Java实现数据源的方式

一、利用Spring提供的类实现

1)在yml文件当中配置多数据源

spring:
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    datasource1:
      url: jdbc:mysql://127.0.0.1:3306/datasource1?serverTimezone=UTC&useUnicode=true&characterEncoding=UTF8&useSSL=false
      username: root
      password: root
      initial-size: 1
      min-idle: 1
      max-active: 20
      test-on-borrow: true
      driver-class-name: com.mysql.cj.jdbc.Driver
    datasource2:
      url: jdbc:mysql://127.0.0.1:3306/datasource2?serverTimezone=UTC&useUnicode=true&characterEncoding=UTF8&useSSL=false
      username: root
      password: root
      initial-size: 1
      min-idle: 1
      max-active: 20
      test-on-borrow: true
      driver-class-name: com.mysql.cj.jdbc.Driver

2) 定义一个DataSourceConfig 配置类来配置两个数据源

@Configuration
public class DataSourceConfig {

    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.datasource1")
    public DataSource dataSource1() {
        // 底层自动拿到spring.datasource中的配置, 创建一个DruidDataSource
        return DruidDataSourceBuilder.create().build();
    }

    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.datasource2")
    public DataSource dataSource2() {
        // 底层自动拿到spring.datasource中的配置, 创建一个DruidDataSource
        return DruidDataSourceBuilder.create().build();
    }

    /* @Bean
    public Interceptor dynamicDataSourcePlugin(){
        return new DynamicDataSourcePlugin();
    }
*/

    @Bean
    public DataSourceTransactionManager transactionManager1(DynamicDataSource dataSource){
        DataSourceTransactionManager dataSourceTransactionManager = new DataSourceTransactionManager();
        dataSourceTransactionManager.setDataSource(dataSource);
        return dataSourceTransactionManager;
    }

    @Bean
    public DataSourceTransactionManager transactionManager2(DynamicDataSource dataSource){
        DataSourceTransactionManager dataSourceTransactionManager = new DataSourceTransactionManager();
        dataSourceTransactionManager.setDataSource(dataSource);
        return dataSourceTransactionManager;
    }
}

3)自定义一个类 来 继承 org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;

** 在类里面注入分别注入两个数据源**

  // 写
    @Autowired
    DataSource dataSource1;
    // 读
    @Autowired
    DataSource dataSource2;
        // 返回当前数据源标识
    @Override
    protected Object determineCurrentLookupKey() {
        return name.get();
            }

** 在这个初始化完成之后,进行数据源的注入**

       // 当前使用的数据源标识
    public static ThreadLocal<String> name=new ThreadLocal<>();
    @Override
    public void afterPropertiesSet() {

        // 为targetDataSources初始化所有数据源
        Map<Object, Object> targetDataSources=new HashMap<>();
        targetDataSources.put("W",dataSource1);
        targetDataSources.put("R",dataSource2);

        super.setTargetDataSources(targetDataSources);

        // 为defaultTargetDataSource 设置默认的数据源
        super.setDefaultTargetDataSource(dataSource1);

        super.afterPropertiesSet();
    }

**在service使用指定的数据源 **

@Service
public class FriendImplService implements FriendService {

    @Autowired
    FriendMapper friendMapper;


    @Override
    @WR("R")        // 库2
    public List<Friend> list() {
//        DynamicDataSource.name.set("R");
        return friendMapper.list();
    }

    @Override
    @WR("W")        // 库1
    public void save(Friend friend) {
//        DynamicDataSource.name.set("W");
        friendMapper.save(friend);
    }

}

上面采用注解方式就是,其实利用切面进行数据源的设置,和注释注释方式类似

二、利用mybatis层次实现

1)分别配置两个配置源,单独配置

** 编写WMyBatisConfig配置文件**

@Configuration
// 继承mybatis:
// 1. 指定扫描mapper接口包(主库
// 2. 指定使用sqlSessionFactory是哪个(主库
@MapperScan(basePackages = "com.datasource.dynamic.mybatis.mapper.w",
        sqlSessionFactoryRef="wSqlSessionFactory")
public class WMyBatisConfig {
    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.datasource1")
    public DataSource dataSource1() {
        // 底层自动拿到spring.datasource中的配置, 创建一个DruidDataSource
        return DruidDataSourceBuilder.create().build();
    }

    @Bean
    @Primary
    public SqlSessionFactory wSqlSessionFactory()
            throws Exception {
        final SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean();
        // 指定主库
        sessionFactory.setDataSource(dataSource1());
        // 指定主库对应mapper.xml文件
        /*sessionFactory.setMapperLocations(new PathMatchingResourcePatternResolver()
                .getResources("classpath:mapper/order/*.xml"));*/
        return sessionFactory.getObject();
    }

    @Bean
    @Primary
    public DataSourceTransactionManager wTransactionManager(){
        DataSourceTransactionManager dataSourceTransactionManager = new DataSourceTransactionManager();
        dataSourceTransactionManager.setDataSource(dataSource1());
        return dataSourceTransactionManager;
    }


    @Bean
    public TransactionTemplate wTransactionTemplate(){
        return new TransactionTemplate(wTransactionManager());
    }
}

** 编写RMyBatisConfig 配置文件**


@Configuration
// 继承mybatis:
// 1. 指定扫描mapper接口包(主库)
// 2. 指定使用sqlSessionFactory是哪个(主库)
@MapperScan(basePackages = "com.tuling.datasource.dynamic.mybatis.mapper.w",
        sqlSessionFactoryRef="wSqlSessionFactory")
public class WMyBatisConfig {
    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.datasource1")
    public DataSource dataSource1() {
        // 底层自动拿到spring.datasource中的配置, 创建一个DruidDataSource
        return DruidDataSourceBuilder.create().build();
    }

    @Bean
    @Primary
    public SqlSessionFactory wSqlSessionFactory()
            throws Exception {
        final SqlSessionFactoryBean sessionFactory = new SqlSessionFactoryBean();
        // 指定主库
        sessionFactory.setDataSource(dataSource1());
        // 指定主库对应mapper.xml文件
        /*sessionFactory.setMapperLocations(new PathMatchingResourcePatternResolver()
                .getResources("classpath:mapper/order/*.xml"));*/
        return sessionFactory.getObject();
    }

    @Bean
    @Primary
    public DataSourceTransactionManager wTransactionManager(){
        DataSourceTransactionManager dataSourceTransactionManager = new DataSourceTransactionManager();
        dataSourceTransactionManager.setDataSource(dataSource1());
        return dataSourceTransactionManager;
    }


    @Bean
    public TransactionTemplate wTransactionTemplate(){
        return new TransactionTemplate(wTransactionManager());
    }
}

2) 在serviceImpl实现层 单独调用配置的Mapper代理

 @Autowired
    private RFriendMapper rFriendMapper;

    @Autowired
    private WFriendMapper wFriendMapper;

    // 读-- 读库
    @Override
    public List<Friend> list() {
        return rFriendMapper.list();
    }
  // 保存-- 写库
    @Override
    public void saveW(Friend friend) {
        friend.setName("loulan");
        wFriendMapper.save(friend);
    }

    // 保存-- 读库
    @Override
    public void saveR(Friend friend) {
        friend.setName("loulan");
        rFriendMapper.save(friend);
    }

三、Spring自动化支持

1) 引入pom依赖

 <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>dynamic-datasource-spring-boot-starter</artifactId>
            <version>3.5.0</version>
        </dependency>

2)在service利用注解==@DS实现==


@Service
public class FriendImplService implements FriendService {

    @Autowired
    FriendMapper friendMapper;


    @Override
    @DS("slave_1")  // 从库, 如果按照下划线命名方式配置多个可以指定前缀即可(组名)
    public List<Friend> list() {
        return friendMapper.list();
    }

    @Override
    @DS("master")
    public void save(Friend friend) {
        friendMapper.save(friend);
    }


    @DS("master")
    @DSTransactional
    public void saveAll(){
        // 执行多数据源的操作
    }

}

原文地址:https://blog.csdn.net/weixin_46350527/article/details/129144775

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