【MyBatis】Mybatis使用SqlSessionFactory加载xml文件

1.概述

MyBatis框架主要是围绕着SqlSessionFactory这个类进行的，这个的创建过程如下：

1. 定义一个Configuration对象，其中包含数据源、事务、mapper文件资源以及影响数据库行为属性设置settings
2. 通过配置对象，则可以创建一个SqlSessionFactoryBuilder对象
3. 通过 SqlSessionFactoryBuilder 获得SqlSessionFactory 的实例。
4. SqlSessionFactory 的实例可以获得操作数据的SqlSession实例，通过这个实例对数据库进行操作

2.案例

案例结构如下

只需要看红色框框的就可以了。

2.1 数据源配置

位置：/Users/lcc/IdeaProjects/lcc_work/test-flink/flink-v110-myibatis-demo/src/main/resources/mybatis-config-person.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <settings>
        <!-- 打印查询语句 -->
        <setting name="logImpl" value="STDOUT_LOGGING" />
    </settings>

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/><!-- 单独使用时配置成MANAGED没有事务 -->
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="${jdbc.password}"/>
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <mapper resource="mybatis/PersonMapper.xml"/>
    </mappers>

</configuration>

然后我们要写一个mapppr类主要用来查询的。

package com.flink.myibatis.mapper;

import com.flink.myibatis.entity.Person;
import org.apache.ibatis.annotations.Mapper;

import java.util.List;
import java.util.Map;

@Mapper
public interface PersonMapper {
    List<Map<String,Object>> listAll();
}

最后配置mapper

<?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.flink.myibatis.mapper.PersonMapper">



    <select id="listAll"  resultType="java.util.Map">
      SELECT * from db
    </select>


</mapper>

这里很简单，但是要注意namespace不要写错了，然后我们写测试类

package com.flink.myibatis.utils;

import com.flink.myibatis.mapper.PersonMapper;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;

import java.io.*;
import java.util.List;
import java.util.Map;
import java.util.Properties;

import static org.junit.Assert.*;

public class MybatisSessionFactoryTest {

    @Test
    public void mainTest() throws FileNotFoundException {
        Properties properties = new Properties();
        properties.setProperty("jdbc.driver","com.mysql.jdbc.Driver");
//        properties.setProperty("jdbc.url","jdbc:mysql://localhost:3306/mysql_monitor?useUnicode=true&characterEncoding=utf-8&useSSL=true");
        properties.setProperty("jdbc.url","jdbc:mysql://localhost:3306/mysql_monitor");
        properties.setProperty("jdbc.username","root");
        properties.setProperty("jdbc.password","12345678");

        File file = new File("/Users/lcc/IdeaProjects/lcc_work/test-flink/flink-v110-myibatis-demo/src/main/resources/mybatis-config-person.xml");
        InputStream mybatis = new FileInputStream(file);
        SqlSessionFactory session = new SqlSessionFactoryBuilder().build(mybatis,properties);
        SqlSession sqlSession = session.openSession();

        PersonMapper personMapper = sqlSession.getMapper(PersonMapper.class);
        List<Map<String, Object>> persons = personMapper.listAll();

        System.out.println(persons);

    }

}

运行结果如下，可以看到查询到了数据

Opening JDBC Connection
Created connection 1470344997.
Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@57a3af25]
==>  Preparing: SELECT * from db 
==> Parameters: 
<==    Columns: id, name, ip, username, password, database, port, status
<==        Row: 26, lcc, localhost, root, 12345678, house, 3306, null
<==      Total: 1
[{password=12345678, database=house, port=3306, ip=localhost, name=lcc, id=26, username=root}]

但是这里有个坑

//        properties.setProperty("jdbc.url","jdbc:mysql://localhost:3306/mysql_monitor?useUnicode=true&characterEncoding=utf-8&useSSL=true");
        properties.setProperty("jdbc.url","jdbc:mysql://localhost:3306/mysql_monitor");

url只能写到库信息，再写多了就会报错mysql连接不上

报错参考：MySQL : mysql连接报 Communications link failure

参考：MyBatis执行SQL的两种方式：SqlSession和Mapper接口

参考：MyBatis的通俗理解：SqlSession.getMapper()源码分析

参考：MyBatis SqlSessionFactory的几种常见创建方式

参考：MyBatis常用对象SqlSessionFactory和SqlSession介绍和运用

本文地址：https://blog.csdn.net/qq_21383435/article/details/107424258