springboot+mysql讀寫分離
阿新 • • 發佈：2021-01-14
在javaweb開發中資料庫表資料量會越來越大，為了減輕資料庫讀寫壓力，對資料庫進行主從模式部署（一主一從，多主多從），在應用層面可以通過spring提供的路由資料來源+註解+切面進行控制，在程式碼層面切換不同資料庫源，不同操作選擇不同資料庫。
程式碼如下：
<dependency> <groupId>com.alibaba</groupId> <artifactId>druid-spring-boot-starter</artifactId> <version>1.1.9</version> </dependency> <!-- 引入mybatis 依賴--> <dependency> <groupId>org.mybatis.spring.boot</groupId> <artifactId>mybatis-spring-boot-starter</artifactId> <version>1.1.1</version> </dependency> <!-- mysql 依賴--> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <!--<scope>runtime</scope>--> </dependency>
spring.datasource.master.url=jdbc:mysql://localhost:3306/master?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8&useSSL=false spring.datasource.master.username=root spring.datasource.master.password=123456 spring.datasource.master.driver-class-name=com.mysql.cj.jdbc.Driver spring.datasource.slave.url=jdbc:mysql://localhost:3306/slave?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8&useSSL=false spring.datasource.slave.username=root spring.datasource.slave.password=123456 spring.datasource.slave.driver-class-name=com.mysql.cj.jdbc.Driver
@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class, TransactionAutoConfiguration.class}) @MapperScan("com.*.mapper") public class AnnotationAopReflectionApplication { public static void main(String[] args) { SpringApplication.run(AnnotationAopReflectionApplication.class, args); } }
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
@Documented
public @interface DataSourceAnnotation {
/**
* 預設資料來源
*/
DataSourceEnum value() default DataSourceEnum.MASTER;
/**
* 清除
*/
boolean clear() default true;
}
public enum DataSourceEnum {
//資料來源主庫、從庫
MASTER("1","master"),
SLAVE("2","slave");
private String code;
private String name;
private DataSourceEnum(String code,String name){
this.code = code;
this.name = name;
}
public static DataSourceEnum getByCode(String code) {
for (DataSourceEnum event : DataSourceEnum.values()) {
if (event.code.equals(code)) {
return event;
}
}
return null;
}
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
public class DataSourceContextHolder {
private static final ThreadLocal<String> context = new ThreadLocal<>();
/**
* 賦值
*/
public static void set(String datasourceType) {
context.set(datasourceType);
}
/**
* 獲取值
*/
public static String get() {
return context.get();
}
/**
* 清空
*/
public static void clear() {
context.remove();
}
}
public class RoutingDataSource extends AbstractRoutingDataSource {
/**
* 最終的determineCurrentLookupKey返回的是從DataSourceContextHolder中拿到的,因此在動態切換資料來源的時候註解
* 應該給DataSourceContextHolder設值
*/
@Override
protected Object determineCurrentLookupKey() {
return DataSourceContextHolder.get();
}
}
@Configuration
@MapperScan(basePackages = "com.", sqlSessionTemplateRef = "sqlSessionTemplate")
public class DataSourceConfig {
/**
* 主庫
*/
@Bean
@ConfigurationProperties(prefix = "spring.datasource.master")
public DataSource master() {
return DruidDataSourceBuilder.create().build();
}
/**
* 從庫
*/
@Bean
@ConfigurationProperties(prefix = "spring.datasource.slave")
public DataSource slaver() {
return DruidDataSourceBuilder.create().build();
}
/**
* 例項化資料來源路由
*/
@Bean
public RoutingDataSource routingDataSource(@Qualifier("master") DataSource masterDataSource,@Autowired(required = false) @Qualifier("slaver") DataSource slaveDataSource) {
RoutingDataSource routingDataSource = new RoutingDataSource();
Map<Object, Object> targetDataSources = new HashMap<>();
targetDataSources.put(DataSourceEnum.MASTER.getName(), masterDataSource);
if (slaveDataSource != null) {
targetDataSources.put(DataSourceEnum.SLAVE.getName(), slaveDataSource);
}
routingDataSource.setTargetDataSources(targetDataSources);
routingDataSource.setDefaultTargetDataSource(masterDataSource);
return routingDataSource;
}
/**
* 配置sessionFactory
*/
@Bean
public SqlSessionFactory sqlSessionFactory(@Qualifier("routingDataSource") DataSource routingDataSource) throws Exception {
SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources("classpath*:mapper/*.xml"));
sqlSessionFactoryBean.setDataSource(routingDataSource);
return sqlSessionFactoryBean.getObject();
}
/**
* 建立sqlSessionTemplate
*/
@Bean
public SqlSessionTemplate sqlSessionTemplate(@Qualifier("sqlSessionFactory") SqlSessionFactory sqlSessionFactory) {
return new SqlSessionTemplate(sqlSessionFactory);
}
/**
* 事務配置
*/
@Bean(name = "dataSourceTransactionManager")
public DataSourceTransactionManager dataSourceTransactionManager(@Qualifier("routingDataSource") DataSource dynamicDataSource) {
DataSourceTransactionManager dataSourceTransactionManager = new DataSourceTransactionManager();
dataSourceTransactionManager.setDataSource(dynamicDataSource);
return dataSourceTransactionManager;
}
}
@Aspect
@Order(value = 1)
@Component
public class DataSourceAspect {
@Around("@annotation(com.*.DataSourceAnnotation)")
public Object setDynamicDataSource(ProceedingJoinPoint pjp) throws Throwable {
boolean clear = false;
try {
Method method = this.getMethod(pjp);
DataSourceAnnotation dataSourceAnnotation = method.getAnnotation(DataSourceAnnotation.class);
clear = dataSourceAnnotation.clear();
DataSourceContextHolder.set(dataSourceAnnotation.value().getName());
System.out.println(String.format("資料來源切換至：{%s}", dataSourceAnnotation.value().getName()));
return pjp.proceed();
} finally {
if (clear) {
DataSourceContextHolder.clear();
}
}
}
private Method getMethod(JoinPoint pjp) {
MethodSignature signature = (MethodSignature) pjp.getSignature();
return signature.getMethod();
}
}
@Service
public class DemoService {
@Autowired
private UserMapper userMapper;
@Autowired
private AuthUserMapper authUserMapper;
/**
* 讀操作
*/
@DataSourceAnnotation(DataSourceEnum.SLAVE)
public AuthUser getAuthUser() {
String userId = "001";
AuthUser authUser = authUserMapper.getAuthUserById(userId);
//User user = userMapper.getUserById(1);
return authUser;
}
/**
* 寫操作
*/
@DataSourceAnnotation(DataSourceEnum.MASTER)
public User updateUser() {
User user = userMapper.getUserById(1);
return user;
}
}
@RestController
public class DemoController {
@Autowired
private DemoService demoService;
@GetMapping("/readSlave")
public Object readSlave() {
return demoService.getAuthUser();
}
@GetMapping("/writeMaster")
public Object writeMaster() {
return demoService.updateUser();
}
}
前提是部署好mysql主從資料庫或準備不同資料庫。注意讀寫分離的核心點就是資料路由，需要繼承AbstractRountingDataSource，覆寫它的determinCurrentLookupKey方法，同時需要注意全域性的上下文管理器DataSourceContextHolder，它是儲存資料來源上下文的主要類，也是路由方法中尋找的資料來源取值，相當於資料來源的中轉站，此例配置了3個數據源。再結合jdbc底層、事務等，資料庫讀寫分離就實現了。