spring整合mybatis的核心思路（数据源切换）

文章目录

- 1. 整合思路
- 2. 最简单的整合步骤
- - 1. 导入依赖
  - 2. 准备基础类
  - - User
    - UserMapper
    - userMapper.xml
    - MybatisConfig
  - 3. 测试
  - - TestMybatisSpring
- 3. 整合多个mybatis配置
- - 1. 修改MybatisConfig
  - 2. 测试
  - - TestMybatisSpring
- 4. AbstractRoutingDataSource实现源切换
- - 1. 准备基础类
  - - Person
    - PersonMapper
    - CustomizeRoutingDataSource
  - 2. 修改MyBatisConfig
  - 3. 测试
  - - TestMybatisSpring
- 5. mybatis插件实现切换数据源
- - 1. DsPlugin
  - 2. 修改MybatisConfig
  - 3.测试
  - - TestMybatisSpring

1. 整合思路

@MapperScan注解 -> 引入了MapperScannerRegistrar注册器 -> 该注册器向容器中MapperScannerConfigurer这个configurer是个BeanDefinitionRegistryPostProcessor，它在重写的postProcessBeanDefinitionRegistry方法中使用了ClassPathMapperScanner来扫描指定的包中的mapper接口 -> ClassPathMapperScanner(如果未指定sqlSessionTemplateBeanName，也没有指定sqlSessionFactoryBeanName，将会设置按类型自动注入SqlSessionFactory和SqlSessionTemplate(实现了SqlSession接口，委托给SqlSessionInterceptor，即每次调用SqlSession中的任何方法都会走SqlSessionInterceptor#invoke方法，这是为了控制事务)，仅须其中一个即可) -> 扫包中的每一个beanDefinition都会设置beanClass为MapperFactoryBean，而MapperFactoryBean#getObject方法就会获取sqlSessionTemplate（它实现了SqlSession接口），并调用sqlSessionTemplate.getMapper(接口类)方法，来获取动态代理 -> 而每次使用动态代理的方法都会调用sqlSessionTemplate -> 而sqlSessionTemplate则也会委托给SqlSessionInterceptor-> 此时去从SqlSessionFactory获取sqlSession

2. 最简单的整合步骤

在这里插入图片描述

1. 导入依赖

<?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.zzhua</groupId>
    <artifactId>mybatis-spring-demo</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.0.2.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.0.2.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.2</version>
        </dependency>

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.7</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.17</version>
        </dependency>



        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.16</version>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.6.0</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>

        </plugins>
    </build>


</project>

2. 准备基础类

User

@Data
public class User {

    private String userAccount;

}

UserMapper

public interface UserMapper {

    List<User> findAll();

    @Select("select * from `user` u where u.user_account = #{userAccount}")
    User findOne(String userAccount);

}

userMapper.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.zzhua.mapper.UserMapper">

   <select id="findAll" resultType="user">
       select * from `user`
   </select>


</mapper>

MybatisConfig

package com.zzhua.config;

import org.apache.ibatis.session.ExecutorType;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.SqlSessionTemplate;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.jdbc.datasource.DriverManagerDataSource;

import java.io.IOException;

@Configuration
@MapperScan(basePackages = "com.zzhua.mapper")
public class MybatisConfig {

    @Bean // 如果不配置该bean，将会抛出Caused by: java.lang.IllegalArgumentException: Property 'sqlSessionFactory' or 'sqlSessionTemplate' are required异常
    public SqlSessionFactoryBean sqlSessionFactoryBean() throws IOException { // 代码写法可参考SqlSessionFactoryBean#afterPropertiesSet

        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();

        // 设置数据源
        DriverManagerDataSource driverManagerDataSource = new DriverManagerDataSource();
        driverManagerDataSource.setUrl("jdbc:mysql://127.0.0.1/user?serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&useSSL=false&allowPublicKeyRetrieval=true");
        driverManagerDataSource.setDriverClassName("com.mysql.cj.jdbc.Driver");
        driverManagerDataSource.setUsername("root");
        driverManagerDataSource.setPassword("root");
        sqlSessionFactoryBean.setDataSource(driverManagerDataSource);

        // 自定义Configuration
        org.apache.ibatis.session.Configuration configuration = new org.apache.ibatis.session.Configuration();
        configuration.setMapUnderscoreToCamelCase(true);
        configuration.getTypeAliasRegistry().registerAliases("com.zzhua.pojo");
        sqlSessionFactoryBean.setConfiguration(configuration);

        // 指定mapper.xml文件
        PathMatchingResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();
        sqlSessionFactoryBean.setMapperLocations(resourcePatternResolver.getResources("classpath:com/zzhua/mapper/**.xml"));

        return sqlSessionFactoryBean; // # 之后会调用SqlSessionFactoryBean#afterPropertiesSet()方法
    }

    @Bean
    public SqlSessionTemplate sqlSessionTemplate(SqlSessionFactory sqlSessionFactory) {
        return new SqlSessionTemplate(sqlSessionFactory, ExecutorType.BATCH);
    }

}

3. 测试

TestMybatisSpring

public class TestMybatisSpring {
    public static void main(String[] args) {

        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(MybatisConfig.class);

        UserMapper userMapper = context.getBean(UserMapper.class);

        List<User> userList = userMapper.findAll();
        System.out.println(userList);

        User user = userMapper.findOne("zzhua");
        System.out.println(user);


    }
}

3. 整合多个mybatis配置

创建2个数据库，一个user库（里面有一张user表）和user2库（里面有一张user2表）。现在需要使用mybatis来操作这2个库中的表。
在这里插入图片描述

1. 修改MybatisConfig

@Configuration
@MapperScan(basePackages = "com.zzhua.dao.mapper", sqlSessionFactoryRef = "sqlSessionFactoryBean")
public class MybatisConfig {

    @Bean // 如果不配置该bean，将会抛出Caused by: java.lang.IllegalArgumentException: Property 'sqlSessionFactory' or 'sqlSessionTemplate' are required异常
    public SqlSessionFactoryBean sqlSessionFactoryBean() throws IOException { // 代码写法可参考SqlSessionFactoryBean#afterPropertiesSet

        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();

        // 设置数据源
        DriverManagerDataSource driverManagerDataSource = new DriverManagerDataSource();
        driverManagerDataSource.setUrl("jdbc:mysql://127.0.0.1/user?serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&useSSL=false&allowPublicKeyRetrieval=true");
        driverManagerDataSource.setDriverClassName("com.mysql.cj.jdbc.Driver");
        driverManagerDataSource.setUsername("root");
        driverManagerDataSource.setPassword("root");
        sqlSessionFactoryBean.setDataSource(driverManagerDataSource);

        // 自定义Configuration
        org.apache.ibatis.session.Configuration configuration = new org.apache.ibatis.session.Configuration();
        configuration.setMapUnderscoreToCamelCase(true);
        configuration.getTypeAliasRegistry().registerAliases("com.zzhua.pojo");
        sqlSessionFactoryBean.setConfiguration(configuration);

        // 指定mapper.xml文件
        PathMatchingResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();
        sqlSessionFactoryBean.setMapperLocations(resourcePatternResolver.getResources("classpath:com/zzhua/mapper/**.xml"));

        return sqlSessionFactoryBean; // # 之后会调用SqlSessionFactoryBean#afterPropertiesSet()方法
    }

    @Configuration
    @MapperScan(basePackages = "com.zzhua.dao.mapper2", sqlSessionFactoryRef = "sqlSessionFactoryBean2")
    public static class MybatisConfig2 {

        @Bean
        // 如果不配置该bean，将会抛出Caused by: java.lang.IllegalArgumentException: Property 'sqlSessionFactory' or 'sqlSessionTemplate' are required异常
        public SqlSessionFactoryBean sqlSessionFactoryBean2() throws IOException { // 代码写法可参考SqlSessionFactoryBean#afterPropertiesSet

            SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();

            // 设置数据源
            DriverManagerDataSource driverManagerDataSource = new DriverManagerDataSource();
            driverManagerDataSource.setUrl("jdbc:mysql://127.0.0.1/user2?serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&useSSL=false&allowPublicKeyRetrieval=true");
            driverManagerDataSource.setDriverClassName("com.mysql.cj.jdbc.Driver");
            driverManagerDataSource.setUsername("root");
            driverManagerDataSource.setPassword("root");
            sqlSessionFactoryBean.setDataSource(driverManagerDataSource);

            // 自定义Configuration
            org.apache.ibatis.session.Configuration configuration = new org.apache.ibatis.session.Configuration();
            configuration.setMapUnderscoreToCamelCase(true);
            configuration.getTypeAliasRegistry().registerAliases("com.zzhua.pojo");
            sqlSessionFactoryBean.setConfiguration(configuration);

            // 指定mapper.xml文件
            PathMatchingResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();
            sqlSessionFactoryBean.setMapperLocations(resourcePatternResolver.getResources("classpath:com/zzhua/mapper2/**.xml"));

            return sqlSessionFactoryBean; // # 之后会调用SqlSessionFactoryBean#afterPropertiesSet()方法
        }
    }

}

2. 测试

TestMybatisSpring

public class TestMybatisSpring {
    public static void main(String[] args) {

        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(MybatisConfig.class);

        UserMapper userMapper = context.getBean(UserMapper.class);

        List<User> userList = userMapper.findAll();
        System.out.println(userList);

        User user = userMapper.findOne("zzhua");
        System.out.println(user);

        System.out.println("--------------");

        UserMapper2 userMapper2 = context.getBean(UserMapper2.class);
        List<User2> userList2 = userMapper2.findAll2();
        System.out.println(userList2);

        User2 user2 = userMapper2.findOne2("zzhua2");
        System.out.println(user2);

    }
}

4. AbstractRoutingDataSource实现源切换

在user库中新建一张person表

1. 准备基础类

Person

@Data
public class Person {

    private String name;

}

PersonMapper

public interface PersonMapper {

    @Insert("insert into person values(#{name} )")
    void addPerson(String name);

    @Select("select * from person")
    List<Person> getPersons();

}

CustomizeRoutingDataSource

public class CustomizeRoutingDataSource extends AbstractRoutingDataSource {

    private static final ThreadLocal<String> DS_KEY = new ThreadLocal<>();

    @Override
    protected Object determineCurrentLookupKey() {
        return DS_KEY.get();
    }

    public static void setDsKey(String dsKey) {
        DS_KEY.set(dsKey);
    }

    public static void clearDsKey() {
        DS_KEY.remove();
    }

}

2. 修改MyBatisConfig

@Configuration
@MapperScan(basePackages = "com.zzhua.dao.mapper", sqlSessionFactoryRef = "sqlSessionFactoryBean")
public class MybatisConfig {

    @Bean
    public DataSource userDataSource() {
        DriverManagerDataSource driverManagerDataSource = new DriverManagerDataSource();
        driverManagerDataSource.setUrl("jdbc:mysql://127.0.0.1/user?serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&useSSL=false&allowPublicKeyRetrieval=true");
        driverManagerDataSource.setDriverClassName("com.mysql.cj.jdbc.Driver");
        driverManagerDataSource.setUsername("root");
        driverManagerDataSource.setPassword("root");
        return driverManagerDataSource;
    }

    @Bean
    public DataSource user2DataSource() {
        DriverManagerDataSource driverManagerDataSource = new DriverManagerDataSource();
        driverManagerDataSource.setUrl("jdbc:mysql://127.0.0.1/user2?serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&useSSL=false&allowPublicKeyRetrieval=true");
        driverManagerDataSource.setDriverClassName("com.mysql.cj.jdbc.Driver");
        driverManagerDataSource.setUsername("root");
        driverManagerDataSource.setPassword("root");
        return driverManagerDataSource;
    }

    @Primary
    @Bean
    public DataSource primaryDataSource() {
    
        CustomizeRoutingDataSource routingDataSource = new CustomizeRoutingDataSource();

        // 指定默认数据源
        routingDataSource.setDefaultTargetDataSource(userDataSource());

        // 指定 标识->数据源 的map
        HashMap<Object, Object> dsMap = new HashMap<>();
        dsMap.put("user", userDataSource());
        dsMap.put("user2", user2DataSource());
        routingDataSource.setTargetDataSources(dsMap);


        return routingDataSource;
    }

    @Bean // 如果不配置该bean，将会抛出Caused by: java.lang.IllegalArgumentException: Property 'sqlSessionFactory' or 'sqlSessionTemplate' are required异常
    public SqlSessionFactoryBean sqlSessionFactoryBean(DataSource primaryDataSource) throws IOException { // 代码写法可参考SqlSessionFactoryBean#afterPropertiesSet

        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();

        // 设置数据源
        sqlSessionFactoryBean.setDataSource(primaryDataSource);

        // 自定义Configuration
        org.apache.ibatis.session.Configuration configuration = new org.apache.ibatis.session.Configuration();
        configuration.setMapUnderscoreToCamelCase(true);
        configuration.getTypeAliasRegistry().registerAliases("com.zzhua.pojo");
        sqlSessionFactoryBean.setConfiguration(configuration);

        // 指定mapper.xml文件
        PathMatchingResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();
        sqlSessionFactoryBean.setMapperLocations(resourcePatternResolver.getResources("classpath:com/zzhua/mapper/**.xml"));

        return sqlSessionFactoryBean; // # 之后会调用SqlSessionFactoryBean#afterPropertiesSet()方法
    }

}

3. 测试

TestMybatisSpring

public class TestMybatisSpring {

    public static void main(String[] args) {

        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(MybatisConfig.class);

        PersonMapper personMapper = context.getBean(PersonMapper.class);

        // 可使用注解 + AOP的方式简化代码, 在执行数据库操作之前设置所要操作的数据源标识

        CustomizeRoutingDataSource.setDsKey("user");
        personMapper.addPerson("zzhua");
        personMapper.addPerson("zj");
        List<Person> persons = personMapper.getPersons();
        System.out.println(persons);
        CustomizeRoutingDataSource.clearDsKey();


        CustomizeRoutingDataSource.setDsKey("user2");
        personMapper.addPerson("zzhua2");
        personMapper.addPerson("zj2");
        List<Person> persons2 = personMapper.getPersons();
        System.out.println(persons2);
        CustomizeRoutingDataSource.clearDsKey();

    }
}

5. mybatis插件实现切换数据源

在这里插入图片描述

1. DsPlugin

// Interceptor可拦截mybatis的四大对象中的方法
//      四大对象包括: Executor、StatementHandler、ParameterHandler、ResultSetHandler
@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}
    )
})
public class DsPlugin implements Interceptor {
    @Override
    public Object intercept(Invocation invocation) throws Throwable {

        Object[] args = invocation.getArgs();

        MappedStatement ms = ((MappedStatement) args[0]);

        if (SqlCommandType.SELECT.equals(ms.getSqlCommandType())) {
            CustomizeRoutingDataSource.setDsKey("user");
        } else {
            CustomizeRoutingDataSource.setDsKey("user2");
        }

        Object result = invocation.proceed();
        CustomizeRoutingDataSource.clearDsKey();
        return result;
    }
}

2. 修改MybatisConfig

@Configuration
@MapperScan(basePackages = "com.zzhua.dao.mapper", sqlSessionFactoryRef = "sqlSessionFactoryBean")
public class MybatisConfig {

    @Bean
    public DataSource userDataSource() {
        DriverManagerDataSource driverManagerDataSource = new DriverManagerDataSource();
        driverManagerDataSource.setUrl("jdbc:mysql://127.0.0.1/user?serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&useSSL=false&allowPublicKeyRetrieval=true");
        driverManagerDataSource.setDriverClassName("com.mysql.cj.jdbc.Driver");
        driverManagerDataSource.setUsername("root");
        driverManagerDataSource.setPassword("root");
        return driverManagerDataSource;
    }

    @Bean
    public DataSource user2DataSource() {
        DriverManagerDataSource driverManagerDataSource = new DriverManagerDataSource();
        driverManagerDataSource.setUrl("jdbc:mysql://127.0.0.1/user2?serverTimezone=Asia/Shanghai&useUnicode=true&characterEncoding=utf-8&zeroDateTimeBehavior=convertToNull&useSSL=false&allowPublicKeyRetrieval=true");
        driverManagerDataSource.setDriverClassName("com.mysql.cj.jdbc.Driver");
        driverManagerDataSource.setUsername("root");
        driverManagerDataSource.setPassword("root");
        return driverManagerDataSource;
    }

    @Primary
    @Bean
    public DataSource primaryDataSource() {
        CustomizeRoutingDataSource routingDataSource = new CustomizeRoutingDataSource();

        // 指定默认数据源
        routingDataSource.setDefaultTargetDataSource(userDataSource());

        // 指定 标识->数据源 的map
        HashMap<Object, Object> dsMap = new HashMap<>();
        dsMap.put("user", userDataSource());
        dsMap.put("user2", user2DataSource());
        routingDataSource.setTargetDataSources(dsMap);


        return routingDataSource;
    }

    @Bean // 如果不配置该bean，将会抛出Caused by: java.lang.IllegalArgumentException: Property 'sqlSessionFactory' or 'sqlSessionTemplate' are required异常
    public SqlSessionFactoryBean sqlSessionFactoryBean(DataSource primaryDataSource) throws IOException { // 代码写法可参考SqlSessionFactoryBean#afterPropertiesSet

        SqlSessionFactoryBean sqlSessionFactoryBean = new SqlSessionFactoryBean();

        // 设置数据源
        sqlSessionFactoryBean.setDataSource(primaryDataSource);

        // 自定义Configuration
        org.apache.ibatis.session.Configuration configuration = new org.apache.ibatis.session.Configuration();
        configuration.setMapUnderscoreToCamelCase(true);
        configuration.getTypeAliasRegistry().registerAliases("com.zzhua.pojo");

        // 添加插件
        configuration.addInterceptor(new DsPlugin());

        sqlSessionFactoryBean.setConfiguration(configuration);

        // 指定mapper.xml文件
        PathMatchingResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();
        sqlSessionFactoryBean.setMapperLocations(resourcePatternResolver.getResources("classpath:com/zzhua/mapper/**.xml"));

        return sqlSessionFactoryBean; // # 之后会调用SqlSessionFactoryBean#afterPropertiesSet()方法
    }

}

3.测试

TestMybatisSpring

public class TestMybatisSpring {
    public static void main(String[] args) {

        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(MybatisConfig.class);

        PersonMapper personMapper = context.getBean(PersonMapper.class);

        personMapper.addPerson("zzhua11");
        personMapper.addPerson("zj11");

        List<Person> persons = personMapper.getPersons();
        System.out.println(persons);
    }
}