1 背景
springboot配置mybatisPlus，mybatisPlus配置一主二从数据源。
数据源切换，通过mybatis的拦截器结合本地线程变量，自动切换数据源。
切换原则：不在事务中的查询，使用从库，其他情况均使用主库
流程图：
mybatisPlus自动切换数据源.jpg
2 版本
- JDK：
1.8 - mysql：
5.6 - springboot：
2.2.9.RELEASE - mybatis-plus：
3.4.0
3 配置
路径说明：
| 用途 | 路径 |
|---|---|
| bean | com.sa.example.mybatis2.ext.bean |
| mapper | com.sa.example.mybatis2.ext.mapper；com.sa.example.mybatis2.auto.mapper |
| xml | com.sa.example.mybatis2.ext.mapper.xml；com.sa.example.mybatis2.auto.mapper.xml |
| bean配置 | com.sa.example.mybatis2.config |
3.1 pom配置
3.1.1 父类pom
org.springframework.boot
spring-boot-starter-parent
2.2.9.RELEASE
3.1.2 pom依赖
mysql
mysql-connector-java
5.1.30
com.alibaba
druid
1.1.23
org.mybatis.spring.boot
mybatis-spring-boot-starter
2.1.3
com.baomidou
mybatis-plus-boot-starter
3.4.0
org.springframework.boot
spring-boot-starter-web
org.springframework.boot
spring-boot-starter-test
test
org.projectlombok
lombok
1.18.12
provided
org.apache.commons
commons-lang3
3.11
3.1.3 插件
保证可以在src的包里配置mapper的xml文件，否则需要再resource文件夹中配置mapper的xml。
org.springframework.boot
spring-boot-maven-plugin
src/main/java
**/*.*
src/main/resources
**/**
3.2 application.yml配置
#==========自定义mybatisPlus数据源==========
datasource:
#数据源类型
type: com.alibaba.druid.pool.DruidDataSource
#从库节点数量
slaveNodeCount: 2
#主库
master:
driver-class-name: com.mysql.jdbc.Driver
url: jdbc:mysql://127.0.0.1:3306/test01?useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=round&useAffectedRows=true
username: root
password: root
pool-config:
initialSize: 100
minIdle: 1
maxActive: 50
maxWait: 60000
timeBetweenEvictionRunsMillis: 60000
minEvictableIdleTimeMillis: 300000
validationQuery: SELECT 'x'
testWhileIdle: true
testOnBorrow: false
testOnReturn: false
poolPreparedStatements: false
maxPoolPreparedStatementPerConnectionSize: -1
filters: stat,logback
#从库1
slave1:
driver-class-name: com.mysql.jdbc.Driver
url: jdbc:mysql://127.0.0.1:3306/test02?useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=round&useAffectedRows=true
username: root
password: root
pool-config:
initialSize: 100
minIdle: 1
maxActive: 50
maxWait: 60000
timeBetweenEvictionRunsMillis: 60000
minEvictableIdleTimeMillis: 300000
validationQuery: SELECT 'x'
testWhileIdle: true
testOnBorrow: false
testOnReturn: false
poolPreparedStatements: false
maxPoolPreparedStatementPerConnectionSize: -1
filters: stat,logback
#从库2
slave2:
driver-class-name: com.mysql.jdbc.Driver
url: jdbc:mysql://127.0.0.1:3306/test03?useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=round&useAffectedRows=true
username: root
password: root
pool-config:
initialSize: 100
minIdle: 1
maxActive: 50
maxWait: 60000
timeBetweenEvictionRunsMillis: 60000
minEvictableIdleTimeMillis: 300000
validationQuery: SELECT 'x'
testWhileIdle: true
testOnBorrow: false
testOnReturn: false
poolPreparedStatements: false
maxPoolPreparedStatementPerConnectionSize: -1
filters: stat,logback
#==========整合mybatisPlus==========
mybatis-plus:
type-aliases-package: com.lx.ms.db.mybatis.bean.ext
mapper-locations: classpath:com/sa/example/mybatis2/ext/mapper/xml/*.xml,classpath:com/sa/example/mybatis2/auto/mapper/xml/*.xml
configuration:
map-underscore-to-camel-case: true
cache-enabled: true
lazy-loading-enabled: false
aggressive-lazy-loading: true
log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
3.3 bean配置
mybatisPlus配置bean所在包：com.sa.example.mybatis2.config
3.3.1 数据源配置信息
/**
* 数据源配置信息
*/
@Configuration
public class DataSourcePropertiesConfig {
/**
* 主库配置
* @return 数据源配置
*/
@Primary
@Bean
@ConfigurationProperties("datasource.master")
public DataSourceProperties masterDataSourceProperties() {
return new DataSourceProperties();
}
/**
* 从库配置
* @return 数据源配置
*/
@Bean
@ConfigurationProperties("datasource.slave1")
public DataSourceProperties slave1DataSourceProperties() {
return new DataSourceProperties();
}
/**
* 从库配置
* @return 数据源配置
*/
@Bean
@ConfigurationProperties("datasource.slave2")
public DataSourceProperties slave2DataSourceProperties() {
return new DataSourceProperties();
}
}
3.3.2 数据源配置
/**
* 数据源配置
*/
@Configuration
public class DataSourceConfig {
@Resource
private DataSourceProperties masterDataSourceProperties;
@Resource
private DataSourceProperties slave1DataSourceProperties;
@Resource
private DataSourceProperties slave2DataSourceProperties;
/**
* 数据源类型
*/
@Value("${datasource.type:}")
private Class dataSourceType;
/**
* 如果配置文件未配置，默认取Druid数据源配置
*
* @return
*/
private Class getDataSourceType() {
if (this.dataSourceType == null) {
this.dataSourceType = com.alibaba.druid.pool.DruidDataSource.class;
}
return this.dataSourceType;
}
/**
* 主库数据源
*
* @return
*/
@Bean
@ConfigurationProperties("datasource.master.pool-config")
public DataSource masterDataSource() {
return masterDataSourceProperties.initializeDataSourceBuilder().type(getDataSourceType()).build();
}
/**
* 从库1数据源
*
* @return
*/
@Bean
@ConfigurationProperties("datasource.slave1.pool-config")
public DataSource slave1DataSource() {
return slave1DataSourceProperties.initializeDataSourceBuilder().type(getDataSourceType()).build();
}
/**
* 从库2数据源
*
* @return
*/
@Bean
@ConfigurationProperties("datasource.slave2.pool-config")
public DataSource slave2DataSource() {
return slave2DataSourceProperties.initializeDataSourceBuilder().type(getDataSourceType()).build();
}
}
3.3.3 数据源句柄
/**
* 数据源句柄（存储当前线程中绑定的数据源名称）
*/
class DataSourceHolder {
static final String MASTER_DATASOURCE = "master";
static final String SLAVER1_DATASOURCE = "slaver1";
static final String SLAVER2_DATASOURCE = "slaver2";
/**
* 线程变量（缓存当前数据源名称）
*/
private static final ThreadLocal LOCAL = new ThreadLocal<>();
/**
* 设置数据源
*
* @param dataSource 数据源名称
*/
static void putDataSource(String dataSource) {
LOCAL.set(dataSource);
}
/**
* 获取数据源
*
* @return 数据源名称
*/
static String getDataSource() {
return LOCAL.get();
}
/**
* 清空缓存
*/
static void clearDataSource() {
LOCAL.remove();
}
/**
* 随机获取读库
*
* @return
*/
static String getRandomReadDataSourceName() {
int randomVal = ThreadLocalRandom.current().nextInt(0, 2);
if (randomVal == 0) {
return SLAVER1_DATASOURCE;
} else {
return SLAVER2_DATASOURCE;
}
}
}
3.3.4 动态数据源路由
/**
* 动态数据源路由（对于一次有读有写的事务，事务内的读操作也不应该在slave节点上，所有操作都应该在master节点上）
*/
@Component
public class ExtRoutingDataSource extends AbstractRoutingDataSource {
@Qualifier("masterDataSource")
@Autowired
private DataSource masterDataSource;
@Qualifier("slave1DataSource")
@Autowired
private DataSource slave1DataSource;
@Qualifier("slave2DataSource")
@Autowired
private DataSource slave2DataSource;
@Override
public void afterPropertiesSet() {
//设置默认数据源
this.setDefaultTargetDataSource(masterDataSource);
Map dataSourceMap = new HashMap<>();
dataSourceMap.put(DataSourceHolder.MASTER_DATASOURCE, masterDataSource);
dataSourceMap.put(DataSourceHolder.SLAVER1_DATASOURCE, slave1DataSource);
dataSourceMap.put(DataSourceHolder.SLAVER2_DATASOURCE, slave2DataSource);
//指定目标数据源的映射，并使用查找键作为键
this.setTargetDataSources(dataSourceMap);
super.afterPropertiesSet();
}
@Override
protected Object determineCurrentLookupKey() {
////确定当前查找键
String key = DataSourceHolder.getDataSource();
if (StringUtils.isEmpty(key)) {
//返回默认数据源
return DataSourceHolder.MASTER_DATASOURCE;
}
//读取后，清空内存变量
DataSourceHolder.clearDataSource();
return key;
}
}
3.3.5 重写mybatis自动加载
/**
* 重写mybatis自动加载（重新指定数据源）
*/
@Configuration
public class ExtMybatisPlusAutoConfiguration extends MybatisPlusAutoConfiguration {
@Autowired
private ExtRoutingDataSource extRoutingDataSource;
public ExtMybatisPlusAutoConfiguration(MybatisPlusProperties properties, ObjectProvider interceptorsProvider, ObjectProvider typeHandlersProvider, ObjectProvider languageDriversProvider, ResourceLoader resourceLoader, ObjectProvider databaseIdProvider, ObjectProvider> configurationCustomizersProvider, ObjectProvider> mybatisPlusPropertiesCustomizerProvider, ApplicationContext applicationContext) {
super(properties, interceptorsProvider, typeHandlersProvider, languageDriversProvider, resourceLoader, databaseIdProvider, configurationCustomizersProvider, mybatisPlusPropertiesCustomizerProvider, applicationContext);
}
/**
* 自定义session工厂
*
* @return
* @throws Exception
*/
@Bean
public SqlSessionFactory sqlSessionFactory() throws Exception {
return super.sqlSessionFactory(extRoutingDataSource);
}
/**
* 自定义事务管理器
*
* @return
*/
@Bean
public DataSourceTransactionManager dataSourceTransactionManager() {
return new DataSourceTransactionManager(extRoutingDataSource);
}
}
3.3.6 Mybatis数据源拦截器
/**
* Mybatis数据源拦截器（用户切换线程变量中指定的数据源）
*/
@Intercepts({
@Signature(type = Executor.class, method = "update", args = {MappedStatement.class, Object.class}),
@Signature(type = Executor.class, method = "query", args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class}),
@Signature(type = Executor.class, method = "query", args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class, CacheKey.class, BoundSql.class})
})
@Component
public class MybatisDataSourceInterceptor implements Interceptor {
@Override
public Object intercept(Invocation invocation) throws Throwable {
boolean synchronizationActive = TransactionSynchronizationManager.isSynchronizationActive();
if (!synchronizationActive) {
Object[] objects = invocation.getArgs();
MappedStatement ms = (MappedStatement) objects[0];
if (ms.getSqlCommandType().equals(SqlCommandType.SELECT)) {
//不在事务中，且调用的sql是select类型时，选择从库。其他情况，默认选择主库
DataSourceHolder.putDataSource(DataSourceHolder.getRandomReadDataSourceName());
}
}
return invocation.proceed();
}
@Override
public Object plugin(Object target) {
return Plugin.wrap(target, this);
}
@Override
public void setProperties(Properties properties) {
}
}
3.4 启动类配置
@SpringBootApplication(scanBasePackages = "com.sa.example")
@MapperScan(basePackages = {"com.sa.example.mybatis2.ext.mapper", "com.sa.example.mybatis2.auto.mapper"})
public class Mybatis2Application {
public static void main(String[] args) {
SpringApplication.run(Mybatis2Application.class, args);
}
}
4 使用
4.1 建表脚本
CREATE TABLE `c_m_phone` (
`id` int(10) NOT NULL COMMENT 'id',
`phone_first` varchar(20) DEFAULT NULL COMMENT '前缀号段',
`phone_provence` varchar(20) DEFAULT NULL COMMENT '手机所在省份',
`phone_city` varchar(20) DEFAULT NULL COMMENT '手机所在城市',
`service` varchar(20) DEFAULT NULL COMMENT '服务商',
PRIMARY KEY (`id`)
) COMMENT='电话区域表';
4.2 实体类
//包名：com.sa.example.mybatis2.ext.bean
@Data
public class CMPhone {
private Integer id;
private String phoneFirst;
private String phoneProvence;
private String phoneCity;
private String service;
}
4.3 mapper
// 包名：com.sa.example.mybatis2.ext.mapper
public interface CMPhoneMapper {
/**
* 保存（配置主库）
* @param model
* @return
*/
int save(CMPhone model);
/**
* 查询（配置从库）
* @param model
* @return
*/
List findList(CMPhone model);
}
4.4 mapper映射
INSERT INTO `c_m_phone` (`id`, `phone_first`, `phone_provence`, `phone_city`, `service`) VALUES (
#{id},#{phoneFirst},#{phoneProvence},#{phoneCity},#{service}
)
4.5 使用
@RunWith(SpringRunner.class)
@SpringBootTest(classes = MybatisApplication.class)
public class MybatisTest {
@Autowired
private CMPhoneMapper cmPhoneMapper;
@Test
public void testMapper() {
List cmPhoneList = cmPhoneMapper.findList(new CMPhone());
System.out.println(cmPhoneList);
}
@Test
public void testSave(){
CMPhone model = new CMPhone();
model.setId(1000);
model.setPhoneCity("PhoneCity test");
model.setPhoneFirst("PhoneFirst test");
model.setPhoneProvence("PhoneProvence test");
model.setService("Service test");
cmPhoneMapper.save(model);
}
}
4.6 事务中的查询
事务中的查询，连接的为主库master
4.6.1 service
public interface CMPhoneService {
List doSomething();
}
@Service
public class CMPhoneServiceImpl implements CMPhoneService {
@Autowired
private CMPhoneMapper cmPhoneMapper;
@Transactional(rollbackFor = RuntimeException.class)
@Override
public List doSomething() {
return cmPhoneMapper.findList(new CMPhone());
}
}
4.6.2 单元测试
@Test
public void testTransaction(){
List cmPhoneList = cmPhoneService.doSomething();
System.out.println(cmPhoneList);
}
4.6.3 输出日志
Creating a new SqlSession
Registering transaction synchronization for SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@79c5460e]
JDBC Connection [com.alibaba.druid.proxy.jdbc.ConnectionProxyImpl@7ab4ae59] will be managed by Spring
==> Preparing: select id,phone_first,phone_provence,phone_city,service from c_m_phone
==> Parameters:
<== Columns: id, phone_first, phone_provence, phone_city, service
<== Row: 1, 1300000, 山东, 济南, 中国联通
<== Total: 1
Releasing transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@79c5460e]
Transaction synchronization committing SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@79c5460e]
Transaction synchronization deregistering SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@79c5460e]
Transaction synchronization closing SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@79c5460e]