MyBatis_自定义工具类简化创建SqlSession过程

主要内容

1、创建自定义工具类: 用于获取SqlSession对象简化使用流程
2、使用自定义工具类,完成sql操作

1. 创建自定义工具类

创建自定义工具类MyBatisUtils.java

package com.bipowernode.utils;
/**
 *  自定义工具类
 */
public class MyBatisUtils {
    // 当加载当前类,就执行Static静态中的代码且一次
    // 定义全局的SqlSessionFactory
    private static SqlSessionFactory factory = null;
    static{
        String config = "mybatis.xml";
        try{
            InputStream in = Resources.getResourceAsStream(config);
            // 使用SqlSessionFactoryBuild创建SqlSessionFactory对象
            factory = new SqlSessionFactoryBuilder().build(in);

        }catch(IOException e){
            e.printStackTrace();
        }
    }
    // 定义一个方法,用户获取SqlSession
    public static SqlSession getSqlSession(){
        // 如果存在factory,就创建SqlSession对象
        SqlSession sqlSession = null;
        if (factory !=null){
            sqlSession = factory.openSession(); // 非自动提交事务
        }
        return sqlSession; // 返回sqlSession对象
    }
}

2. 使用自定义工具类

package com.bipowernode;

public class MyApp2 {
    public static void main(String[] args) throws IOException {
        /**
         * 访问mybatis读取student配置文件位置
         */
        // 使用自定义的工具类获取SqlSession对象
        SqlSession sqlSession = MyBatisUtils.getSqlSession();
        String sqlId = "com.bipowernode.dao.StudentDao" + "." + "selectStudents";
        List studentList = sqlSession.selectList(sqlId);
        studentList.forEach(stu -> System.out.println(stu));
        sqlSession.close();
    }
}

说明: 使用工具类封装创建SqlSession对象的过程后,获取SqlSession对象就很简单了,只需一行代码。

控制台输出:

Logging initialized using 'class org.apache.ibatis.logging.stdout.StdOutImpl' adapter.
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
PooledDataSource forcefully closed/removed all connections.
Opening JDBC Connection
Created connection 1604125387.
Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@5f9d02cb]
==>  Preparing: select id ,name email,age from student order by id; 
==> Parameters: 
<==    Columns: id, email, age
<==        Row: 1001, 李四, 20
<==        Row: 1002,  张三, 28
<==        Row: 1003, 张飞, 20
<==        Row: 1004, 刘备, 20
<==      Total: 4
Student{id=1001, name='null', email='李四', age=20}
Student{id=1002, name='null', email=' 张三', age=28}
Student{id=1003, name='null', email='张飞', age=20}
Student{id=1004, name='null', email='刘备', age=20}
Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@5f9d02cb]
Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@5f9d02cb]
Returned connection 1604125387 to pool.

说明: 自定义工具类获取SqlSession对象并执行sql操作完成。