Spring整合Mybatis

Mybatis是一个半ORM（对象关系映射）框架，它内部封装了JDBC，开发时只需要关注Sql语句本身，不需要花费精力去处理加载驱动，创建链接，创建statement等繁杂的过程，程序元直接编写原生态sql，可以严格控制sql执行性能，灵活度高。

Mybatis可以使用XML或者注释来配置和映射原生信息，将POJO映射成数据库中的记录，避免了几乎所有的JDBC代码和手动设置参数以及获取结果集。

通过XML文件或注释的方式将要执行的各种statement配置起来，并通过java对象和statement中sql的动态参数进行映射生成最终执行的sql语句，最后由mybatis框架执行sql并将结果映射为java对象并返回

1.导入 mybatis 等依赖

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.10.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.6</version>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.16</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.2.10.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>1.3.0</version>
        </dependency>

2.新建配置文件

resources/jdbc.properties

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/spring?useSSL=false
jdbc.username=root
jdbc.password=123456

3.新建 Account 实体类

package com.bdbk.domain;

public class Account {

    private Integer id;
    private String name;

    @Override
    public String toString() {
        return "Account{" +
                "id=" + id +
                ",name='" + name + '\'' +
                '}';
    }
}

4.新建 AccountDao 接口

package com.bdbk.dao;

import com.bdbk.domain.Account;
import org.apache.ibatis.annotations.Select;

import java.util.List;

public interface AccountDao {
    @Select("select * from account where id = #{id}")
    public Account findById(Integer id);
}

5.新建 JdbcConfig 配置类

package com.bdbk.config;

import com.alibaba.druid.pool.DruidDataSource;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import javax.sql.DataSource;

public class JdbcConfig {

    @Value("${jdbc.driver}")
    private String driver;
    @Value("${jdbc.url}")
    private String url;
    @Value("${jdbc.username}")
    private String username;
    @Value("${jdbc.password}")
    private String password;

    @Bean
    public DataSource dataSource(){
        DruidDataSource ds = new DruidDataSource();
        ds.setDriverClassName(driver);
        ds.setUrl(url);
        ds.setUsername(username);
        ds.setPassword(password);
        return ds;
    }
}

6.新建 MybatisConfig 配置类

package com.bdbk.config;

import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.mapper.MapperScannerConfigurer;
import org.springframework.context.annotation.Bean;

import javax.sql.DataSource;

public class MybatisConfig {
    @Bean
    public SqlSessionFactoryBean sqlSessionFactoryBean(DataSource dataSource){
        SqlSessionFactoryBean ssfb = new SqlSessionFactoryBean();
        ssfb.setTypeAliasesPackage("com.bdbk.domain");
        ssfb.setDataSource(dataSource);
        return ssfb;
    }
    @Bean
    public MapperScannerConfigurer mapperScannerConfigurer(){
        MapperScannerConfigurer msc = new MapperScannerConfigurer();
        msc.setBasePackage("com.bdbk.dao");
        return msc;
    }
}

7.新建 SpringConfig 配置类

package com.bdbk.config;


import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.context.annotation.PropertySource;

@Configuration
@ComponentScan("com.bdbk") //配置扫描位置
@PropertySource("classpath:jdbc.properties") //加载配置文件
@Import({JdbcConfig.class, MybatisConfig.class}) //导入两个配置类
public class SpringConfig {
}

8.新建 AccountService 及实现类

package com.bdbk.service.impl;

import com.bdbk.dao.AccountDao;
import com.bdbk.domain.Account;
import com.bdbk.service.AccountService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class AccountServiceImpl implements AccountService {
    @Autowired
    private AccountDao accountDao;

    @Override
    public Account findById(Integer id) {
        return accountDao.findById(id);
    }
}

9.新建 App 启动类

public class App {
    public static void main(String[] args){
        ApplicationContext context = new AnnotationConfigApplicationContext(SpringConfig.class);
        AccountService accountService = context.getBean(AccountService.class);
        Account account = accountService.findById(2);
        System.out.println(account);
    }
}

运行结果