笔记：mybatis javaConfig配置

在spring/springboot中使用mybatis时，只需要填写mybatis依赖，数据库配置以及相关mybatis配置信息，重写下sqlSessionFactory就可以使用了。但是在不使用spring的项目中怎么使用纯javaConfig配置mybatis，之前没有遇到过，这次做下记录。

众所周知，方法的使用都是实例调用或者静态类方法调用。这里其实和Spring相同，只不过spring是它创建管理了SqlSessionFactory的bean。这里还是写一个方法去获得SqlSessionFactory，在SqlSessionFactory中需要配置PooledDataSource相关数据，在mybatis配置中需要定义有哪些mapper，之后才能在这些mapper中获取相关方法。

public class MybatisUtils {
    private static SqlSessionFactory sqlSessionFactory;
  
    public static SqlSessionFactory initSqlSessionFactory(DBConfigInfo dbConfiguration) {
        if (sqlSessionFactory == null) {
           //这里是配置jdbc的相关配置
            PooledDataSource pooledDataSource = new PooledDataSource();
            pooledDataSource.setDriver("com.mysql.jdbc.Driver");
            pooledDataSource.setUrl(dbConfiguration.getUrl());
            pooledDataSource.setUsername(dbConfiguration.getUserName());
            pooledDataSource.setPassword(dbConfiguration.getUserPassword());
      
            TransactionFactory transactionFactory = new JdbcTransactionFactory();
            Environment environment = new Environment("development", transactionFactory, pooledDataSource);

            Configuration configuration = new Configuration(environment);
      //配置驼峰法映射属性字段
            configuration.setMapUnderscoreToCamelCase(true);
      //这里是初始化了一部分系统定义的别名
            configuration.getTypeAliasRegistry().registerAlias("student", Student.class);
      //这里是添加扫描的Mapper文件
            configuration.addMapper(StudentMapper.class);
      //构建相应的sqlSessionFactory
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(configuration);
        }
        return sqlSessionFactory;
    }
}

在获取到sqlSessionFactory后则需要获取对应的SqlSession

public static SqlSession getSession(){
        if (sqlSessionFactory == null){
            DBConfiguration dBConfiguration = DBConfiguration.getInstance();
            initSqlSessionFactory(dBConfiguration.getConfigInfo());
        }
        return sqlSessionFactory.openSession();
    }

从SqlSession中获取相应的Mapper使用Mapper中的方法。

        SqlSession  sqlSession = MybatisUtils.getSession();
    StudentMapper mapper = sqlSession.getMapper(StudentMapper.class);
    List students = mapper.selectAll();
    sqlSession.commit();
    sqlSession.close();

对应的StudentMapper

public interface StudentMapper {

    @Select("select * from student")
    List selectAll();
}

参考链接