本文源码：GitHub·点这里 || GitEE·点这里

一、项目案例简介

1、多数据简介

实际的项目中，经常会用到不同的数据库以满足项目的实际需求。随着业务的并发量的不断增加，一个项目使用多个数据库：主从复制、读写分离、分布式数据库等方式，越来越常见。

2、MybatisPlus简介

MyBatis-Plus（简称 MP）是一个MyBatis的增强工具，在MyBatis的基础上只做增强不做改变，为简化开发、提高效率而生。

插件特点

无代码侵入：只做增强不做改变，引入它不会对现有工程产生影响。
强大的 CRUD 操作：通过少量配置即可实现单表大部分 CRUD 操作满足各类使用需求。
支持 Lambda 形式调用：通过 Lambda 表达式，方便的编写各类查询条件。
支持主键自动生成：可自由配置，解决主键问题。
内置代码生成器：采用代码或者 Maven 插件可快速生成各层代码。
内置分页插件：基于 MyBatis 物理分页，开发者无需关心具体操作。
内置性能分析插件：可输出 Sql 语句以及其执行时间。

二、多数据源案例

1、项目结构

注意：mapper层和mapper.xml层分别放在不同目录下，以便mybatis扫描加载。

2、多数据源配置

spring:
  # 数据源配置
  datasource:
    type: com.alibaba.druid.pool.DruidDataSource
    admin-data:
      driverClassName: com.mysql.jdbc.Driver
      dbUrl: jdbc:mysql://127.0.0.1:3306/cloud-admin-data?useUnicode=true&characterEncoding=UTF8&zeroDateTimeBehavior=convertToNull&useSSL=false
      username: root
      password: 123
      initialSize: 20
      maxActive: 100
      minIdle: 20
      maxWait: 60000
      poolPreparedStatements: true
      maxPoolPreparedStatementPerConnectionSize: 30
      timeBetweenEvictionRunsMillis: 60000
      minEvictableIdleTimeMillis: 30000
      maxEvictableIdleTimeMillis: 60000
      validationQuery: SELECT 1 FROM DUAL
      testOnBorrow: false
      testOnReturn: false
      testWhileIdle: true
      connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000
      filters: stat,wall
    user-data:
      driverClassName: com.mysql.jdbc.Driver
      dbUrl: jdbc:mysql://127.0.0.1:3306/cloud-user-data?useUnicode=true&characterEncoding=UTF8&zeroDateTimeBehavior=convertToNull&useSSL=false
      username: root
      password: 123
      initialSize: 20
      maxActive: 100
      minIdle: 20
      maxWait: 60000
      poolPreparedStatements: true
      maxPoolPreparedStatementPerConnectionSize: 30
      timeBetweenEvictionRunsMillis: 60000
      minEvictableIdleTimeMillis: 30000
      maxEvictableIdleTimeMillis: 60000
      validationQuery: SELECT 1 FROM DUAL
      testOnBorrow: false
      testOnReturn: false
      testWhileIdle: true
      connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000
      filters: stat,wall

这里参数的形式是多样的，只需要配置参数扫描即可。

3、参数扫描类

@Component
@ConfigurationProperties(prefix = "spring.datasource.admin-data")
public class DruidOneParam {
    private String dbUrl;
    private String username;
    private String password;
    private String driverClassName;
    private int initialSize;
    private int maxActive;
    private int minIdle;
    private int maxWait;
    private boolean poolPreparedStatements;
    private int maxPoolPreparedStatementPerConnectionSize;
    private int timeBetweenEvictionRunsMillis;
    private int minEvictableIdleTimeMillis;
    private int maxEvictableIdleTimeMillis;
    private String validationQuery;
    private boolean testWhileIdle;
    private boolean testOnBorrow;
    private boolean testOnReturn;
    private String filters;
    private String connectionProperties;
    // 省略 GET 和 SET
}

4、配置Druid连接池

@Configuration
@MapperScan(basePackages = {"com.data.source.mapper.one"},sqlSessionTemplateRef = "sqlSessionTemplateOne")
public class DruidOneConfig {
    private static final Logger LOGGER = LoggerFactory.getLogger(DruidOneConfig.class) ;
    @Resource
    private DruidOneParam druidOneParam ;
    @Bean("dataSourceOne")
    public DataSource dataSourceOne () {
        DruidDataSource datasource = new DruidDataSource();
        datasource.setUrl(druidOneParam.getDbUrl());
        datasource.setUsername(druidOneParam.getUsername());
        datasource.setPassword(druidOneParam.getPassword());
        datasource.setDriverClassName(druidOneParam.getDriverClassName());
        datasource.setInitialSize(druidOneParam.getInitialSize());
        datasource.setMinIdle(druidOneParam.getMinIdle());
        datasource.setMaxActive(druidOneParam.getMaxActive());
        datasource.setMaxWait(druidOneParam.getMaxWait());
        datasource.setTimeBetweenEvictionRunsMillis(druidOneParam.getTimeBetweenEvictionRunsMillis());
        datasource.setMinEvictableIdleTimeMillis(druidOneParam.getMinEvictableIdleTimeMillis());
        datasource.setMaxEvictableIdleTimeMillis(druidOneParam.getMaxEvictableIdleTimeMillis());
        datasource.setValidationQuery(druidOneParam.getValidationQuery());
        datasource.setTestWhileIdle(druidOneParam.isTestWhileIdle());
        datasource.setTestOnBorrow(druidOneParam.isTestOnBorrow());
        datasource.setTestOnReturn(druidOneParam.isTestOnReturn());
        datasource.setPoolPreparedStatements(druidOneParam.isPoolPreparedStatements());
        datasource.setMaxPoolPreparedStatementPerConnectionSize(druidOneParam.getMaxPoolPreparedStatementPerConnectionSize());
        try {
            datasource.setFilters(druidOneParam.getFilters());
        } catch (Exception e) {
            LOGGER.error("druid configuration initialization filter", e);
        }
        datasource.setConnectionProperties(druidOneParam.getConnectionProperties());
        return datasource;
    }
    @Bean
    public SqlSessionFactory sqlSessionFactoryOne() throws Exception{
        SqlSessionFactoryBean factory = new SqlSessionFactoryBean();
        ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
        factory.setDataSource(dataSourceOne());
        factory.setMapperLocations(resolver.getResources("classpath*:/dataOneMapper/*.xml"));
        return factory.getObject();
    }
    @Bean(name="transactionManagerOne")
    public DataSourceTransactionManager transactionManagerOne(){
        return  new DataSourceTransactionManager(dataSourceOne());
    }
    @Bean(name = "sqlSessionTemplateOne")
    public SqlSessionTemplate sqlSessionTemplateOne() throws Exception {
        return new SqlSessionTemplate(sqlSessionFactoryOne());
    }
}

注意事项

• MapperScan 在指定数据源上配置;
• SqlSessionFactory 配置扫描的Mapper.xml地址 ;
• DataSourceTransactionManager 配置该数据源的事务;
• 两个数据源的配置手法相同，不赘述 ;

5、操作案例

• 数据源一：简单查询

  @Service public class AdminUserServiceImpl implements AdminUserService { @Resource private AdminUserMapper adminUserMapper ; @Override public AdminUser selectByPrimaryKey (Integer id) { return adminUserMapper.selectByPrimaryKey(id) ; } }

• 数据源二：事务操作

  @Service public class UserBaseServiceImpl implements UserBaseService { @Resource private UserBaseMapper userBaseMapper ; @Override public UserBase selectByPrimaryKey(Integer id) { return userBaseMapper.selectByPrimaryKey(id); } // 使用指定数据源的事务 @Transactional(value = "transactionManagerTwo") @Override public void insert(UserBase record) { // 这里数据写入失败 userBaseMapper.insert(record) ; // int i = 1/0 ; } }

注意：这里的需要指定该数据源配置的事务管理器。

三、MybatisPlus案例

1、核心依赖

<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.0.7.1</version>
    <exclusions>
        <exclusion>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-generator</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus</artifactId>
    <version>3.0.7.1</version>
</dependency>

2、配置文件

mybatis-plus:
  mapper-locations: classpath*:/mapper/*.xml
  typeAliasesPackage: com.digital.market.*.entity
  global-config:
    db-config:
      id-type: AUTO
      field-strategy: NOT_NULL
      logic-delete-value: -1
      logic-not-delete-value: 0
    banner: false
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
    map-underscore-to-camel-case: true
    cache-enabled: false
    call-setters-on-nulls: true
    jdbc-type-for-null: 'null'

3、分层配置

mapper层
UserBaseMapper extends BaseMapper<UserBase>
实现层
UserBaseServiceImpl extends ServiceImpl<UserBaseMapper,UserBase> implements UserBaseService
接口层
UserBaseService extends IService<UserBase>

4、mapper.xml文件

<mapper namespace="com.plus.batis.mapper.UserBaseMapper" >
  <resultMap id="BaseResultMap" type="com.plus.batis.entity.UserBase" >
    <id column="id" property="id" jdbcType="INTEGER" />
    <result column="user_name" property="userName" jdbcType="VARCHAR" />
    <result column="pass_word" property="passWord" jdbcType="VARCHAR" />
    <result column="phone" property="phone" jdbcType="VARCHAR" />
    <result column="email" property="email" jdbcType="VARCHAR" />
    <result column="create_time" property="createTime" jdbcType="TIMESTAMP" />
    <result column="update_time" property="updateTime" jdbcType="TIMESTAMP" />
    <result column="state" property="state" jdbcType="INTEGER" />
  </resultMap>
  <sql id="Base_Column_List" >
    id, user_name, pass_word, phone, email, create_time, update_time, state
  </sql>
  <select id="selectByParam" parameterType="com.plus.batis.entity.QueryParam" resultMap="BaseResultMap">
    select * from hc_user_base
  </select>
</mapper>

注意事项

BaseMapper中的方法都已默认实现；这里也可以自定义实现一些自己的方法。

5、演示接口

@RestController
@RequestMapping("/user")
public class UserBaseController {
    private static final Logger LOGGER = LoggerFactory.getLogger(UserBaseController.class) ;
    @Resource
    private UserBaseService userBaseService ;
    @RequestMapping("/info")
    public UserBase getUserBase (){
        return userBaseService.getById(1) ;
    }
    @RequestMapping("/queryInfo")
    public String queryInfo (){
        UserBase userBase1 = userBaseService.getOne(new QueryWrapper<UserBase>().orderByDesc("create_time")) ;
        LOGGER.info("倒叙取值：{}",userBase1.getUserName());
        Integer count = userBaseService.count() ;
        LOGGER.info("查询总数：{}",count);
        UserBase userBase2 = new UserBase() ;
        userBase2.setId(1);
        userBase2.setUserName("spring");
        boolean resFlag = userBaseService.saveOrUpdate(userBase2) ;
        LOGGER.info("保存更新：{}",resFlag);
        Map<String, Object> listByMap = new HashMap<>() ;
        listByMap.put("state","0") ;
        Collection<UserBase> listMap = userBaseService.listByMap(listByMap) ;
        LOGGER.info("ListByMap查询：{}",listMap);
        boolean removeFlag = userBaseService.removeById(3) ;
        LOGGER.info("删除数据：{}",removeFlag);
        return "success" ;
    }
    @RequestMapping("/queryPage")
    public IPage<UserBase> queryPage (){
        QueryParam param = new QueryParam() ;
        param.setPage(1);
        param.setPageSize(10);
        param.setUserName("cicada");
        param.setState(0);
        return userBaseService.queryPage(param) ;
    }
    @RequestMapping("/pageHelper")
    public PageInfo<UserBase> pageHelper (){
        return userBaseService.pageHelper(new QueryParam()) ;
    }
}

这里pageHelper方法是使用PageHelper插件自定义的方法。

四、源代码地址

GitHub·地址
https://github.com/cicadasmile/middle-ware-parent
GitEE·地址
https://gitee.com/cicadasmile/middle-ware-parent