大厂 SpringBoot + MyBatis + MySQL读写分离实践！
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1. 引言
2. AbstractRoutingDataSource
3. 实践
3.1. maven依赖
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0
</modelVersion>
<groupId>com.cjs.example
</groupId>
<artifactId>cjs-datasource-demo
</artifactId>
<version>0.0.1-SNAPSHOT
</version>
<packaging>jar
</packaging>
<name>cjs-datasource-demo
</name>
<description></description>
<parent>
<groupId>org.springframework.boot
</groupId>
<artifactId>spring-boot-starter-parent
</artifactId>
<version>2.0.5.RELEASE
</version>
<relativePath/>
<!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8
</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8
</project.reporting.outputEncoding>
<java.version>1.8
</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot
</groupId>
<artifactId>spring-boot-starter-aop
</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot
</groupId>
<artifactId>spring-boot-starter-jdbc
</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot
</groupId>
<artifactId>spring-boot-starter-web
</artifactId>
</dependency>
<dependency>
<groupId>org.mybatis.spring.boot
</groupId>
<artifactId>mybatis-spring-boot-starter
</artifactId>
<version>1.3.2
</version>
</dependency>
<dependency>
<groupId>org.apache.commons
</groupId>
<artifactId>commons-lang3
</artifactId>
<version>3.8
</version>
</dependency>
<dependency>
<groupId>mysql
</groupId>
<artifactId>mysql-connector-java
</artifactId>
<scope>runtime
</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot
</groupId>
<artifactId>spring-boot-starter-test
</artifactId>
<scope>test
</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot
</groupId>
<artifactId>spring-boot-maven-plugin
</artifactId>
</plugin>
<!--<plugin>
<groupId>org.mybatis.generator</groupId>
<artifactId>mybatis-generator-maven-plugin</artifactId>
<version>1.3.5</version>
<dependencies>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.46</version>
</dependency>
</dependencies>
<configuration>
<configurationFile>${basedir}/src/main/resources/myBatisGeneratorConfig.xml</configurationFile>
<overwrite>true</overwrite>
</configuration>
<executions>
<execution>
<id>Generate MyBatis Artifacts</id>
<goals>
<goal>generate</goal>
</goals>
</execution>
</executions>
</plugin>-->
</plugins>
</build>
</project>
3.2. 数据源配置
spring:
datasource:
master:
jdbc-url: jdbc:mysql:
//192.168.102.31:3306/test
username: root
password:
123456
driver-
class-name: com.mysql.jdbc.Driver
slave1:
jdbc-url: jdbc:mysql:
//192.168.102.56:3306/test
username: pig # 只读账户
password:
123456
driver-
class-name: com.mysql.jdbc.Driver
slave2:
jdbc-url: jdbc:mysql:
//192.168.102.36:3306/test
username: pig # 只读账户
password:
123456
driver-
class-name: com.mysql.jdbc.Driver
多数据源配置
package com.cjs.example.config;
import com.cjs.example.bean.MyRoutingDataSource;
import com.cjs.example.enums.DBTypeEnum;
import org.springframework.beans.factory.
annotation.Qualifier;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.jdbc.DataSourceBuilder;
import org.springframework.context.
annotation.Bean;
import org.springframework.context.
annotation.Configuration;
import javax.sql.DataSource;
import java.util.HashMap;
import java.util.Map;
/**
* 关于数据源配置，参考SpringBoot官方文档第79章《Data Access》
* 79. Data Access
* 79.1 Configure a Custom DataSource
* 79.2 Configure Two DataSources
*/
@Configuration
public
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
@ConfigurationProperties("spring.datasource.slave2")
public DataSource slave2DataSource() {
return DataSourceBuilder.create().build();
}
@Bean
public DataSource myRoutingDataSource(
@Qualifier("masterDataSource") DataSource masterDataSource,
@Qualifier("slave1DataSource") DataSource slave1DataSource,
@Qualifier("slave2DataSource") DataSource slave2DataSource) {
Map<Object, Object> targetDataSources = new HashMap<>();
targetDataSources.put(DBTypeEnum.MASTER, masterDataSource);
targetDataSources.put(DBTypeEnum.SLAVE1, slave1DataSource);
targetDataSources.put(DBTypeEnum.SLAVE2, slave2DataSource);
MyRoutingDataSource myRoutingDataSource = new MyRoutingDataSource();
myRoutingDataSource.setDefaultTargetDataSource(masterDataSource);
myRoutingDataSource.setTargetDataSources(targetDataSources);
return myRoutingDataSource;
}
}
MyBatis配置
package com.cjs.example.config;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.springframework.context.
annotation.Bean;
import org.springframework.context.
annotation.Configuration;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.
annotation.EnableTransactionManagement;
import javax.
annotation.Resource;
import javax.sql.DataSource;
@EnableTransactionManagement
@Configuration
public
class MyBatisConfig {
@Resource(name = "myRoutingDataSource")
private DataSource myRoutingDataSource;
@Bean
public SqlSessionFactory sqlSessionFactory() throws Exception {
SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();
sqlSessionFactoryBean.setDataSource(myRoutingDataSource);
sqlSessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver().getResources(
"classpath:mapper/*.xml"));
return sqlSessionFactoryBean.getObject();
}
@Bean
public PlatformTransactionManager platformTransactionManager() {
return new DataSourceTransactionManager(myRoutingDataSource);
}
}
3.3 设置路由key / 查找数据源
package com.cjs.example.enums;
public
enum DBTypeEnum {
MASTER, SLAVE1, SLAVE2;
}
package com.cjs.example.bean;
import com.cjs.example.enums.DBTypeEnum;
import java.util.concurrent.atomic.AtomicInteger;
public
class
DBContextHolder {
private
static final ThreadLocal<DBTypeEnum> contextHolder =
new ThreadLocal<>();
private
static final AtomicInteger counter =
new AtomicInteger(
-1);
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(
"切换到master");
}
public static void slave() {
// 轮询
int index = counter.getAndIncrement() %
2;
if (counter.
get() >
9999) {
counter.
set(
-1);
}
if (index ==
0) {
set(DBTypeEnum.SLAVE1);
System.
out.println(
"切换到slave1");
}
else {
set(DBTypeEnum.SLAVE2);
System.
out.println(
"切换到slave2");
}
}
}
获取路由key
package com.cjs.example.bean;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
import org.springframework.lang.Nullable;
public
class MyRoutingDataSource extends AbstractRoutingDataSource {
@Nullable
@Override
protected Object determineCurrentLookupKey() {
return DBContextHolder.get();
}
}
设置路由key
package com.cjs.example.aop;
import com.cjs.example.bean.DBContextHolder;
import org.apache.commons.lang3.StringUtils;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
import org.springframework.stereotype.Component;
@Aspect
@Component
public
class DataSourceAop {
@Pointcut(
"!@annotation(com.cjs.example.annotation.Master) " +
"&& (execution(* com.cjs.example.service..*.select*(..)) " +
"|| execution(* com.cjs.example.service..*.get*(..)))")
public void readPointcut() {
}
@Pointcut(
"@annotation(com.cjs.example.annotation.Master) " +
"|| execution(* com.cjs.example.service..*.insert*(..)) " +
"|| execution(* com.cjs.example.service..*.add*(..)) " +
"|| execution(* com.cjs.example.service..*.update*(..)) " +
"|| execution(* com.cjs.example.service..*.edit*(..)) " +
"|| execution(* com.cjs.example.service..*.delete*(..)) " +
"|| execution(* com.cjs.example.service..*.remove*(..))")
public void writePointcut() {
}
@Before(
"readPointcut()")
public void read() {
DBContextHolder.slave();
}
@Before(
"writePointcut()")
public void write() {
DBContextHolder.master();
}
/**
* 另一种写法：if...else... 判断哪些需要读从数据库，其余的走主数据库
*/
// @Before("execution(* com.cjs.example.service.impl.*.*(..))")
// public void before(JoinPoint jp) {
// String methodName = jp.getSignature().getName();
//
// if (StringUtils.startsWithAny(methodName, "get", "select", "find")) {
// DBContextHolder.slave();
// }else {
// DBContextHolder.master();
// }
// }
}
package
com
.cjs.example.annotation;
public @
interface Master {
}
package com.cjs.example.service.impl;
import com.cjs.example.annotation.Master;
import com.cjs.example.entity.Member;
import com.cjs.example.entity.MemberExample;
import com.cjs.example.mapper.MemberMapper;
import com.cjs.example.service.MemberService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import java.util.List;
@Service
public
class MemberServiceImpl implements MemberService {
@Autowired
private MemberMapper memberMapper;
@Transactional
@Override
public int insert(Member member) {
return memberMapper.insert(member);
}
@Master
@Override
public int save(Member member) {
return memberMapper.insert(member);
}
@Override
public List<Member> selectAll() {
return memberMapper.selectByExample(
new MemberExample());
}
@Master
@Override
public String getToken(String appId) {
// 有些读操作必须读主数据库
// 比如，获取微信access_token，因为高峰时期主从同步可能延迟
// 这种情况下就必须强制从主数据读
return
null;
}
}
4. 测试
package com.cjs.example;
import com.cjs.example.entity.Member;
import com.cjs.example.service.MemberService;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
@RunWith(SpringRunner.class)
@SpringBootTest
public
class CjsDatasourceDemoApplicationTests {
@Autowired
private MemberService memberService;
@Test
public void testWrite() {
Member member =
new Member();
member.setName(
"zhangsan");
memberService.insert(member);
}
@Test
public void testRead() {
for (
int i =
0; i <
4; i++) {
memberService.selectAll();
}
}
@Test
public void testSave() {
Member member =
new Member();
member.setName(
"wangwu");
memberService.save(member);
}
@Test
public void testReadFromMaster() {
memberService.getToken(
"1234");
}
}
5. 工程结构
6. 参考
https:
//www.jianshu.com/p/f2f4256a2310
http:
//www.cnblogs.com/gl-developer/p/6170423.html
https:
//www.cnblogs.com/huangjuncong/p/8576935.html
https:
//blog.csdn.net/liu976180578/article/details/77684583
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