Spring Boot 动态数据源（yml配置，多数据源自动切换）

1、在启动类添加注解，注册动态多数据源：

@SpringBootApplication
@Import({DynamicDataSourceRegister.class}) // 注册动态多数据源
public class OrangeplusApplication extends WebMvcConfigurerAdapter {

    protected final static Logger logger = LoggerFactory.getLogger(OrangeplusApplication.class);
    public static void main(String[] args) {
        SpringApplication.run(OrangeplusApplication.class, args);
        logger.info("Application is success!");
    }
}

2、yml配置文件中数据源配置内容为：

spring:
  profiles: dev
  datasource:
    url: jdbc:mysql://127.0.0.1:3306/orangeplus?autoReconnect=true&useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull
    username: root
    password: 123456
    driver-class-name: com.mysql.jdbc.Driver

# 更多数据源
custom:
  profiles: dev
  datasource:
    names: ds1,ds2
    ds1:
      driver-class-name: oracle.jdbc.driver.OracleDriver
      url: jdbc:oracle:thin:@localhost:1521:oracle
      username: root
      password: orcl#ncu
    ds2:
      driver-class-name: com.mysql.jdbc.Driver
      url: jdbc:mysql://localhost:3306/orangeplus2?autoReconnect=true&useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull
      username: root
      password: 123456

3、在需要的方法上使用注解指定数据源，简单代码示例：

@Service
public class StudentService {

    @Autowired
    private JdbcTemplate jdbcTemplate;

    // MyBatis的Mapper方法定义接口
    @Autowired
    private StudentMapper studentMapper;

    @TargetDataSource(name="ds2")
    public List<Student> likeName(String name){
        return studentMapper.likeName(name);
    }

    public List<Student> likeNameByDefaultDataSource(String name){
        return studentMapper.likeName(name);
    }

    /**
     * 不指定数据源使用默认数据源
     */
    public List<Student> getList(){
        String sql = "SELECT ID,NAME,SCORE_SUM,SCORE_AVG, AGE   FROM STUDENT";
        return (List<Student>) jdbcTemplate.query(sql, new RowMapper<Student>(){

            @Override
            public Student mapRow(ResultSet rs, int rowNum) throws SQLException {
                Student stu = new Student();
                stu.setId(rs.getInt("ID"));
                stu.setAge(rs.getInt("AGE"));
                stu.setName(rs.getString("NAME"));
                stu.setSumScore(rs.getString("SCORE_SUM"));
                stu.setAvgScore(rs.getString("SCORE_AVG"));
                return stu;
            }

        });
    }

    /**
     * 指定数据源
     */
    @TargetDataSource(name="ds1")
    public List<Student> getListByDs1(){
        String sql = "SELECT ID,NAME,SCORE_SUM,SCORE_AVG, AGE   FROM STUDENT";
        return (List<Student>) jdbcTemplate.query(sql, new RowMapper<Student>(){

            @Override
            public Student mapRow(ResultSet rs, int rowNum) throws SQLException {
                Student stu = new Student();
                stu.setId(rs.getInt("ID"));
                stu.setAge(rs.getInt("AGE"));
                stu.setName(rs.getString("NAME"));
                stu.setSumScore(rs.getString("SCORE_SUM"));
                stu.setAvgScore(rs.getString("SCORE_AVG"));
                return stu;
            }

        });
    }

    /**
     * 指定数据源
     */
    @TargetDataSource(name="ds2")
    public List<Student> getListByDs2(){
        String sql = "SELECT ID,NAME,SCORE_SUM,SCORE_AVG, AGE   FROM STUDENT";
        return (List<Student>) jdbcTemplate.query(sql, new RowMapper<Student>(){

            @Override
            public Student mapRow(ResultSet rs, int rowNum) throws SQLException {
                Student stu = new Student();
                stu.setId(rs.getInt("ID"));
                stu.setAge(rs.getInt("AGE"));
                stu.setName(rs.getString("NAME"));
                stu.setSumScore(rs.getString("SCORE_SUM"));
                stu.setAvgScore(rs.getString("SCORE_AVG"));
                return stu;
            }

        });
    }
}

要注意的是，在使用MyBatis时，注解@TargetDataSource 不能直接在接口类Mapper上使用。
按上面的代码中StudentMapper为接口，实例代码如下：

public interface StudentMapper {

    // 多数据源注解 @TargetDataSource 不可以在这里使用
    List<Student> likeName(String name);

    Student getById(int id);

    String getNameById(int id);

}

请将下面几个类放到Spring Boot项目中：
DynamicDataSource.java

public class DynamicDataSource extends AbstractRoutingDataSource {

    @Override
    protected Object determineCurrentLookupKey() {
        return DynamicDataSourceContextHolder.getDataSourceType();
    }

}

DynamicDataSourceAspect.java

@Aspect
@Order(-1)// 保证该AOP在@Transactional之前执行
@Component
public class DynamicDataSourceAspect {

    private static final Logger logger = LoggerFactory.getLogger(DynamicDataSourceAspect.class);

    @Before("@annotation(ds)")
    public void changeDataSource(JoinPoint point, TargetDataSource ds) throws Throwable {
        String dsId = ds.name();
        if (!DynamicDataSourceContextHolder.containsDataSource(dsId)) {
            logger.error("数据源[{}]不存在，使用默认数据源 > {}", ds.name(), point.getSignature());
        } else {
            logger.debug("Use DataSource : {} > {}", ds.name(), point.getSignature());
            DynamicDataSourceContextHolder.setDataSourceType(ds.name());
        }
    }

    @After("@annotation(ds)")
    public void restoreDataSource(JoinPoint point, TargetDataSource ds) {
        logger.debug("Revert DataSource : {} > {}", ds.name(), point.getSignature());
        DynamicDataSourceContextHolder.clearDataSourceType();
    }

}

DynamicDataSourceContextHolder.java

public class DynamicDataSourceContextHolder {

    private static final ThreadLocal<String> contextHolder = new ThreadLocal<String>();
    public static List<String> dataSourceIds = new ArrayList<>();

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

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

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

    /**
     * 判断指定DataSrouce当前是否存在
     *
     * @param dataSourceId
     */
    public static boolean containsDataSource(String dataSourceId){
        return dataSourceIds.contains(dataSourceId);
    }
}

DynamicDataSourceRegister.java

/**
 * 动态数据源注册<br/>
 * 启动动态数据源请在启动类中（如SpringBootSampleApplication）
 * 添加 @Import(DynamicDataSourceRegister.class)
 *
 */
public class DynamicDataSourceRegister
        implements ImportBeanDefinitionRegistrar, EnvironmentAware {

    private static final Logger logger = LoggerFactory.getLogger(DynamicDataSourceRegister.class);

    private ConversionService conversionService = new DefaultConversionService(); 
    private PropertyValues dataSourcePropertyValues;

    // 如配置文件中未指定数据源类型，使用该默认值
    private static final Object DATASOURCE_TYPE_DEFAULT = "org.apache.tomcat.jdbc.pool.DataSource";
    // private static final Object DATASOURCE_TYPE_DEFAULT =
    // "com.zaxxer.hikari.HikariDataSource";

    // 数据源
    private DataSource defaultDataSource;
    private Map<String, DataSource> customDataSources = new HashMap<>();

    @Override
    public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
        Map<Object, Object> targetDataSources = new HashMap<Object, Object>();
        // 将主数据源添加到更多数据源中
        targetDataSources.put("dataSource", defaultDataSource);
        DynamicDataSourceContextHolder.dataSourceIds.add("dataSource");
        // 添加更多数据源
        targetDataSources.putAll(customDataSources);
        for (String key : customDataSources.keySet()) {
            DynamicDataSourceContextHolder.dataSourceIds.add(key);
        }

        // 创建DynamicDataSource
        GenericBeanDefinition beanDefinition = new GenericBeanDefinition();
        beanDefinition.setBeanClass(DynamicDataSource.class);
        beanDefinition.setSynthetic(true);
        MutablePropertyValues mpv = beanDefinition.getPropertyValues();
        mpv.addPropertyValue("defaultTargetDataSource", defaultDataSource);
        mpv.addPropertyValue("targetDataSources", targetDataSources);
        registry.registerBeanDefinition("dataSource", beanDefinition);

        logger.info("Dynamic DataSource Registry");
    }

    /**
     * 创建DataSource
     *
     * @param type
     * @param driverClassName
     * @param url
     * @param username
     * @param password
     * @return
     */
    @SuppressWarnings("unchecked")
    public DataSource buildDataSource(Map<String, Object> dsMap) {
        try {
            Object type = dsMap.get("type");
            if (type == null)
                type = DATASOURCE_TYPE_DEFAULT;// 默认DataSource

            Class<? extends DataSource> dataSourceType;
            dataSourceType = (Class<? extends DataSource>) Class.forName((String) type);

            String driverClassName = dsMap.get("driver-class-name").toString();
            String url = dsMap.get("url").toString();
            String username = dsMap.get("username").toString();
            String password = dsMap.get("password").toString();

            DataSourceBuilder factory = DataSourceBuilder.create().driverClassName(driverClassName).url(url)
                    .username(username).password(password).type(dataSourceType);
            return factory.build();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 加载多数据源配置
     */
    @Override
    public void setEnvironment(Environment env) {
        initDefaultDataSource(env);
        initCustomDataSources(env);
    }

    /**
     * 初始化主数据源
     *
     */
    private void initDefaultDataSource(Environment env) {
        // 读取主数据源
        RelaxedPropertyResolver propertyResolver = new RelaxedPropertyResolver(env, "spring.datasource.");
        Map<String, Object> dsMap = new HashMap<>();
        dsMap.put("type", propertyResolver.getProperty("type"));
        dsMap.put("driver-class-name", propertyResolver.getProperty("driver-class-name"));
        dsMap.put("url", propertyResolver.getProperty("url"));
        dsMap.put("username", propertyResolver.getProperty("username"));
        dsMap.put("password", propertyResolver.getProperty("password"));

        defaultDataSource = buildDataSource(dsMap);

        dataBinder(defaultDataSource, env);
    }

    /**
     * 为DataSource绑定更多数据
     *
     * @param dataSource
     * @param env
     */
    private void dataBinder(DataSource dataSource, Environment env){
        RelaxedDataBinder dataBinder = new RelaxedDataBinder(dataSource);
        //dataBinder.setValidator(new LocalValidatorFactory().run(this.applicationContext));
        dataBinder.setConversionService(conversionService);
        dataBinder.setIgnoreNestedProperties(false);//false
        dataBinder.setIgnoreInvalidFields(false);//false
        dataBinder.setIgnoreUnknownFields(true);//true
        if(dataSourcePropertyValues == null){
            Map<String, Object> rpr = new RelaxedPropertyResolver(env, "spring.datasource").getSubProperties(".");
            Map<String, Object> values = new HashMap<>(rpr);
            // 排除已经设置的属性
            values.remove("type");
            values.remove("driver-class-name");
            values.remove("url");
            values.remove("username");
            values.remove("password");
            dataSourcePropertyValues = new MutablePropertyValues(values);
        }
        dataBinder.bind(dataSourcePropertyValues);
    }

    /**
     * 初始化更多数据源
     *
     */
    private void initCustomDataSources(Environment env) {
        // 读取配置文件获取更多数据源，也可以通过defaultDataSource读取数据库获取更多数据源
        RelaxedPropertyResolver propertyResolver = new RelaxedPropertyResolver(env, "custom.datasource.");
        String dsPrefixs = propertyResolver.getProperty("names");
        for (String dsPrefix : dsPrefixs.split(",")) {// 多个数据源
            Map<String, Object> dsMap = propertyResolver.getSubProperties(dsPrefix + ".");
            DataSource ds = buildDataSource(dsMap);
            customDataSources.put(dsPrefix, ds);
            dataBinder(ds, env);
        }
    }

}

TargetDataSource.java

/**
 * 在方法上使用，用于指定使用哪个数据源
 *
 */
@Target({ ElementType.METHOD, ElementType.TYPE })
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface TargetDataSource {
    String name();
}

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