帶你了解mybatis如何實(shí)現(xiàn)讀寫分離
首先application-test.yml增加如下數(shù)據(jù)源的配置
spring: datasource: master: jdbc-url: jdbc:mysql://master域名:3306/test username: root password: 123456 driver-class-name: com.mysql.jdbc.Driver slave1: jdbc-url: jdbc:mysql://slave域名:3306/test username: root # 只讀賬戶 password: 123456 driver-class-name: com.mysql.jdbc.Driver slave2: jdbc-url: jdbc:mysql://slave域名:3306/test username: root # 只讀賬戶 password: 123456 driver-class-name: com.mysql.jdbc.Driver
package com.cjs.example.enums;public enum DBTypeEnum { MASTER, SLAVE1, SLAVE2;}
定義ThreadLocal上下文,將當(dāng)前線程的數(shù)據(jù)源進(jìn)行動(dòng)態(tài)修改
public class DBContextHolder { private static volatile ThreadLocal<DBTypeEnum> contextHolder = new ThreadLocal<>(); public static synchronized void set(DBTypeEnum dbType) {contextHolder.set(dbType); } public static synchronized DBTypeEnum get() {return contextHolder.get(); } public static void master() {set(DBTypeEnum.MASTER); } public static void slave() {set(DBTypeEnum.SLAVE1); } public static void slave2(){ set(DBTypeEnum.SLAVE2); } // 清除數(shù)據(jù)源名 public static void clearDB() {contextHolder.remove(); }}
重寫mybatis數(shù)據(jù)源路由接口,在此修改數(shù)據(jù)源為我們上一塊代碼設(shè)置的上下文的數(shù)據(jù)源
public class MyRoutingDataSource extends AbstractRoutingDataSource { @Nullable @Override protected Object determineCurrentLookupKey() {DBTypeEnum dbTypeEnum=DBContextHolder.get();return dbTypeEnum; }}
將yml配置的多數(shù)據(jù)源手動(dòng)指定注入
@Configurationpublic class DataSourceConfig { @Bean @ConfigurationProperties('spring.datasource.master') public DataSource masterDataSource() {return DataSourceBuilder.create().build(); } @Bean @ConfigurationProperties('spring.datasource.slave1') public DataSource slave1DataSource() {return DataSourceBuilder.create().build(); } @Bean public DataSource myRoutingDataSource(@Qualifier('masterDataSource') DataSource masterDataSource, @Qualifier('slave1DataSource') DataSource slave1DataSource) {Map<Object, Object> targetDataSources = new HashMap<>();targetDataSources.put(DBTypeEnum.MASTER, masterDataSource);targetDataSources.put(DBTypeEnum.SLAVE1, slave1DataSource);MyRoutingDataSource myRoutingDataSource = new MyRoutingDataSource();myRoutingDataSource.setDefaultTargetDataSource(masterDataSource);myRoutingDataSource.setTargetDataSources(targetDataSources);return myRoutingDataSource; }}
sqlsession注入以上我們配置的datasource路由
@EnableTransactionManagement@Configuration@Import({TableSegInterceptor.class})public class MyBatisConfig { @Resource(name = 'myRoutingDataSource') private DataSource myRoutingDataSource; @Autowired private MybatisConfigProperty mybatisConfigProperty; @Autowired private TableSegInterceptor tableSegInterceptor; @Bean public SqlSessionFactory sqlSessionFactory() throws Exception {SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();sqlSessionFactoryBean.setDataSource(myRoutingDataSource);// SpringBoot項(xiàng)目集成mybatis打包為jar運(yùn)行時(shí)setTypeAliasesPackage無(wú)效解決VFS.addImplClass(SpringBootVFS.class);sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources(mybatisConfigProperty.getMapperLocations()));sqlSessionFactoryBean.setTypeAliasesPackage(mybatisConfigProperty.getTypeAliasesPackage());sqlSessionFactoryBean.setConfigLocation(new PathMatchingResourcePatternResolver().getResource(mybatisConfigProperty.getConfigLocation()));sqlSessionFactoryBean.setPlugins(new Interceptor[]{tableSegInterceptor});return sqlSessionFactoryBean.getObject(); } @Bean public PlatformTransactionManager platformTransactionManager() {return new DataSourceTransactionManager(myRoutingDataSource); }}
spring aop攔截指定前綴的service方法,并設(shè)置對(duì)應(yīng)所屬的上下文
@Aspect@Componentpublic class DataSourceAop { @Pointcut('!@annotation(com.ask.student.interceptor.annotation.Master) ' + '&& (execution(* com.ask.student.service..*.select*(..)) ' + '|| execution(* com.ask.student.service..*.get*(..))' + '|| execution(* com.ask.student.service..*.find*(..))' + ')') public void readPointcut() { } @Pointcut('@annotation(com.ask.student.interceptor.annotation.Master) ' + '|| execution(* com.ask.student.service..*.insert*(..)) ' + '|| execution(* com.ask.student.service..*.clean*(..)) ' + '|| execution(* com.ask.student.service..*.reset*(..)) ' + '|| execution(* com.ask.student.service..*.add*(..)) ' + '|| execution(* com.ask.student.service..*.update*(..)) ' + '|| execution(* com.ask.student.service..*.edit*(..)) ' + '|| execution(* com.ask.student.service..*.delete*(..)) ' + '|| execution(* com.ask.student.service..*.remove*(..))') public void writePointcut() { } @Before('readPointcut()') public void read() {DBContextHolder.slave(); } @Before('writePointcut()') public void write() {DBContextHolder.master(); } @After('readPointcut()||writePointcut()') public void afterSwitchDS(){DBContextHolder.clearDB(); }}
以上最后一個(gè)方法的作用,在攔截器中獲取后及時(shí)清除避免導(dǎo)致來(lái)回切換當(dāng)前線程變量延遲問(wèn)題導(dǎo)致某些操作的數(shù)據(jù)源錯(cuò)誤
DBContextHolder.clearDB();
@After('readPointcut()||writePointcut()')
public void afterSwitchDS(){
DBContextHolder.clearDB();
}
2、mybatis-plus的實(shí)現(xiàn)方式這個(gè)方式配置簡(jiǎn)單,代碼少,很多事情mybatis-plus都已經(jīng)做好了,推薦使用
yml配置如下
datasource: dynamic: primary: master #設(shè)置默認(rèn)的數(shù)據(jù)源或者數(shù)據(jù)源組,默認(rèn)值即為master strict: false #設(shè)置嚴(yán)格模式,默認(rèn)false不啟動(dòng). 啟動(dòng)后在未匹配到指定數(shù)據(jù)源時(shí)候會(huì)拋出異常,不啟動(dòng)則使用默認(rèn)數(shù)據(jù)源. datasource:master: url: jdbc:mysql://xxx:3306/db0?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&useSSL=false&zeroDateTimeBehavior=convertToNull&serverTimezone=Asia/Shanghai username: admin password: 123456 driver-class-name: com.mysql.cj.jdbc.Driver type: com.zaxxer.hikari.HikariDataSource hikari: minimum-idle: 5 maximum-pool-size: 15 auto-commit: true idle-timeout: 30000 pool-name: springHikariCP max-lifetime: 1800000 connection-timeout: 30000 connection-test-query: SELECT 1slave1: url: jdbc:mysql://xxx:3306/db2?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&useSSL=false&zeroDateTimeBehavior=convertToNull&serverTimezone=Asia/Shanghai username: admin password: 123456 driver-class-name: com.mysql.cj.jdbc.Driver type: com.zaxxer.hikari.HikariDataSource hikari: minimum-idle: 5 maximum-pool-size: 15 auto-commit: true idle-timeout: 30000 pool-name: springHikariCP max-lifetime: 1800000 connection-timeout: 30000 connection-test-query: SELECT 1slave2: url: jdbc:mysql://xxx:3306/db3?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&useSSL=false&zeroDateTimeBehavior=convertToNull&serverTimezone=Asia/Shanghai username: admin password: 123456 driver-class-name: com.mysql.cj.jdbc.Driver type: com.zaxxer.hikari.HikariDataSource hikari: minimum-idle: 5 maximum-pool-size: 15 auto-commit: true idle-timeout: 30000 pool-name: springHikariCP max-lifetime: 1800000 connection-timeout: 30000 connection-test-query: SELECT 1
使用起來(lái)非常簡(jiǎn)單,只需要加上這個(gè)master的注解即可
@Override @DS('master') public DestMedia getOneByCodeFromEpg(String code) {QueryWrapper queryWrapper = new QueryWrapper();queryWrapper.eq('code', code);return super.getOne(queryWrapper); }總結(jié)
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