency>
    
    <dependency>
        <groupId>com.baomidou</groupId>
        <artifactId>mybatis-plus-boot-starter</artifactId>
        <version>3.3.2</version>
    </dependency>
    
    <dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid-spring-boot-starter</artifactId>
        <version>1.2.4</version>
    </dependency>

### 三、yaml中配置多数据源 ###

spring:
      datasource:
        type: com.alibaba.druid.pool.DruidDataSource
        driver-class-name: com.mysql.cj.jdbc.Driver
        druid:
          master:
            username: your_name
            password: your_pwd
            url: jdbc:mysql://*.*.*.*:*/*?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
            driver-class-name: com.mysql.cj.jdbc.Driver
            initialSize: 1
            minIdle: 1
            maxActive: 20
          slave:
            username: your_name
            password: your_pwd
            url: jdbc:mysql://*.*.*.*:*/*?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
            driver-class-name: com.mysql.cj.jdbc.Driver
            initialSize: 1
            minIdle: 1
            maxActive: 20

### 四、代码实现 ###

**1.新建一个枚举类DBTypeEnum，标识主从数据源**

public enum DBTypeEnum {
        
        MASTER("master"), SLAVE("slave");
    
        private String value;
        DBTypeEnum(String value){
        
            this.value = value;
        }
    
        public String getValue() {
        
            return value;
        }
    }

**2.多数据源切换处理类DBContextHolder**

public class DBContextHolder {
        
    
        private static final ThreadLocal<DBTypeEnum> contextHolder = new InheritableThreadLocal<>();
    
        public static void set(DBTypeEnum dbType) {
        
            contextHolder.set(dbType);
        }
    
        public static DBTypeEnum get() {
        
            return contextHolder.get();
        }
    
        public static void master() {
        
            set(DBTypeEnum.MASTER);
            System.out.println("切换到master数据源");
        }
    
        public static void slave() {
        
            set(DBTypeEnum.SLAVE);
            System.out.println("切换到slave数据源");
        }
    
        public static void cleanAll() {
        
            contextHolder.remove();
        }
    }

**3.动态数据源MyRoutingDataSource**

public class MyRoutingDataSource extends AbstractRoutingDataSource {
        
        @Override
        protected Object determineCurrentLookupKey() {
        
            return DBContextHolder.get();
        }
    }

**4.数据源配置类DataSourceConfig**

@Configuration
    @MapperScan("com.ebt.demo.mapper") //对应mapper接口所在包扫描
    public class DataSourceConfig {
        
    	/**
         * mybatisPlus分页配置
         */
        @Bean
        public PaginationInterceptor paginationInterceptor() {
        
            PaginationInterceptor paginationInterceptor = new PaginationInterceptor();
            return paginationInterceptor;
        }
    
    	/**
         * 主数据源
         */
        @Bean
        @ConfigurationProperties("spring.datasource.druid.master")
        public DataSource masterDataSource() {
        
            return DruidDataSourceBuilder.create().build();
        }
    
    	/**
         * 从数据源
         */
        @Bean
        @ConfigurationProperties("spring.datasource.druid.slave")
        public DataSource slaveDataSource() {
        
            return DruidDataSourceBuilder.create().build();
        }
    
        /**
         * 动态数据源配置
         */
        @Bean
        public DataSource myRoutingDataSource(@Qualifier("masterDataSource") DataSource masterDataSource,
                                              @Qualifier("slaveDataSource") DataSource slaveDataSource) {
        
            Map<Object, Object> targetDataSource = new HashMap<>();
            targetDataSource.put(DBTypeEnum.MASTER, masterDataSource);
            targetDataSource.put(DBTypeEnum.SLAVE, slaveDataSource);
            MyRoutingDataSource myRoutingDataSource = new MyRoutingDataSource();
            //找不到用默认数据源
            myRoutingDataSource.setDefaultTargetDataSource(masterDataSource);
            //可选择目标数据源
            myRoutingDataSource.setTargetDataSources(targetDataSource);
            return myRoutingDataSource;
        }
    
        @Bean("sqlSessionFactory")
        public SqlSessionFactory sqlSessionFactory() throws Exception {
        
            MybatisSqlSessionFactoryBean sqlSessionFactory = new MybatisSqlSessionFactoryBean();
            sqlSessionFactory.setDataSource(myRoutingDataSource(masterDataSource(),slaveDataSource()));
            //mapper下xml文件位置
            sqlSessionFactory.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath:/mapper/*.xml"));
    
            MybatisConfiguration configuration = new MybatisConfiguration();
            configuration.setJdbcTypeForNull(JdbcType.NULL);
            configuration.setMapUnderscoreToCamelCase(true);
            configuration.setCacheEnabled(false);
            sqlSessionFactory.setConfiguration(configuration);
            sqlSessionFactory.setGlobalConfig(globalConfig());
            return sqlSessionFactory.getObject();
        }
    
        /**
         * mybatisPlus自定义配置
         */
        public GlobalConfig globalConfig(){
        
            GlobalConfig globalConfig = new GlobalConfig();
            GlobalConfig.DbConfig dbConfig = new GlobalConfig.DbConfig();
            dbConfig.setIdType(IdType.AUTO);
            globalConfig.setDbConfig(dbConfig);
            return globalConfig;
        }
    }

**5.自定义注解，在service上可以指定方法调用master或slave**

@Target({
        ElementType.METHOD,ElementType.TYPE})
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    public @interface DataSource {
        
        DBTypeEnum value() default DBTypeEnum.MASTER;
    }

**6.切面儿AOP配置（这一步很关键）**

> 对于MybatisPlus在Service层已经实现的方法（get\*、list\*、page\*、count\*、select\*、query\*、save\*、update\*、remove\*、delete\*），就直接在切面这边定义“读”或者“写”，切换对应的数据源。而对于其他的方法，则需要加上@DataSource的注解来区分。

@Aspect
    @Order(-1)
    @Component
    public class DataSourceAop {
        
        @Pointcut("(execution(* com.test.service..*.get*(..)) " +
                "|| execution(* com.test.service..*.list*(..)) " +
                "|| execution(* com.test.service..*.page*(..)) " +
                "|| execution(* com.test.service..*.count*(..)) " +
                "|| execution(* com.test.service..*.select*(..)) " +
                "|| execution(* com.test.service..*.query*(..)))")
        public void readPointcut() {
        
        }
    
        @Pointcut("execution(* com.test.service..*.save*(..)) " +
                "|| execution(* com.test.service..*.update*(..)) " +
                "|| execution(* com.test.service..*.remove*(..)) " +
                "|| execution(* com.test.service..*.delete*(..)) ")
        public void writePointcut() {
        
        }
    
        @Pointcut("@within(com.test.util.DataSource) " +
                "|| @annotation(com.test.util.DataSource)")
        public void pointcut(){
        
        }
    
        @Before("readPointcut()")
        public void read() {
        
            DBContextHolder.slave();
        }
    
        @Before("writePointcut()")
        public void write() {
        
            DBContextHolder.master();
        }
    
        @Before("pointcut() && @annotation(dataSource)")
        public void doBefore(DataSource dataSource){
        
            String value = dataSource.value().getValue();
            if (value.equals(DBTypeEnum.MASTER.getValue())) {
        
                DBContextHolder.master();
            }
            if (value.equals(DBTypeEnum.SLAVE.getValue())) {
        
                DBContextHolder.slave();
            }
    
        }
    
        @After("readPointcut()")
        public void cleanRead() {
        
            DBContextHolder.cleanAll();
        }
    
        @After("writePointcut()")
        public void cleanWrite() {
        
            DBContextHolder.cleanAll();
        }
    
        @After("pointcut()")
        public void clean() {
        
            DBContextHolder.cleanAll();
        }
    }

**至此，我们已经全部整合完毕了，接下来就可以测试了！**