電商訂單項(xiàng)目分正向和逆向兩個(gè)部分：其中正向數(shù)據(jù)庫記錄了訂單的基本信息，包括訂單基本信息、訂單商品信息、優(yōu)惠卷信息、發(fā)票信息、賬期信息、結(jié)算信息、訂單備注信息、收貨人信息等；逆向數(shù)據(jù)庫主要包含了商品的退貨信息和維修信息。數(shù)據(jù)量超過500萬行就要考慮分庫分表和讀寫分離，那么我們在正向操作和逆向操作的時(shí)候，就需要?jiǎng)討B(tài)的切換到相應(yīng)的數(shù)據(jù)庫，進(jìn)行相關(guān)的操作。

現(xiàn)在項(xiàng)目的結(jié)構(gòu)設(shè)計(jì)基本上是基于MVC的，那么數(shù)據(jù)庫的操作集中在dao層完成，主要業(yè)務(wù)邏輯在service層處理，controller層處理請求。假設(shè)在執(zhí)行dao層代碼之前能夠?qū)?shù)據(jù)源（DataSource）換成我們想要執(zhí)行操作的數(shù)據(jù)源，那么這個(gè)問題就解決了

1.實(shí)體類

@Datapublic class Product {private Integer id;private String name;private Double price;}

2.ProductMapper

public interface ProductMapper { @Select('select * from product') public List<Product> findAllProductM(); @Select('select * from product') public List<Product> findAllProductS(); }

3.ProductService

@Service public class ProductService { @Autowired private ProductMapper productMapper; public void findAllProductM(){ // 查詢Master List<Product> allProductM = productMapper.findAllProductM(); System.out.println(allProductM); } public void findAllProductS(){ // 查詢Slave List<Product> allProductS = productMapper.findAllProductS(); System.out.println(allProductS); } }具體實(shí)現(xiàn)

第一步：配置多數(shù)據(jù)源

首先，我們在application.properties中配置兩個(gè)數(shù)據(jù)源

spring.druid.datasource.master.password=root spring.druid.datasource.master.username=root spring.druid.datasource.master.jdbc- url=jdbc:mysql://localhost:3306/product_master? useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC spring.druid.datasource.master.driver-class-name=com.mysql.cj.jdbc.Driver spring.druid.datasource.slave.password=root spring.druid.datasource.slave.username=root spring.druid.datasource.slave.jdbc- url=jdbc:mysql://localhost:3306/product_slave? useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=UTC spring.druid.datasource.slave.driver-class-name=com.mysql.cj.jdbc.Driver在SpringBoot的配置代碼中，我們初始化兩個(gè)數(shù)據(jù)源：@Configuration public class MyDataSourceConfiguratioin { Logger logger = LoggerFactory.getLogger(MyDataSourceConfiguratioin.class); /*** Master data source. */ @Bean('masterDataSource') @ConfigurationProperties(prefix = 'spring.druid.datasource.master') DataSource masterDataSource() { logger.info('create master datasource...'); return DataSourceBuilder.create().build(); } /*** Slave data source. */ @Bean('slaveDataSource') @ConfigurationProperties(prefix = 'spring.druid.datasource.slave') DataSource slaveDataSource() { logger.info('create slave datasource...'); return DataSourceBuilder.create().build(); } @Bean @Primary DataSource primaryDataSource(@Autowired @Qualifier('masterDataSource')DataSource masterDataSource, @Autowired @Qualifier('masterDataSource')DataSource slaveDataSource){logger.info('create routing datasource...'); Map<Object, Object> map = new HashMap<>(); map.put('masterDataSource', masterDataSource); map.put('slaveDataSource', slaveDataSource); RoutingDataSource routing = new RoutingDataSource(); routing.setTargetDataSources(map); routing.setDefaultTargetDataSource(masterDataSource); return routing; }}

第二步：編寫RoutingDataSource然后，我們用Spring內(nèi)置的RoutingDataSource，把兩個(gè)真實(shí)的數(shù)據(jù)源代理為一個(gè)動(dòng)態(tài)數(shù)據(jù)源:

public class RoutingDataSource extends AbstractRoutingDataSource { @Override protected Object determineCurrentLookupKey() { return RoutingDataSourceContext.getDataSourceRoutingKey(); } }

第三步：編寫RoutingDataSourceContext用于存儲(chǔ)當(dāng)前需要切換為哪個(gè)數(shù)據(jù)源

public class RoutingDataSourceContext { // holds data source key in thread local: static final ThreadLocal<String> threadLocalDataSourceKey = new ThreadLocal<>(); public static String getDataSourceRoutingKey() { String key = threadLocalDataSourceKey.get(); return key == null ? 'masterDataSource' : key; } public RoutingDataSourceContext(String key) { threadLocalDataSourceKey.set(key); } public void close() { threadLocalDataSourceKey.remove(); }}

測試（一下代碼為controller中代碼）

@GetMapping('/findAllProductM')public String findAllProductM() {String key = 'masterDataSource';RoutingDataSourceContext routingDataSourceContext = new RoutingDataSourceContext(key);productService.findAllProductM();return 'master';}@GetMapping('/findAllProductS')public String findAllProductS() {String key = 'slaveDataSource'; RoutingDataSourceContext routingDataSourceContext = new RoutingDataSourceContext(key); productService.findAllProductS(); return 'slave';}

以上代碼即可實(shí)現(xiàn)數(shù)據(jù)源動(dòng)態(tài)切換

以上代碼是可行的，但是，需要讀數(shù)據(jù)庫的地方，就需要加上一大段RoutingDataSourceContext

ctx = ...代碼，使用起來十分不便。以下是優(yōu)化方案

我們可以申明一個(gè)自定義注解，將以上RoutingDataSourceContext中的值，放在注解的value屬性中，

然后定義一個(gè)切面類，當(dāng)我們在方法上標(biāo)注自定義注解的時(shí)候，執(zhí)行切面邏輯，獲取到注解中的值，set到RoutingDataSourceContext中，從而實(shí)現(xiàn)通過注解的方式，來動(dòng)態(tài)切換數(shù)據(jù)源

以下是代碼實(shí)現(xiàn)：

注解類

@Target(ElementType.METHOD) @Retention(RetentionPolicy.RUNTIME) public @interface RoutingWith { String value() default 'master'; }

切面類：

@Aspect @Component public class RoutingAspect { @Around('@annotation(routingWith)') public Object routingWithDataSource(ProceedingJoinPoint joinPoint, RoutingWith routingWith) throws Throwable { String key = routingWith.value(); RoutingDataSourceContext ctx = new RoutingDataSourceContext(key); return joinPoint.proceed(); }}

改造Controller方法

@RoutingWith('masterDataSource') @GetMapping('/findAllProductM') public String findAllProductM() { productService.findAllProductM(); return 'lagou'; }@RoutingWith('slaveDataSource') @GetMapping('/findAllProductS') public String findAllProductS() { productService.findAllProductS(); return 'lagou'; }

到此這篇關(guān)于詳解SpringBoot+Mybatis實(shí)現(xiàn)動(dòng)態(tài)數(shù)據(jù)源切換的文章就介紹到這了,更多相關(guān)SpringBoot+Mybatis動(dòng)態(tài)數(shù)據(jù)源切換內(nèi)容請搜索好吧啦網(wǎng)以前的文章或繼續(xù)瀏覽下面的相關(guān)文章希望大家以后多多支持好吧啦網(wǎng)！