使用spring boot构建动态多数据源

# 使用spring boot构建动态多数据源

多数据源的配置方式有很多种，比较常见的有固定的多数据源，使用注解指定数据源，根据传递的参数指定数据源。个人认为第三种更加灵活---根据参数确定使用的多数据源，其原理与使用注解指定类似

我这里使用的是第二种，**使用注解指定数据源**

## 使用多数据源的背景

多数据源一般用于读写分离的操作，即一个service中使用到了多个数据源

## 核心代码

核心代码包含以下几个类：

* TargetDatasource---注解，指定数据源

* DynamicDataSourceAspect---切面，切换数据源

* DatasourceConfig---数据源配置类，加载yml文件中的数据源相关配置

* DruidDatasourceConfig---数据源配置，将相关对象加载到容器中

* DynamicDataSource---动态数据源相关

* DynamicDataSourceContextHolder---数据源切换相关类

### TargetDatasource

注解类，用于指定数据源的，其中名称是在配置中指定的

~~~Java

/**

* @author leo

*/

@Retention(RetentionPolicy.RUNTIME)

@Target({ElementType.METHOD, ElementType.TYPE})

@Documented

public @interface TargetDatasource {

String name();

}

~~~

### DynamicDataSourceAspect

动态切换数据源，根据注解指定的数据源切换对应的数据源

> **注：** 这里也可以使用参数的形式切换数据源，使用 **JoinPoint** 取出相应的参数，设置到对应的位置即可

* 动态数据源切面

* order 为-1，在其他配置执行前执行

@Aspect

@Order(-1)

@Component

public class DynamicDataSourceAspect {

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

/**

* 切换数据库

*

* @param point

* @param targetDatasource

* @return

* @throws Throwable

*/

@Before("@annotation(targetDatasource)")

public void changeDataSource(JoinPoint point, TargetDatasource targetDatasource) {

String datasourceId = targetDatasource.name();

if (!DynamicDataSourceContextHolder.existDataSource(datasourceId)) {

logger.error("No data source found ...【" + datasourceId + "】");

return;

}

DynamicDataSourceContextHolder.setDataSourceType(datasourceId);

}

* @return void

* @Description: 销毁数据源 在所有的方法执行执行完毕后

@After("@annotation(targetDatasource)")

public void destroyDataSource(JoinPoint point, TargetDatasource targetDatasource) {

DynamicDataSourceContextHolder.clearDataSourceType();

### DatasourceConfig

从yml中读取相应的配置

* 从配置文件中读取相关的多数据源配置

*

* @author leo.z.l

* @create 2019-09-09 14:35

@ConfigurationProperties("spring.datasource")

public class DatasourceConfig {

private Map custom;

private Map druid;

public Map getCustom() {

return custom;

public void setCustom(Map custom) {

this.custom = custom;

public Map getDruid() {

return druid;

public void setDruid(Map druid) {

this.druid = druid;

### DruidDatasourceConfig

核心类，将相关的bean对象注册到容器中，可以使用spring boot默认的配置

* 配置数据源，核心类

* @create 2019-09-07 16:27

@Configuration

@EnableTransactionManagement

public class DruidDatasourceConfig {

private final String SPLIT_DATASOURCE_NAMES = ",";

@Autowired

public DatasourceConfig datasourceConfig;

private LinkedHashMap targetDatasource = new LinkedHashMap<>();

private List customDataSourceNames = new ArrayList<>();

private Logger logger = LogManager.getLogger(DruidDatasourceConfig.class);

private ConversionService conversionService = new DefaultConversionService();

* druid 监控器

@Bean

public ServletRegistrationBean druidServlet() {

ServletRegistrationBean reg = new ServletRegistrationBean();

reg.setServlet(new StatViewServlet());

reg.addUrlMappings("/druid/*");

reg.addInitParameter("loginUsername", "root");

reg.addInitParameter("loginPassword", "root");

return reg;

* 过滤器

public FilterRegistrationBean filterRegistrationBean() {

FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();

filterRegistrationBean.setFilter(new WebStatFilter());

filterRegistrationBean.addUrlPatterns("/*");

filterRegistrationBean.addInitParameter("exclusions", "*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*");

filterRegistrationBean.addInitParameter("profileEnable", "true");

filterRegistrationBean.addInitParameter("principalCookieName", "USER_COOKIE");

filterRegistrationBean.addInitParameter("principalSessionName", "USER_SESSION");

return filterRegistrationBean;

* 默认数据源，取第一个为默认数据源

@Bean(name = "dataSource")

@Primary

public AbstractRoutingDataSource dataSource() {

DynamicDataSource dynamicDataSource = new DynamicDataSource();

initCustomDataSources();

dynamicDataSource.setDefaultTargetDataSource(targetDatasource.get(customDataSourceNames.get(0)));

dynamicDataSource.setTargetDataSources(targetDatasource);

dynamicDataSource.afterPropertiesSet();

return dynamicDataSource;

* 初始化数据源

private void initCustomDataSources() {

// 获取数据源名称

Map druidConfig = datasourceConfig.getDruid();

Map customDatasourceConfig = datasourceConfig.getCustom();

String dataSourceNames = (String) customDatasourceConfig.get("name");

if (StringUtils.isEmpty(dataSourceNames)) {

logger.error("The multiple data source list are empty.");

} else {

Map druidValuesMaps = druidConfig;

MutablePropertyValues dataSourcePropertyValue = new MutablePropertyValues(druidValuesMaps);

for (String dataSourceName : dataSourceNames.split(SPLIT_DATASOURCE_NAMES)) {

try {

Map customerDatasourceConfig = (Map) customDatasourceConfig.get(dataSourceName);

customerDatasourceConfig.forEach((key, value) -> dataSourcePropertyValue.addPropertyValue(key, value));

DataSource ds = initDruidDatasource(dataSourcePropertyValue,dataSourceName);

logger.info("Data source initialization 【" + dataSourceName + "】 successfully ...");

} catch (Exception e) {

logger.error("Data source initialization【" + dataSourceName + "】 failed ...", e);

}

}

private DataSource initDruidDatasource(MutablePropertyValues dataSourcePropertyValue,String dataSourceName) {

DruidDataSource ds = new DruidDataSource();

//获取连接池的类型

String type = dataSourcePropertyValue.get("type").toString();

if (StringUtils.isEmpty(type)) {

logger.info("数据源类型为空！");

return null;

if (!StringUtils.equals(type, DruidDataSource.class.getTypeName())) {

logger.info("数据源类型不匹配！");

RelaxedDataBinder dataBinder = new RelaxedDataBinder(ds);

dataBinder.setConversionService(conversionService);

dataBinder.setIgnoreInvalidFields(false);

dataBinder.setIgnoreNestedProperties(false);

dataBinder.setIgnoreUnknownFields(true);

dataBinder.bind(dataSourcePropertyValue);

ds.setName(dataSourceName);

//druid过滤器

try {

ds.setFilters((String) dataSourcePropertyValue.get("filters"));

} catch (SQLException e) {

logger.error("druid configuration initialization filter", e);

customDataSourceNames.add(dataSourceName);

DynamicDataSourceContextHolder.datasourceId.add(dataSourceName);

targetDatasource.put(dataSourceName, ds);

return ds;

### DynamicDataSource

用于获取数据源

public class DynamicDataSource extends AbstractRoutingDataSource {

* 获得数据源

@Override

protected Object determineCurrentLookupKey() {

return DynamicDataSourceContextHolder.getDataSourceType();

### DynamicDataSourceContextHolder

对数据源操作的一些方法

public class DynamicDataSourceContextHolder {

* 使用ThreadLocal维护变量，ThreadLocal为每个使用该变量的线程提供独立的变量副本，

* 所以每一个线程都可以独立地改变自己的副本，而不会影响其它线程所对应的副本。

private static final ThreadLocal CONTEXT_HOLDER = new ThreadLocal();

* 管理所有的数据源id,用于数据源的判断

public static List datasourceId = new ArrayList();

* @Title: setDataSourceType

* @Description: 设置数据源的变量

* @param dataSourceType

* @throws

public static void setDataSourceType(String dataSourceType){

CONTEXT_HOLDER.set(dataSourceType);

* @Title: getDataSourceType

* @Description: 获得数据源的变量

* @return String

public static String getDataSourceType(){

return CONTEXT_HOLDER.get();

* @Title: clearDataSourceType

* @Description: 清空所有的数据源变量

public static void clearDataSourceType(){

CONTEXT_HOLDER.remove();

* @Title: existDataSource

* @Description: 判断数据源是否已存在

* @return boolean

public static boolean existDataSource(String dataSourceType ){

return datasourceId.contains(dataSourceType);

### 使用方式

直接在对应的方法上标注即可

@Override

@TargetDatasource(name = "db1")

public TradeOrder setPaymentWay(TradeOrder tradeOrder, Consumer consumer) {

consumer.accept(tradeOrder);

return tradeOrder;

### yml配置

~~~yml

# begin

datasource:

custom:

name: db1,db2

db1:

name: db1

type: com.alibaba.druid.pool.DruidDataSource

driver-class-name: com.mysql.jdbc.Driver

url: jdbc:mysql://ipAddress:3306/dev_tdod

username: root

password: 123456

db2:

name: db2

druid:

initial-size: 5

min-idle: 5

async-init: true

async-close-connection-enable: true

max-active: 20

max-wait: 60000

time-between-eviction-runs-millis: 60000

min-evictable-idle-time-millis: 30000

validation-query: SELECT 1 FROM DUAL

test-while-idle: true

test-on-borrow: false

test-on-return: false

pool-prepared-statements: true

max-pool-prepared-statement-per-connection-size: 20

filters: stat,slf4j

# end

[^n]: 钟林--2019-10-03