SpringBoot（十一）-- 动态数据源

SpringBoot中使用动态数据源可以实现分布式中的分库技术，比如查询用户 就在用户库中查询，查询订单 就在订单库中查询。

一、配置文件application.properties

# 默认数据源
spring.datasource.url=jdbc:mysql://localhost:3306/consult
spring.datasource.username=myConsult
spring.datasource.password=123456
spring.datasource.driver-class-name=org.gjt.mm.mysql.Driver
# 更多数据源
custom.datasource.names=ds1,ds2 
custom.datasource.ds1.driver-class-name=com.mysql.jdbc.Driver
custom.datasource.ds1.url=jdbc:mysql://localhost:3306/test1
custom.datasource.ds1.username=root 
custom.datasource.ds1.password=123456 
custom.datasource.ds2.driver-class-name=com.mysql.jdbc.Driver
custom.datasource.ds2.url=jdbc:mysql://localhost:3306/test2
custom.datasource.ds2.username=root 
custom.datasource.ds2.password=123456

二、pox.xml

 <!-- aspectj -->
 <dependency>
     <groupId>org.aspectj</groupId>
     <artifactId>aspectjrt</artifactId>
 </dependency>
 <dependency>
     <groupId>org.aspectj</groupId>
     <artifactId>aspectjtools</artifactId>
 </dependency>
 <dependency>
      <groupId>org.aspectj</groupId>
      <artifactId>aspectjweaver</artifactId>
 </dependency>

三、使用aop自定义注解，实现动态切换数据源

1.动态数据源注册器

package com.xsjt.dynamicDataSource;  
import java.util.HashMap;
import java.util.Map;
import javax.sql.DataSource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.MutablePropertyValues;
import org.springframework.beans.PropertyValues;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.GenericBeanDefinition;
import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
import org.springframework.boot.bind.RelaxedDataBinder;
import org.springframework.boot.bind.RelaxedPropertyResolver;
import org.springframework.context.EnvironmentAware;
import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
import org.springframework.core.convert.ConversionService;
import org.springframework.core.convert.support.DefaultConversionService;
import org.springframework.core.env.Environment;
import org.springframework.core.type.AnnotationMetadata;
/**  
 * ClassName:DynamicDataSourceRegister 
 * Date:     2017年11月13日 下午7:40:42
 * @author   Joe  
 * @version    
 * @since    JDK 1.8
 */
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<String, DataSource>();
    
    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); // 注册到Spring容器中
        
        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
     */
    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<String, Object>();
        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<String, Object>(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);
        }
    }
}

2.动态数据源适配器

package com.xsjt.dynamicDataSource;  
import java.util.ArrayList;
import java.util.List;
/**  
 * ClassName:DynamicDataSourceContextHolder 
 * Date:     2017年11月13日 下午7:41:49
 * @author   Joe  
 * @version    
 * @since    JDK 1.8
 */
public class DynamicDataSourceContextHolder {
    private static final ThreadLocal<String> contextHolder = new ThreadLocal<String>();
    public static List<String> dataSourceIds = new ArrayList<String>();
    
    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
     * @return
     */
    public static boolean containsDataSource(String dataSourceId){
        return dataSourceIds.contains(dataSourceId);
    }
}

3.自定义注解

/**  
 * ClassName:TargetDataSource 
 * Date:     2017年11月13日 下午7:42:15
 * @author   Joe  
 * @version    
 * @since    JDK 1.8
 */
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface TargetDataSource {
    String name();
}

4.动态数据源切面

package com.xsjt.dynamicDataSource;  
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;
/**  
 * ClassName:DynamicDataSourceAspect 
 * Date:     2017年11月13日 下午7:44:09
 * @author   Joe  
 * @version    
 * @since    JDK 1.8
 */
@Aspect
//保证该AOP在@Transactional之前执行
@Order(-1)
@Component
public class DynamicDataSourceAspect {
    private static final Logger logger = LoggerFactory.getLogger(DynamicDataSourceAspect.class);
    
    /** 
     * @Description 在方法执行之前执行  @annotation(ds) 会拦截有ds这个注解的方法即有 TargetDataSource这个注解的
     * @param @param point
     * @param @param ds
     * @param @throws Throwable 参数 
     * @return void 返回类型  
     * @throws 
     */
    @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());
        }
    }
    
    /** 
     * @Description 在方法执行之后执行  @annotation(ds) 会拦截有ds这个注解的方法即有 TargetDataSource这个注解的 
     * @param @param point
     * @param @param ds 参数 
     * @return void 返回类型  
     * @throws 
     */
    @After("@annotation(ds)")
    public void restoreDataSource(JoinPoint point, TargetDataSource ds) {
        logger.debug("Revert DataSource : {} > {}", ds.name(), point.getSignature());
        DynamicDataSourceContextHolder.clearDataSourceType();
    }
}

5.继承Spring AbstractRoutingDataSource实现路由切换

package com.xsjt.dynamicDataSource;  
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
/**  
 * ClassName:DynamicDataSource 
 * 继承Spring AbstractRoutingDataSource实现路由切换
 * Date:     2017年11月13日 下午7:49:49
 * @author   Joe  
 * @version    
 * @since    JDK 1.8
 */
public class DynamicDataSource extends AbstractRoutingDataSource {
    
    @Override
    protected Object determineCurrentLookupKey() {
        return DynamicDataSourceContextHolder.getDataSourceType();
    }
}

四、怎么使用自定义的注解动态的切换数据源

只需要在service实现类中 对需要切换数据源的方法上 加上 自定义的注解即可，如：@TargetDataSource(name = "ds2")

五、启动类上添加@Import注解

　　//注册动态多数据源
　　@Import({DynamicDataSourceRegister.class})

六.源码下载

　　https://gitee.com/xbq168/spring-boot-learn