史上最简单的spring boot和mybatis结合的多数据源配置
本文将介绍使用Spring Boot集成Mybatis并实现主从库分离的实现（适用于多数据源），网上有很多讲述多数据源的，有的太复杂，有的不生效，我下面的是直接可以用的，而且是最简单的，这里写出来，和大家共同学习，如有不对，请指出来，感谢，本人企鹅：761173739，废话少说，直接来：
1.pom的依赖，这里太多，后期我再整理一个最简洁的：
com.sunny.study
multiple-datasource
0.0.1-SNAPSHOT
jar
springboot-multiple-datasource
多数据源
org.springframework.boot
spring-boot-starter-parent
2.0.3.RELEASE
UTF-8
UTF-8
1.8
org.springframework.boot
spring-boot-starter-aop
org.springframework.boot
spring-boot-starter-web
org.springframework.boot
spring-boot-starter-tomcat
org.springframework.boot
spring-boot-starter-undertow
org.mybatis.spring.boot
mybatis-spring-boot-starter
1.3.2
com.github.pagehelper
pagehelper-spring-boot-starter
1.2.4
org.springframework.boot
spring-boot-starter-test
test
org.apache.commons
commons-lang3
com.alibaba
druid
1.0.13
mysql
mysql-connector-java
org.springframework.boot
spring-boot-configuration-processor
true
注意：项目是通过扩展mybatis-spring-boot-starter的org.mybatis.spring.boot.autoconfigure.MybatisAutoConfiguration来实现多数据源注入的，这也是最简洁的方式
2.application.yml：
# 数据库访问配置
# 使用druid数据源
druid:
type: com.alibaba.druid.pool.DruidDataSource
master:
url: jdbc:mysql://127.0.0.1:3306/test_db?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&zeroDateTimeBehavior=convertToNull&useUnicode=true&useSSL=false
username: root
password: root
driver-class-name: com.mysql.jdbc.Driver
filters: stat
maxActive: 20
initialSize: 3
maxWait: 60000
minIdle: 3
timeBetweenEvictionRunsMillis: 60000
minEvictableIdleTimeMillis: 300000
validationQuery: select 'x'
testWhileIdle: true
testOnBorrow: false
testOnReturn: false
poolPreparedStatements: true
maxOpenPreparedStatements: 20
slave:
url: jdbc:mysql://127.0.0.1:3306/test_db2?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&zeroDateTimeBehavior=convertToNull&useUnicode=true&useSSL=false
username: root
password: root
driver-class-name: com.mysql.jdbc.Driver
filters: stat
maxActive: 20
initialSize: 3
maxWait: 60000
minIdle: 3
timeBetweenEvictionRunsMillis: 60000
minEvictableIdleTimeMillis: 300000
validationQuery: select 'x'
testWhileIdle: true
testOnBorrow: false
testOnReturn: false
poolPreparedStatements: true
maxOpenPreparedStatements: 203.创建数据源：
@Configuration
@EnableTransactionManagement
public class DataSourceConfiguration {
@Value("${druid.type}")
private Class dataSourceType;
@Bean(name="masterDataSource")
@Primary
@ConfigurationProperties(prefix = "druid.master")
public DataSource masterDataSource() {
return DataSourceBuilder.create().type(dataSourceType).build();
}
@Bean(name = "slaveDataSource")
@ConfigurationProperties(prefix = "druid.slave")
public DataSource slaveDataSource() {
return DataSourceBuilder.create().type(dataSourceType).build();
}
}
4.将多数据源注入到sqlSessionFactory中：
切记注意：请看代码中的注释，否则不生效4.1以下是mybatis-spring-boot-starter1.1.1版本的配置
@Configuration
@AutoConfigureAfter({DataSourceConfiguration.class})
public class MybatisConfiguration extends MybatisAutoConfiguration {
public MybatisConfiguration(MybatisProperties properties, ObjectProvider interceptorsProvider,
ResourceLoader resourceLoader, ObjectProvider databaseIdProvider,
ObjectProvider> configurationCustomizersProvider) {
super(properties, interceptorsProvider, resourceLoader, databaseIdProvider, configurationCustomizersProvider);
}
private static Log logger = LogFactory.getLog(MybatisConfiguration.class);
@Resource(name = "masterDataSource")
private DataSource masterDataSource;
@Resource(name = "slaveDataSource")
private DataSource slaveDataSource;
@Bean
public SqlSessionFactory sqlSessionFactory() throws Exception {
logger.info("-------------------- 重载父类 sqlSessionFactory init ---------------------");
return super.sqlSessionFactory(roundRobinDataSouceProxy());
}
public AbstractRoutingDataSource roundRobinDataSouceProxy(){
DbRouteDataSource proxy = new DbRouteDataSource();
@SuppressWarnings("unchecked")
Map targetDataResources = new ClassLoaderRepository.SoftHashMap();
targetDataResources.put(DbContextHolder.DbType.MASTER,masterDataSource);
targetDataResources.put(DbContextHolder.DbType.SLAVE,slaveDataSource);
proxy.setDefaultTargetDataSource(masterDataSource);
proxy.setTargetDataSources(targetDataResources);
return proxy;
}
}
4.2以下是mybatis-spring-boot-starter1.3版本的配置，红色地方需要注意
@Configuration
@AutoConfigureAfter({DataSourceConfiguration.class})
public class MybatisConfiguration extends MybatisAutoConfiguration {
public MybatisConfiguration(MybatisProperties properties, ObjectProvider interceptorsProvider,
ResourceLoader resourceLoader, ObjectProvider databaseIdProvider,
ObjectProvider> configurationCustomizersProvider) {
super(properties, interceptorsProvider, resourceLoader, databaseIdProvider, configurationCustomizersProvider);
}
private static Log logger = LogFactory.getLog(MybatisConfiguration.class);
@Resource(name = "masterDataSource")
private DataSource masterDataSource;
@Resource(name = "slaveDataSource")
private DataSource slaveDataSource;
@Bean
@Override
public SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception {
logger.info("-------------------- 重载父类 sqlSessionFactory init ---------------------");
return super.sqlSessionFactory(roundRobinDataSouceProxy());
}
public AbstractRoutingDataSource roundRobinDataSouceProxy(){
DbRouteDataSource proxy = new DbRouteDataSource();
Map targetDataResources = new HashMap(2);
targetDataResources.put(DbContextHolder.DbType.MASTER,masterDataSource);
targetDataResources.put(DbContextHolder.DbType.SLAVE,slaveDataSource);
proxy.setDefaultTargetDataSource(masterDataSource);
proxy.setTargetDataSources(targetDataResources);
proxy.afterPropertiesSet();
return proxy;
}
} 5.实现读写分离（多数据源分离）：
这里主要思路如下：
1-将不同的数据源标识记录在ThreadLocal中
2-通过注解标识出当前的service方法使用哪个库
3-通过Spring AOP实现拦截注解并注入不同的标识到threadlocal中
4-获取源的时候通过threadlocal中不同的标识给出不同的sqlSession
1-将不同的数据源标识记录在ThreadLocal中
2-通过注解标识出当前的service方法使用哪个库
3-通过Spring AOP实现拦截注解并注入不同的标识到threadlocal中
4-获取源的时候通过threadlocal中不同的标识给出不同的sqlSession
标识存放ThreadLocal的实现
public class DbContextHolder {
public enum DbType{
/***
* 主数据源
*/
MASTER,
/***
* 从数据源
*/
SLAVE
}
private static final ThreadLocal CONTEXT_HOLDER = new ThreadLocal<>();
public static void setDbType(DbType dbType){
if(dbType==null){
throw new NullPointerException();
}else{
CONTEXT_HOLDER.set(dbType);
}
}
public static DbType getDbType(){
return CONTEXT_HOLDER.get()==null? DbType.MASTER:CONTEXT_HOLDER.get();
}
public static void clearDbType() {
CONTEXT_HOLDER.remove();
}
} 注解实现
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface SlaveDataSource {
}Spring AOP对注解的拦截
@Aspect
@Component
public class SlaveDataSourceInterceptor implements Ordered {
public static final Logger logger = LoggerFactory.getLogger(SlaveDataSourceInterceptor.class);
@Around("@annotation(slaveDataSource)")
public Object proceed(ProceedingJoinPoint proceedingJoinPoint, SlaveDataSource slaveDataSource) throws Throwable {
try {
logger.debug("set database connection to read only");
DbContextHolder.setDbType(DbContextHolder.DbType.SLAVE);
Object result = proceedingJoinPoint.proceed();
return result;
}finally {
DbContextHolder.clearDbType();
logger.debug("restore database connection");
}
}
@Override
public int getOrder() {
return 0;
}
}使用方式：
@SlaveDataSource
@RequestMapping(value = "/abc/xxx", method = RequestMethod.POST)
public Object queryList(@RequestBody Object vo) throws BaseException {
return "ok";
}