Mybatis框架搭建

Mybatis框架搭建

思路：

1. 搭建环境

2. 导入Mybatis

3. 编写代码

4. 测试

一.搭建环境

• 创建数据库

  /*
   Navicat Premium Data Transfer
  ​
   Source Server         : Mybatis
   Source Server Type    : MySQL
   Source Server Version : 50528
   Source Host           : localhost:3306
   Source Schema         : mybatis
  ​
   Target Server Type    : MySQL
   Target Server Version : 50528
   File Encoding         : 65001
  ​
   Date: 03/03/2022 13:11:06
  */
  ​
  SET NAMES utf8mb4;
  SET FOREIGN_KEY_CHECKS = 0;
  ​
  -- ----------------------------
  -- Table structure for employee
  -- ----------------------------
  DROP TABLE IF EXISTS `employee`;
  CREATE TABLE `employee`  (
    `id` int(10) NOT NULL AUTO_INCREMENT,
    `name` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
    `age` int(10) NOT NULL,
    `position` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
    PRIMARY KEY (`id`) USING BTREE
  ) ENGINE = InnoDB AUTO_INCREMENT = 4 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;
  ​
  -- ----------------------------
  -- Records of employee
  -- ----------------------------
  INSERT INTO `employee` VALUES (1, '张三', 20, '员工');
  INSERT INTO `employee` VALUES (2, '李四', 18, '员工');
  INSERT INTO `employee` VALUES (3, '王五', 35, '经理');
  ​
  SET FOREIGN_KEY_CHECKS = 1;
  ​

• 创建数据库连接信息配置文件db.properties

  db.driver = com.mysql.jdbc.Driver
  db.url = jdbc:mysql://localhost:3306/learn-test?useUnicode=true&characterEncoding=utf8 
  db.username = root
  db.password = root

• 新建项目,并且在pom.xml中添加项目依赖

  <?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>com.wfy</groupId>
      <artifactId>Worker</artifactId>
      <packaging>pom</packaging>
      <version>1.0-SNAPSHOT</version>
      <modules>
          <module>worker-01</module>
      </modules>
      <!--导入依赖-->
      <dependencies>
          <!--mybatis-->
          <dependency>
              <groupId>org.mybatis</groupId>
              <artifactId>mybatis</artifactId>
              <version>3.5.2</version>
          </dependency>
          <!--mysql驱动-->
          <dependency>
              <groupId>mysql</groupId>
              <artifactId>mysql-connector-java</artifactId>
              <version>8.0.11</version>
          </dependency>
          <!--junit-->
          <dependency>
              <groupId>junit</groupId>
              <artifactId>junit</artifactId>
              <version>4.12</version>
              <scope>test</scope>
          </dependency>
      </dependencies>
      <build>
          <resources>
              <resource>
                  <directory>src/main/java</directory>
                  <includes>
                      <include>**/*.xml</include>
                      <include>**/*.properties</include>
                  </includes>
              </resource>
  ​
              <resource>
                  <directory>src/main/resources</directory>
                  <includes>
                      <include>**/*.xml</include>
                      <include>**/*.properties</include>
                  </includes>
              </resource>
          </resources>
      </build>
  </project>
  ​

  二、创建模块

  • 创建Mybatis的核心配置文件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>
      <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="mapper/UserMapper"/>
      </mappers>
    </configuration>

• 编写Mybatis工具类

  package 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 MybatisUtil {
  ​
      private static SqlSessionFactory sqlSessionFactory;
  ​
      static {
          try {
              //使用Mybatis的第一步---->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();
          }
      }
      //既然有了 SqlSessionFactory，顾名思义，我们可以从中获得 SqlSession 的实例。
      // SqlSession 提供了在数据库执行 SQL 命令所需的所有方法。你可以通过 SqlSession 实例来直接执行已映射的 SQL 语句
      public static SqlSession getSqlSession()
      {
          return  sqlSessionFactory.openSession();
  ​
      }
  ​
  }
  ​

三.编写代码

• 实体类User 创建Pojo实体

  package pojo;
  ​
  //实体类
  public class User {
      private int id ;
      private  String name;
      private  int age;
      private  String position;
  ​
      public User() {
      }
  ​
      public User(int id, String name, int age, String position) {
          this.id = id;
          this.name = name;
          this.age = age;
          this.position = position;
      }
  ​
      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 int getAge() {
          return age;
      }
  ​
      public void setAge(int age) {
          this.age = age;
      }
  ​
      public String getPosition() {
          return position;
      }
  ​
      public void setPosition(String position) {
          this.position = position;
      }
  ​
      @Override
      public String toString() {
          return "User{" +
                  "id=" + id +
                  ", name='" + name + '\'' +
                  ", age=" + age +
                  ", position='" + position + '\'' +
                  '}';
      }
  }
  ​

• Dao接口

  <?xml version="1.0" encoding="UTF-8" ?>
  <!--namespace=绑定一个Mapper/Dao接口-->
  <!DOCTYPE mapper
          PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
          "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  <mapper namespace="dao.UserDao">
      <!--执行select查询语句-->
    <select id="getUserList" resultType="pojo.User">
        select * from mybatis.employee;
    </select>
  </mapper>

• 接口实现类

  package dao;
  ​
  import pojo.User;
  ​
  import java.util.List;
  ​
  //Dao接口
  public interface UserDao {
  ​
      List<User> getUserList();
  ​
  }
  ​

• 编写测试类

  package dao;
  ​
  import org.apache.ibatis.session.SqlSession;
  import org.junit.Test;
  import pojo.User;
  import utils.MybatisUtil;
  ​
  import java.util.List;
  ​
  public class UserDaoTest {
      @Test
      public void test ()
      {
          //第一步:获得SqlSession对象
         SqlSession sqlSession= MybatisUtil.getSqlSession();
         //第二步:执行SQL
          UserDao mapper=sqlSession.getMapper(UserDao.class);
         List<User> userList= mapper.getUserList();
          for (User user : userList) {
              System.out.println(user);
          }
  ​
          //关闭sqlSession
          sqlSession.close();
      }
  }
  ​