创建Maven工程

• 数据库另一个文章的、点击进入

• 目录结构如图所示

  • 在resources中创建包的时候，不要直接创建com.config.xml, 正确方式应该是：　com/config/xml

• pow.xml的配置、　点击进入

• 使用注解方式，不需要创建Mapper.xml, 忘了删除了...

• 实体类User.java

package cn.lacknb.beans;

public class User {

    private String uname;
    private String usex;
    private Integer uid;

    public String getUname() {
        return uname;
    }

    public void setUname(String uname) {
        this.uname = uname;
    }

    public String getUsex() {
        return usex;
    }

    public void setUsex(String usex) {
        this.usex = usex;
    }

    public Integer getUid() {
        return uid;
    }

    public void setUid(Integer uid) {
        this.uid = uid;
    }

    @Override
    public String toString() {
        return "User{" +
                "uname='" + uname + '\'' +
                ", usex='" + usex + '\'' +
                ", uid=" + uid +
                '}';
    }
}

• 创建接口IUserDao.java

package cn.lacknb.dao;

import cn.lacknb.beans.User;
import org.apache.ibatis.annotations.Select;

import java.util.List;

public interface IUserDao {

    @Select("select * from user")
    List<User> findAll();
}

• 创建测试类

package cn.lacknb.mybatis02;

import cn.lacknb.beans.User;
import cn.lacknb.dao.IUserDao;
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.util.List;

public class MapperTest {

    public static void main(String[] args) throws IOException {

        // 读取配置文件
        InputStream config = Resources.getResourceAsStream("com/config/xml/mybatis-config.xml");
        // 创建SqlSessionFactory
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory factory = builder.build(config);
        // 使用工厂类生产SqlSession对象
        SqlSession session = factory.openSession();
        // 使用Sqlsession创建Dao接口的代理对象
        IUserDao dao = session.getMapper(IUserDao.class);
        // 使用代理对象执行方法
        List<User> users = dao.findAll();
        for (User user: users){
            System.out.println(user);
        }
        session.close();
        config.close();

    }
}

• mybatis-config.xml文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">

<configuration>
    <!--    配置环境-->
    <environments default="development">
<!--       配置mysql的环境， 和default保持一致-->
        <environment id="development">
<!--           配置事务的类型　ＪＤＢＣ  -->
            <transactionManager type="JDBC"/>
<!--            配置数据源（连接池）-->
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf8"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!--        映射文件的位置-->
<!--        <mapper resource="com/config/xml/Mapper.xml"/>-->
<!--        使用注解的方式-->
        <mapper class="cn.lacknb.dao.IUserDao"/>
    </mappers>


</configuration>

• 显示日志文件log4j.properties

# global logging configuration
log4j.rootLogger=ERROR, stdout
# Mybatis logging configuration...
# 将包com.mybatis下的日志等级设为DEBUG
log4j.logger.com.mybatis=DEBUG
# Console output ...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout

log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n