1.Mybatis-快速使用

1.创建一个maven项目



2.在pom.xml中添加依赖

    <!--导入依赖-->
    <dependencies>
        <!--mysql驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
          <version>8.0.13</version>
        </dependency>

        <!--mybatis-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.1</version>
        </dependency>

        <!--junit-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
    </dependencies>

    <!--在build中配置resources,来防止我们资源导出失败的问题-->
    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties
                    **/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
            <resource>
                <directory>src/main/resources</directory>
                <includes>
                    <include>**/*.properties
                    **/*.xml</include>
                </includes>
                <filtering>false</filtering>
            </resource>
        </resources>
    </build>

3.在resources文件下添加mybatis-config.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.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?serverTimezone=GMT%2B8&useSSL=true&useUnicode=true&characterEncoding=utf8"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>

    <!--每一个Mapper.XML都需要在Mybatis核心配置文件中注册-->
    <mappers>
        <mapper resource="com/hua/dao/UserMapper.XML"/>
    </mappers>

</configuration>

4.创建基本目录结构（dao,pojo,utils）

5.在pojo下创建一个实体类User

package com.hua.pojo;

public class User {
    private int id;
    private String name;
    private String pwd;


    public User() {
    }

    public User(int id, String name, String pwd) {
        this.id = id;
        this.name = name;
        this.pwd = pwd;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPwd() {
        return pwd;
    }

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

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

6.在dao下创建一个接口UserDao

package com.hua.dao;

import com.hua.pojo.User;

import java.util.List;

public interface UserDao {
    //查询全部用户
    List<User> getUserList();

    //根据id查询用户
    User getUserById(int id);

    //插入一个用户
    int addUser(User user);

    //修改用户
    int updateUser(User user);

    //删除一个用户
    int deleteUser(int id);


}

7.在dao下创建一个UserMapper.xml

<?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-->
<mapper namespace="com.hua.dao.UserDao">

    <!--select查询语句-->
    <select id="getUserList" resultType="com.hua.pojo.User">
     select * from user
    </select>

    <select id="getUserById" parameterType="int" resultType="com.hua.pojo.User">
        select * from user where id = #{id}
    </select>

    <!--对象中的属性可以直接取出来-->
    <insert id="addUser" parameterType="com.hua.pojo.User" >
        insert into user(id,name,pwd) values (#{id},#{name},#{pwd})
    </insert>

    <update id="updateUser" parameterType="com.hua.pojo.User">
        update user set name = #{name},pwd = #{pwd}  where id = #{id}
    </update>

    <delete id="deleteUser" parameterType="int" >
        delete from user where id = #{id}
    </delete>
</mapper>

8.在utils文件下添加工具类MybatisUtils

package com.hua.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;

//sqlSessionFactory --> sqlSession
public class MybatisUtils {

    private static SqlSessionFactory sqlSessionFactory;

    static {

        try {
            //使用Mybatis第一步：获取sqlSessionFactory 对象
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        }catch (IOException e){
           e.printStackTrace();
        }
    }


    public static SqlSession getSqlSession(){
        return sqlSessionFactory.openSession(true);

    }

}

9.在MySQL数据库中创建名为mybatis的数据库，并创建一张名为user的表，再添加如下字段。手动添加数据进去便于之后的测试！

10.在test/java下创建测试类MybatisTest进行测试

import com.hua.dao.UserDao;
import com.hua.pojo.User;
import com.hua.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class MybatisTest {

    @Test
    public void getUserListTest(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserDao mapper = sqlSession.getMapper(UserDao.class);

        List<User> userList = mapper.getUserList();

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

    @Test
    public void getUserByIdTest(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserDao mapper = sqlSession.getMapper(UserDao.class);

        User user = mapper.getUserById(8);
        System.out.println(user);

        sqlSession.close();
    }

    @Test
    public void addUserTest(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserDao mapper = sqlSession.getMapper(UserDao.class);

        mapper.addUser(new User(9,"账号","密码"));

        sqlSession.close();
    }

    @Test
    public void updateUserTest(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserDao mapper = sqlSession.getMapper(UserDao.class);

        mapper.updateUser(new User(9,"accountNumber","123456"));

        sqlSession.close();
    }

    @Test
    public void deleteUserTest(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserDao mapper = sqlSession.getMapper(UserDao.class);

        mapper.deleteUser(9);

        sqlSession.close();
    }
}