序言：这个读写分离摘自于Springboot多数据源快速启动器，读写分离的话并不是按照传统方式的springmvc看方法命名那样，而是在每个方法上加注解或者类上添加注解表明选用的数据源。支持事物！

1、创建Springboot项目

勾选Web，Mysql，MyBatis三个模块，最终创建springboot项目成功

2、pom.xml 添加属性依赖

<!-- springboot-aop包,AOP切面注解,Aspectd等相关注解 -->
<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-aop</artifactId>
</dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-configuration-processor</artifactId><optional>true</optional>
</dependency>
<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>

3、添加application.properties 属性配置

server.port=8088
#数据源1
spring.datasource.db1.jdbc-url=jdbc:mysql://127.0.0.1:3306/test_msg2?useUnicode=true&characterEncoding=utf-8&useSSL=false
spring.datasource.db1.username=root
spring.datasource.db1.password=root
spring.datasource.db1.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.db1.max-idle=10
spring.datasource.db1.max-wait=10000
spring.datasource.db1.min-idle=5
spring.datasource.db1.initial-size=5
#数据源2
spring.datasource.db2.jdbc-url=jdbc:mysql://127.0.0.1:3306/test_msg3?useUnicode=true&characterEncoding=utf-8&useSSL=false
spring.datasource.db2.username=root
spring.datasource.db2.password=root
spring.datasource.db2.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.db2.max-idle=10
spring.datasource.db2.max-wait=10000
spring.datasource.db2.min-idle=5
spring.datasource.db2.initial-size=5
#mybatis
mybatis.mapper-locations=classpath*:mapper/*.xml
mybatis.type-aliases-package=com.springboot2.mjt04.dao

4、编写代码

4.0 实体类

public class User {private int id;private String name;private int age;public User(){}public User(String name, int age){this.name = name;this.age  = age;}public int getId() {return id;}public void setId(int id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}
}

4.1 创建UserDao.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" ><mapper namespace="com.springboot2.mjt04.dao.UserDao"><!-- 查询所有user --><select id="getAllUser" resultType="java.util.Map">select * from user</select><!-- 添加数据并返回主键ID,接收主键,必须以实体类接收 --><!-- keyColumn="id"对应数据库字段,keyProperty="id"对应实体类属性  --><insert id="addUserGetID" parameterType="com.springboot2.mjt04.entity.User" useGeneratedKeys="true" keyColumn="id" keyProperty="id">insert into user(name,age) values(#{name},#{age})</insert><insert id="addUser">insert into user(name,age) values(#{name},#{age})</insert>
</mapper>

4.2 UserDao

@Mapper
public interface UserDao {//使用xml配置形式查询List<Map> getAllUser();Long addUserGetID(User user);void addUser(User user);
}

4.3 UserService

@Service
public class UserService {@Autowiredprivate UserDao moredataDao;//使用数据源1查询@DS("datasource1")public List<Map> getAllUser1(){return moredataDao.getAllUser();}//使用数据源2查询@DS("datasource2")public List<Map> getAllUser2(){return moredataDao.getAllUser();}//使用数据源1插入数据@DS("datasource1")public Long addUserGetID1(User user){return moredataDao.addUserGetID(user);}//使用数据源1插入数据@DS("datasource2")public Long addUserGetID2(User user){return moredataDao.addUserGetID(user);}//使用数据源1插入数据@DS("datasource1")public void addUser1(User user){moredataDao.addUser(user);}//使用数据源2插入数据@DS("datasource2")public void addUser2(User user){moredataDao.addUser(user);}@Transactionalpublic void test1(){moredataDao.addUserGetID(new User("mdx1",18));int a =10/0;moredataDao.addUserGetID(new User("mdxl1",20));}}

4.4 创建controller

@Controller
public class RWController {@AutowiredUserService userService;//走数据源1库@GetMapping(value = "/test1")@ResponseBodypublic String testOne(){User user = new User("mjt01",20);userService.addUser1(user);return "success";}//使用数据源2插入数据@GetMapping(value = "/test2")@ResponseBodypublic String testTwo(){User user = new User("mjt02",20);userService.addUser2(user);return "success";}}

4.5 添加mysql多数据源配置文件类

5个配置文件，切记如果照着写的话，小心里面的路径要准确对应上

//import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
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 org.springframework.context.annotation.Primary;
import org.springframework.jdbc.datasource.DataSourceTransactionManager;
import org.springframework.transaction.PlatformTransactionManager;import javax.sql.DataSource;
import java.util.HashMap;
import java.util.Map;/*** 多数据源配置类* Created by pure on 2018-05-06.*/
@Configuration
public class DataSourceConfig {//数据源1@Bean(name = "datasource1")@ConfigurationProperties(prefix = "spring.datasource.db1") // application.properteis中对应属性的前缀public DataSource dataSource1() {return DataSourceBuilder.create().build();}//数据源2@Bean(name = "datasource2")@ConfigurationProperties(prefix = "spring.datasource.db2") // application.properteis中对应属性的前缀public DataSource dataSource2() {return DataSourceBuilder.create().build();}/*** 动态数据源: 通过AOP在不同数据源之间动态切换* @return*/@Primary@Bean(name = "dynamicDataSource")public DataSource dynamicDataSource() {DynamicDataSource dynamicDataSource = new DynamicDataSource();// 默认数据源dynamicDataSource.setDefaultTargetDataSource(dataSource1());// 配置多数据源Map<Object, Object> dsMap = new HashMap();dsMap.put("datasource1", dataSource1());dsMap.put("datasource2", dataSource2());dynamicDataSource.setTargetDataSources(dsMap);return dynamicDataSource;}/*** 配置@Transactional注解事物* @return*/@Beanpublic PlatformTransactionManager transactionManager() {return new DataSourceTransactionManager(dynamicDataSource());}
}

public class DataSourceContextHolder {/*** 默认数据源*/public static final String DEFAULT_DS = "datasource1";private static final ThreadLocal<String> contextHolder = new ThreadLocal<>();// 设置数据源名public static void setDB(String dbType) {System.out.println("切换到{"+dbType+"}数据源");contextHolder.set(dbType);}// 获取数据源名public static String getDB() {return (contextHolder.get());}// 清除数据源名public static void clearDB() {contextHolder.remove();}
}

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD})
public @interface DS {String value() default "datasource1";
}

public class DynamicDataSource extends AbstractRoutingDataSource {@Overrideprotected Object determineCurrentLookupKey() {System.out.println("数据源为"+DataSourceContextHolder.getDB());return DataSourceContextHolder.getDB();}
}

@Aspect
@Component
public class DynamicDataSourceAspect {@Before("@annotation(com.springboot2.mjt04.config.mysql.DS)")public void beforeSwitchDS(JoinPoint point){//获得当前访问的classClass<?> className = point.getTarget().getClass();//获得访问的方法名String methodName = point.getSignature().getName();//得到方法的参数的类型Class[] argClass = ((MethodSignature)point.getSignature()).getParameterTypes();String dataSource = DataSourceContextHolder.DEFAULT_DS;try {// 得到访问的方法对象Method method = className.getMethod(methodName, argClass);// 判断是否存在@DS注解if (method.isAnnotationPresent(DS.class)) {DS annotation = method.getAnnotation(DS.class);// 取出注解中的数据源名dataSource = annotation.value();}} catch (Exception e) {e.printStackTrace();}// 切换数据源DataSourceContextHolder.setDB(dataSource);}@After("@annotation(com.springboot2.mjt04.config.mysql.DS)")public void afterSwitchDS(JoinPoint point){DataSourceContextHolder.clearDB();}
}

最终目录结构图：

5、注意的问题：

5.1 出现这个错误 jdbcUrl is required with driverClassName.运行出现这个过程是因为在多数据源的情况下，springboot2.0与1.X版本都不同配置属性，解决jdbcUrl is required with driverClassName.问题，点击这里，但是我现在已经改过来了，以前是

spring.datasource.db1.url=jdbc:mysql://127.0.0.1:3306/test_msg2?useUnicode=true&characterEncoding=utf-8&useSSL=false

而现在添加了jdbc-url

spring.datasource.db1.jdbc-url=jdbc:mysql://127.0.0.1:3306/test_msg2?useUnicode=true&characterEncoding=utf-8&useSSL=false

5.2 包名路径跟换

以前1.X版本为

import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;

而现在2.X版本

import org.springframework.boot.jdbc.DataSourceBuilder;

注意一下就好，因为我都给大家改好了。

5.3 事物可以正常使用，也支持读写分离，不过在事物的方法可能比springmvc的项目麻烦些，毕竟目前我的技术只能用注解才能切换数据源，目前我没有成功找到在配置类根据方法前缀名就可以判断数据源的。

5.4

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})

这个是application启动类上面的一个注解，表明是不使用DataSourceAutoCOnfiguration.class,因为我们的是多个数据源，不能默认使用一个单数据源，所以要加上这个。

成功！不懂可以私信我或者留言就好。