1. 引入mybatis-plus相關包，pom.xml文件

2. 配置文件application.property增加多庫配置

mysql 數(shù)據(jù)源配置

spring.datasource.primary.jdbc-url=jdbc:mysql://xx.xx.xx.xx:3306/portal?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC&characterEncoding=utf8&serverTimezone=GMT%2B8spring.datasource.primary.username=rootspring.datasource.primary.password=rootspring.datasource.primary.driver-class-name=com.mysql.cj.jdbc.Driver#mysql slave 數(shù)據(jù)源配置spring.datasource.slave.jdbc-url=jdbc:mysql://xx.xx.xx.xx:3306/portal?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC&characterEncoding=utf8&serverTimezone=GMT%2B8spring.datasource.slave.username=rootspring.datasource.slave.password=rootspring.datasource.slave.driver-class-name=com.mysql.cj.jdbc.Driver

3. 配置數(shù)據(jù)源及注解

數(shù)據(jù)源配置 MultiDataSourceConfig.Java

/** * 配置多數(shù)據(jù)源 */@Profile('dev')//開發(fā)模式配置文件@Configuration@MapperScan(basePackages = 'com.csc.portal.mapper')//掃描包public class MultiDataSourceConfig { /** * 主數(shù)據(jù)源 * @return */ @Bean @ConfigurationProperties(prefix = 'spring.datasource.primary') public DataSource masterDataSource() { return DataSourceBuilder.create().build(); } /** * 從數(shù)據(jù)源 * @return */ @Bean @ConfigurationProperties(prefix = 'spring.datasource.slave') public DataSource slaveDataSource() { return DataSourceBuilder.create().build(); } /** * 路由數(shù)據(jù)源，前面兩個數(shù)據(jù)源是為了創(chuàng)建此數(shù)據(jù)源 * @param masterDataSource 主數(shù)據(jù)源 * @param slaveDataSource 從數(shù)據(jù)源 * @return */ @Bean public DataSource myRoutingDataSource(@Qualifier('masterDataSource') DataSource masterDataSource, @Qualifier('slaveDataSource') DataSource slaveDataSource) { Map<Object, Object> targetDataSources = new HashMap<>(); targetDataSources.put(DBTypeEnum.MASTER, masterDataSource); targetDataSources.put(DBTypeEnum.SLAVE, slaveDataSource); MyRoutingDataSource myRoutingDataSource = new MyRoutingDataSource(); myRoutingDataSource.setDefaultTargetDataSource(slaveDataSource);//設置默認數(shù)據(jù)源 myRoutingDataSource.setTargetDataSources(targetDataSources);//設置路由表，使用map的key，value方式得到對應數(shù)據(jù)源 return myRoutingDataSource; }

數(shù)據(jù)庫枚舉類

public enum DBTypeEnum { MASTER, SLAVE;}

注解

@Target({ElementType.METHOD})@Retention(RetentionPolicy.RUNTIME)public @interface Master {}

@Target({ElementType.METHOD})@Retention(RetentionPolicy.RUNTIME)public @interface Slave {}

4. Mybatis-plus配置

@EnableTransactionManagement@Configuration@MapperScan(basePackages = 'com.csc.portal.mapper')public class MybatisPlusConfig { /** * 分頁插件 */ @Bean public PaginationInterceptor paginationInterceptor() { return new PaginationInterceptor(); } @Resource(name = 'myRoutingDataSource') private DataSource myRoutingDataSource; /** * 使用MyBatis Plus的sqlSessionFactory代替， * 此處注意mybatis與mybatisPlus的配置不同，不然掃描不到對數(shù)據(jù)操作的方法。會報未綁定錯誤 * @return sqlSessionFactory * @throws Exception */ @Bean public SqlSessionFactory sqlSessionFactory() throws Exception { MybatisSqlSessionFactoryBean sqlSessionFactoryBean = new MybatisSqlSessionFactoryBean(); sqlSessionFactoryBean.setDataSource(myRoutingDataSource); sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources('classpath:mapper/*.xml')); MybatisConfiguration mybatisConfiguration = new MybatisConfiguration(); sqlSessionFactoryBean.setConfiguration(mybatisConfiguration); return sqlSessionFactoryBean.getObject(); } /** * 此處為使用mybatis時的sqlsessionFactory配置 * @return * @throws Exception */ /* @Bean public SqlSessionFactory sqlSessionFactory() throws Exception { SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean(); sqlSessionFactoryBean.setDataSource(myRoutingDataSource); sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources('classpath:mapper/*.xml')); return sqlSessionFactoryBean.getObject(); } */ /** * 事務配置 * @return 事務管理器 */ @Bean public DataSourceTransactionManager transactionManager() { DataSourceTransactionManager tx = new DataSourceTransactionManager(); tx.setDataSource(myRoutingDataSource); return tx; }

5. 增加數(shù)據(jù)源管理類

DBContextHolder.java

public class DBContextHolder { /** * 外部一個請求將會產生一個線程與之對應，每個線程的變量可用ThreadLocal進行存儲 */ private static final ThreadLocal<DBTypeEnum> contextHolder = new ThreadLocal<>(); public static void set(DBTypeEnum dbType) { contextHolder.set(dbType); } public static DBTypeEnum get() { return contextHolder.get(); } public static void master() { set(DBTypeEnum.MASTER); System.out.println('切換到master'); } public static void slave() { set(DBTypeEnum.SLAVE); System.out.println('切換到slave'); }}

指定選擇數(shù)據(jù)源

MyRoutingDataSource.java 方法determineCurrentLookupKey決定最終使用哪個數(shù)據(jù)源進行操作，若為空則使用默認數(shù)據(jù)源。

public class MyRoutingDataSource extends AbstractRoutingDataSource { @Nullable @Override protected Object determineCurrentLookupKey() { System.out.println('線程名：'+Thread.currentThread().getName()+':'+DBContextHolder.get()); return DBContextHolder.get();/* if (DBContextHolder.get() != null) { System.out.println('線程名：'+Thread.currentThread().getName()+':'+DBContextHolder.get()); return DBContextHolder.get(); } else { System.out.println('未匹配到指定數(shù)據(jù)庫,默認切換到Master'); return DBTypeEnum.MASTER; }*/ //return DBContextHolder.get(); }}

6. 增加aop切面

@Aspect@Component@Order(0)//配置注解優(yōu)先級，優(yōu)于事物注解@Transactional先進行數(shù)據(jù)源切換，//不然在事物中進行數(shù)據(jù)源切換無效public class DataSourceAop { @Pointcut(/*'!@annotation(com.csc.portal.annotation.Master) ' + '&& (execution(* com.csc.portal.service..*.select*(..)) ' + '|| execution(* com.csc.portal.service..*.get*(..))'+*/ ' @annotation(com.csc.portal.annotation.Slave)') public void readPointcut() { } @Pointcut('@annotation(com.csc.portal.annotation.Master) ' //+ /* '|| execution(* com.csc.portal.service..*.insert*(..)) ' + '|| execution(* com.csc.portal.service..*.add*(..)) ' + '|| execution(* com.csc.portal.service..*.update*(..)) ' + '|| execution(* com.csc.portal.service..*.edit*(..)) ' + '|| execution(* com.csc.portal.service..*.delete*(..)) ' + '|| execution(* com.csc.portal.service..*.remove*(..))'*/) public void writePointcut() { } @Before('readPointcut()') public void read() { //獲取攔截類 DBContextHolder.slave(); System.out.println(Thread.currentThread().getName()+DBContextHolder.get()); } @Before('writePointcut()') public void write() { //獲取攔截類/* String className = pjp.getTarget().getClass().getName(); System.out.println('當前線程'+Thread.currentThread().getName()+' 攔截類為：' + className); //獲取攔截的方法名 MethodSignature msig = (MethodSignature) pjp.getSignature(); Method currentMethod = null; try { currentMethod = pjp.getTarget().getClass().getMethod(msig.getName(), msig.getParameterTypes()); } catch (NoSuchMethodException e) { e.printStackTrace(); } String methodName = currentMethod.getName(); System.out.println('攔截方法名為：' + methodName);*/ DBContextHolder.master(); System.out.println(Thread.currentThread().getName()+DBContextHolder.get()); } }

6. 實際應用

在service層方法前增加注解@Master表示使用主庫，進行增刪改的操作使用主庫。 在service層方法前增加注解@Slave表示使用從庫，進行查的操作使用從庫，默認使用從庫，可不配置。 @ Transactional注解加到service層，增加了@Transactional注解后，啟用事務后，一個事務內部的connection是復用的，所以就算AOP切了數(shù)據(jù)源字符串，但是數(shù)據(jù)源并不會被真正修改。所以@Transactional注解不要寫在controller層，不然在service層也切換不了數(shù)據(jù)源。 @Transactional與@Master可同時使用，已經(jīng)配置@Master注解的優(yōu)先級較高，先切換數(shù)據(jù)源后執(zhí)行事務。

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