关于在idea中mybatis的配置

关于在idea中mybatis的配置

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首先是pom文件导入坐标

 <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
            <scope>test</scope>
        </dependency>


<!--        mysql-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.21</version>
        </dependency>

 <!--        mybatis-->
 <dependency>
   <groupId>org.mybatis</groupId>
   <artifactId>mybatis</artifactId>
   <version>3.4.5</version>
 </dependency>

        <!-- https://mvnrepository.com/artifact/org.apache.ibatis/ibatis-core -->
        <dependency>
            <groupId>org.apache.ibatis</groupId>
            <artifactId>ibatis-core</artifactId>
            <version>3.0</version>
        </dependency>

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.5</version>
        </dependency>

然后是reources中创建一个xml文件   配置如下

<?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>
<!--配置环境-->
    <environments default="development">
        <environment id="development">
<!--            事务管理  默认用jdbc-->
            <transactionManager type="JDBC"></transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useUnicode=true&amp;characterEncoding=utf-8&amp;serverTimezone=UTC"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>

        </environment>
    </environments>

    <mappers>
        <mapper resource="com/controller/dao/UserMapper.xml"/>
    </mappers>
    
</configuration>

工具类 获取sqlSessionFactory对象

package com.controller.utils;


import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;

public class MybatisUtils {

    private static SqlSessionFactory sqlSessionFactory;

    static {
        try {
            String resource = "mybatis-config.xml";
            Reader inputStream = Resources.getResourceAsReader(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    //获取SqlSession连接
    public static SqlSession getSession(){
        return sqlSessionFactory.openSession();
    }

}

注意所在的位置 

对数据库进行查询  包内的 xml文件的配置

<?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.controller.dao.Userd">

<!--select查询语句-->
    <select id="getList" resultType="com.controller.pojo.User">
        select * from mybatis.user

    </select>

</mapper>

关于几个常见的错误点：

1.pom.xml文件中 一定要导入

<dependency>
    <groupId>org.apache.ibatis</groupId>
    <artifactId>ibatis-core</artifactId>
    <version>3.0</version>
</dependency>

要不然ibatis包会查找不到

在pom.xml文件中 的<build></build>中 要添加过滤

<resources>
    <resource>
        <directory>src/main/java</directory>
        <includes>
            <include>**/*.properties</include>
            <include>**/*.xml</include>
        </includes>
        <filtering>false</filtering>
    </resource>
    <resource>
        <directory>src/main/resources</directory>
        <includes>
            <include>**/*.properties</include>
            <include>**/*.xml</include>
        </includes>
        <filtering>false</filtering>
    </resource>
</resources>

2.关于连接sqlsession的类中，inputStream 在build方法中 不能用  使用 Reader 就不报错了

public class MybatisUtils {

    private static SqlSessionFactory sqlSessionFactory;

    static {
        try {
            String resource = "mybatis.xml";
            Reader inputStream = Resources.getResourceAsReader(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    //获取SqlSession连接
    public static SqlSession getSession(){
        return sqlSessionFactory.openSession();
    }

}