Mybatis入门

Mybatis入门

搭建环境

创建数据库

/*
 Navicat Premium Data Transfer

 Source Server         : localhost
 Source Server Type    : MySQL
 Source Server Version : 50716
 Source Host           : localhost:3306
 Source Schema         : mybatis

 Target Server Type    : MySQL
 Target Server Version : 50716
 File Encoding         : 65001

 Date: 05/09/2020 12:29:50
*/

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for user
-- ----------------------------
DROP TABLE IF EXISTS `user`;
CREATE TABLE `user`  (
  `id` int(8) NOT NULL,
  `name` varchar(20) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

-- ----------------------------
-- Records of user
-- ----------------------------
INSERT INTO `user` VALUES (1, 'zhang');
INSERT INTO `user` VALUES (2, 'wang');
INSERT INTO `user` VALUES (3, 'liu');

SET FOREIGN_KEY_CHECKS = 1;

创建Maven工程

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>

<!--    父工程-->
    <groupId>org.example</groupId>
    <artifactId>MybatisDemo</artifactId>
    <version>1.0-SNAPSHOT</version>

<!--    导入依赖-->
    <dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.5</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
        </dependency>
    </dependencies>
</project>

创建模块

删除默认的src目录,新建maven项目

├─.idea
└─Mybatis1
    └─src
        ├─main
        │  ├─java
        │  └─resources
        └─test
            └─java

编写Mybatis的核心配置文件(resources目录下)

<?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="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=true"/>
                <property name="username" value="root"/>
                <property name="password" value="qwe123"/>
            </dataSource>
        </environment>
    </environments>

  
</configuration>

编写mybatis的工具类

新建一个package,编写工具类代码

package com.ivy.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;

public class MybatisUtils {

    private static SqlSessionFactory sqlSessionFactory;

    static {

        try {
            // 配置文件的路径
            String resource = "mybatis-config.xml";
            InputStream resourceAsStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    public static SqlSession getSqlSessionFactory() {
        return sqlSessionFactory.openSession();
    }
}

创建数据库对应的实体类

package com.ivy.pojo;

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

    public User() {
    }

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

    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;
    }

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

创建接口类

package com.ivy.dao;

import com.ivy.pojo.User;

import java.util.List;

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

创建mapper的配置文件

放在resources目录下可以跳过一些资源过滤的坑

<?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写上接口类的类路径-->
<mapper namespace="com.ivy.dao.UserDao">
    <!--    id写上对应的方法  resultType为返回值类型的类路径-->
    <select id="getUserList" resultType="com.ivy.pojo.User">select * from mybatis.user</select>
</mapper>

注册mapper到mybatis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">
<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/mybatis?useSSL=true"/>
                <property name="username" value="root"/>
                <property name="password" value="qwe123"/>
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <!--        这里写上你的mapper文件的路径-->
        <mapper resource="UserMapper.xml"/>
    </mappers>

</configuration>

编写测试类

package com.ivy.dao;

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

import java.util.List;


public class UserDaoTest {
    @Test
    public void test() {
        // 获取sqlSession对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        // 获取mapper对象
        UserDao mapper = sqlSession.getMapper(UserDao.class);


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

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

运行

User{id=1, name='zhang'}
User{id=2, name='wang'}
User{id=3, name='liu'}

最后整个项目结构

└─Mybatis1
    └─src
        ├─main
        │  ├─java
        │  │  └─com
        │  │      └─ivy
        │  │          ├─dao
        │  │          ├─pojo
        │  │          └─utils
        │  └─resources
        └─test
            └─java
                └─com
                    └─ivy
                        └─dao

基本的CRUD

实体类

package com.ivy.dao;

import com.ivy.pojo.User;

import java.util.List;

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

    User getUserById(int id);

    void createUser(User user);

    void updateUser(User user);

    void deleteUserById(int id);
}

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写上接口类的类路径-->
<mapper namespace="com.ivy.dao.UserDao">
    <!--    id写上对应的方法  resultType为返回值类型的类路径-->
    <select id="getUserList" resultType="com.ivy.pojo.User">select * from mybatis.user</select>

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

    <insert id="createUser" parameterType="com.ivy.pojo.User">
        insert into mybatis.user (`id`, `name`) values (#{id}, #{name})
    </insert>

    <update id="updateUser" parameterType="com.ivy.pojo.User">
        update mybatis.user set `name`=#{name} where id = #{id}
    </update>

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

测试类

package com.ivy.dao;

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

import java.util.List;


public class UserDaoTest {
    @Test
    public void getUserList() {
        // 获取sqlSession对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        // 获取mapper对象
        UserDao mapper = sqlSession.getMapper(UserDao.class);


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

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

    @Test
    public void getUserById() {
        // 获取sqlSession对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        // 获取mapper对象
        UserDao mapper = sqlSession.getMapper(UserDao.class);

        User user = mapper.getUserById(1);

        System.out.println(user);
        sqlSession.close();
    }

    @Test
    public void createUser() {
        // 获取sqlSession对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        // 获取mapper对象
        UserDao mapper = sqlSession.getMapper(UserDao.class);

        mapper.createUser(new User(4, "wangwu"));
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void updateUser() {
        // 获取sqlSession对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        // 获取mapper对象
        UserDao mapper = sqlSession.getMapper(UserDao.class);

        mapper.updateUser(new User(4, "xxxxx"));
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void deleteUserById() {
        // 获取sqlSession对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        // 获取mapper对象
        UserDao mapper = sqlSession.getMapper(UserDao.class);

        mapper.deleteUserById(4);
        sqlSession.commit();
        sqlSession.close();
    }
}

最后注意,对数据体进行增删改的操作的时候要提交事务。

posted @ 2020-09-05 13:10  Ivy丶  阅读(158)  评论(0)    收藏  举报