web实习自学Mybatis框架笔记（一）

1. 导入依赖

第一步，在Idea 上创建一个maven项目，接着，在pom.xml上导入依赖，需要用到MySQL驱动，mybits,junit。

<!--导入依赖-->
    <dependencies>
        <!--mysql驱动-->

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.30</version>
        </dependency>

        <!--mybatis-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.3.0</version>
        </dependency>

        <!--junit-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.1</version>
        </dependency>
        
    </dependencies>

创建一个模块

1. 编写mybatis核心配置

在src->main->resources目录下创建一个xml文件，编写如下代码：

<?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>
  <environments default="development">
    <environment id="development">
      <transactionManager type="JDBC"/>
      <dataSource type="POOLED">
        <property name="driver" value="${driver}"/>
        <property name="url" value="${url}"/>
        <property name="username" value="${username}"/>
        <property name="password" value="${password}"/>
      </dataSource>
    </environment>
  </environments>
  <mappers>
    <mapper resource="org/mybatis/example/BlogMapper.xml"/>
  </mappers>
</configuration>

2. 编写工具类

public class MybatisUtils {

    static private SqlSessionFactory sqlSessionFactory;
    static{

        //使用mybatis获取sqlSessionFactory对象
        try {
            String resource = "src/main/resource/mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
             sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    public static SqlSession getSqlSession(){
        SqlSession sqlSession = sqlSessionFactory.openSession();
        return sqlSession;
    }

3. 编写实体类

package com.study.pojo;

public class User {
    private int pid;
    private String pname;
    private String pwd;

    public User() {
    }

    public User(int pid, String pname, String pwd) {
        this.pid = pid;
        this.pname = pname;
        this.pwd = pwd;
    }

    public int getPid() {
        return pid;
    }

    public void setPid(int pid) {
        this.pid = pid;
    }

    public String getPname() {
        return pname;
    }

    public void setPname(String pname) {
        this.pname = pname;
    }

    public String getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

    @Override
    public String toString() {
        return "User{" +
                "pid=" + pid +
                ", pname='" + pname + '\'' +
                ", pwd='" + pwd + '\'' +
                '}';
    }
}

4. 编写接口

package com.study.dao;

import com.study.pojo.User;

import java.util.List;

public interface UserDao {
    
    List<User> getUserList();

}

5. 编写相应的配置文件

<?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=绑定一个对应的dao/mapper接口
全限定类名
-->
<mapper namespace="com.study.dao.UserDao">
    <!--id="对应的接口的名字" 
    返回结果 全限定名
    -->
    <select id="getUserList" resultType="com.study.pojo.User">
    select * from test.people
  </select>
</mapper>

6. 测试

package com.study.dao;

import com.study.pojo.User;
import com.study.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class UserDaoTest {
    @Test
    public void test1(){

        //获得SqlSession对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        //执行SQL语句

        UserDao mapper = sqlSession.getMapper(UserDao.class);
        List<User> userList = mapper.getUserList();

        for (User user : userList) {
            System.out.println(user);
        }

        //关闭
        sqlSession.close();


    }
}