Mybatis入门

学习目标：入门SSM框架进阶

第一个Mybatis程序

---

学习内容：Mybatis入门

环境
1、 IDEA
2、 Maven
3、MySQL5.7
4、 Mybatis

---

学习产出：

目录结构：

1.idea创建简单maven工程创建

2.pom.xml导入依赖

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>alphatest</artifactId>
    <version>1.0-SNAPSHOT</version>
<!--导入依赖-->

    <dependencies>
        <!--mysql驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.38</version>
        </dependency>
        <!--        mybatis驱动-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.2</version>
        </dependency>
        <!--        junit-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>

    </dependencies>
</project>

 

 

3.编写MyBatis核心配置文件

<?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">
<!--核心配置文件-->
<configuration>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/alpha?useSSL=true&amp;useUnicode=true&amp;characterEncoding=utf8"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
<!--#####注意resource改为mapper xml文件位置-->
    <mappers>
        <mapper resource="com/kuang/dao/userMapper.xml"/>
    </mappers>
</configuration>

 

4.编写mybatis工具类

 

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;

public class mybatisUtils {
//  获取SqlssionFactory  
    private static SqlSessionFactory sqlSessionFactory;
    static {
        try {
            String resource = "mybatisConfig.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

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

5.创建实体类

 

package cn.alpha.pojo;
//实体类
public class User {
    private int uid;
    private String unmae,upwd;
    
    @Override
    public String toString() {
        return "User{" +
                "uid=" + uid +
                ", unmae='" + unmae + '\'' +
                ", upwd='" + upwd + '\'' +
                '}';
    }
    public User() {
    }

    public User(int uid, String unmae, String upwd) {
        this.uid = uid;
        this.unmae = unmae;
        this.upwd = upwd;
    }
    public void setUid(int uid) {
        this.uid = uid;
    }

    public void setUnmae(String unmae) {
        this.unmae = unmae;
    }

    public void setUpwd(String upwd) {
        this.upwd = upwd;
    }

    public int getUid() {
        return uid;
    }

    public String getUnmae() {
        return unmae;
    }

    public String getUpwd() {
        return upwd;
    }

}

 

6.创建mapper接口；

 

import java.util.List;
//mapper接口
public interface UserDao {
    List<User>getUserList();
}

 

7.编写XMl文件

<?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">

<!--namespace定位mapper接口-->
<mapper namespace="cn.alpha.dao.UserDao">
<!--    查询语句-->
<!--    一个名为 “select” 的映射语句，-->
    <select id="select" >

    select * from alpha.user ;

    </select>
</mapper>

8.测试Test

 

import cn.alpha.dao.UserDao;
import cn.alpha.pojo.User;
import cn.alpha.utils.mybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Before;
import org.junit.Test;

import java.util.List;

public class UserTest {

    @Test

    public void  test(){

//        获取sqlssion对象
        SqlSession sqlSession= mybatisUtils.getSession();
//     方法一: getmapper
        UserDao userDao=sqlSession.getMapper(UserDao.class);
        List<User> userList= userDao.getUserList();
       //输出结果
        for (User user:userList){
            System.out.println(user);
        }
        sqlSession.close();
    }

}

****遇见问题，maven 资源导出问题；
<build>
        <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>
    </build>