mybatis实现简单的增删改查

1.创建项目

然后next，finally。

2.打开pom.xml引入配置文件

在原有代码的下方插入以下代码

<packaging>jar</packaging>

    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.3</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.18</version>
        </dependency>
        <!-- 导入日志坐标-->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.12</version>
        </dependency>
        <!--导入单元测试坐标-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.10</version>
        </dependency>
    </dependencies>

3.引入log4j.propertise

创建该类型的文件，在网上找到代码粘进去

4.创建实体类以及持久层接口

简单的用户信息为例
User.java

public class User implements Serializable {
    private Integer id;
    private String username;
    private Date birthday;
    private String sex;
    private String address;

    public Integer getId() {
        return id;
    }

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

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", birthday=" + birthday +
                ", sex='" + sex + '\'' +
                ", address='" + address + '\'' +
                '}';
    }
}

UserDao.java

public interface UserDao {
    //查询所有用户
    List<User> findAll();
    //保存用户
    void saveUser(User user);
    //用户的更新操作
    void updateUser(User user);
    //根据id删除用户
    void deleteUser(Integer id);
    //根据id查询
    User findById(Integer id);
    //根据用户名称模糊查询用户信息
    List<User> findByName(String username);
    //查询总记录条数
    Integer findTotal();
    //根据queryVo中的条件查询用户
    List<User> findUserByVo(QueryVo vo);
}

5.配置mybatis主配置文件SqlMapConfig.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">
<!--mybatis得主配置文件 -->
<configuration>
    <!--配置环境-->
    <environments default="mysql">
        <!-- 配置mysql的环境-->
        <environment id="mysql">
            <!-- 配置事务类型-->
            <transactionManager type="JDBC"></transactionManager>
            <!-- 配置数据连接池-->
            <dataSource type="POOLED">
                <!-- 配置连接数据库的基本信息-->
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/dream?serverTimezone=UTC"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>

    <!-- 指定映射配置文件位置，映射配置文件指的是每个dao独立的配置文件-->
    <mappers>
        <mapper resource="com/bian/dao/UserDao.xml"/>
    </mappers>
</configuration>

6.在resources目录下创建UserDao.xml

用来写明每个功能实现需要用的Sql语句以及返回类型，所在位置
具体代码如下

<?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.bian.dao.UserDao">
    <!--配置查询所有 -->
    <select id="findAll" resultType="com.bian.domain.User">
        select * from user;
    </select>
    <!--配置保存用户 -->
    <insert id="saveUser" parameterType="com.bian.domain.User">
        <selectKey keyProperty="id" keyColumn="id" resultType="int" order="AFTER">
            select  last_insert_id();
        </selectKey>
        insert into user(username,address,sex,birthday)values(#{username},#{address},#{sex},#{birthday});
    </insert>
    <update id="updateUser" parameterType="com.bian.domain.User">
        update user set username=#{username},address=#{address},sex=#{sex},birthday=#{birthday} where id=#{id};
    </update>
    <delete id="deleteUser" parameterType="java.lang.Integer">
        delete from user where id=#{uid};
    </delete>
    <select id="findById" parameterType="java.lang.Integer" resultType="com.bian.domain.User">
        select * from user where id = #{aaa};
    </select>
    <select id="findByName" parameterType="string" resultType="com.bian.domain.User">
        select * from user where username like #{name}
    </select>
    <select id="findTotal" resultType="java.lang.Integer">
        select count(id) from user;
    </select>
    <!-- 根据queryVo的条件查询用户-->
    <select id="findUserByVo" parameterType="com.bian.domain.QueryVo" resultType="com.bian.domain.User">
        select * from user where username like #{user.username}
    </select>
</mapper>

7.编写测试类

package com.bian.text;

import com.bian.dao.UserDao;
import com.bian.domain.QueryVo;
import com.bian.domain.User;
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 org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.InputStream;
import java.util.Date;
import java.util.List;

public class MybatisText {

    private InputStream in;
    private SqlSession session;
    private UserDao userDao;

    @Before
    public void init() throws Exception{
        //1读取配置文件
        in = Resources.getResourceAsStream("sqlMapConfig.xml");
        //2.创建SqlSessionFactory工厂
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory factory = builder.build(in);
        //3.使用工厂生产SqlSession对象
        //构建者模式，把对象的创建过程隐藏，使用者只调用方法就可以拿到对象。降低类之间的依赖
        session = factory.openSession();
        //4.使用SqlSession创建Dao接口的代理对象

        userDao = session.getMapper(UserDao.class);
    }
    @After
    public void destroy() throws Exception{
        //提交事务
        session.commit();
        //6.释放资源
        session.close();
        in.close();
    }
    @Test
    public void textFindAll(){

        //5.使用代理对象执行方法
        List<User> users = userDao.findAll();
        for(User user:users){
            System.out.println(user);
        }

    }
    @Test
    public void textSave(){
        User user = new User();
        user.setUsername("name");
        user.setAddress("address");
        user.setSex("sex");
        user.setBirthday(new Date());
        System.out.println(user);
        //5.使用代理对象执行方法
        userDao.saveUser(user);
        System.out.println(user);
    }

    @Test
    public void textUpdate(){
        User user = new User();
        user.setId(1);
        user.setUsername("name");
        user.setAddress("address");
        user.setSex("sex");
        user.setBirthday(new Date());
        //5.使用代理对象执行方法
        userDao.updateUser(user);
    }

    @Test
    public void textDelete(){
        userDao.deleteUser(1);
    }

    @Test
    public void textFindById(){
        User user = userDao.findById(1);
        System.out.println(user);
    }

    @Test
    public void textFindByName(){
        List<User> users = userDao.findByName("%n%");
        for(User user:users){
            System.out.println(user);
        }
    }

    @Test
    public void textFindTotal(){
        Integer count = userDao.findTotal();
        System.out.println("总用户量为"+count);
    }

    @Test
    public void textFindByVo(){
        QueryVo vo = new QueryVo();
        User user = new User();
        user.setUsername("%n%");
        vo.setUser(user);
        List<User> users = userDao.findUserByVo(vo);
        for(User u:users){
            System.out.println(u);
        }
    }
}

目录截图