第一个mybatis程序

第一个mybatis程序

搭建环境->导入mybatis->代码->测试

1.搭建环境

搭建数据库

CREATE DATABASE `mybatis`;
USE `mybatis`;

CREATE TABLE `user`(
  `id` INT(20) NOT NULL PRIMARY KEY,
  `name` VARCHAR(30) DEFAULT NULL,
  `pwd` VARCHAR(30) DEFAULT NULL
  )ENGINE=INNODB DEFAULT CHARSET=utf8;
  
  
INSERT INTO `user`(`id`,`name`,`pwd`) VALUES
(1,'wo','123456'),
(2,'ta','123456'),
(3,'zhangsan','123456')

新建项目

​ 1.新建一个普通的maven项目

​ 2.删除src目录

​ 3.导入依赖

<dependencies>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.18</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.3</version>
        </dependency>        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
        <version>4.12</version>
    </dependency>
    </dependencies>

2.创建一个新的模块

• 编写mybatis的核心配置文件

  <?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">
  <!--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?useUnicode=ture&amp;characterEncoding=UTF-8"/>
                  <property name="username" value="root"/>
                  <property name="password" value="123456"/>
              </dataSource>
          </environment>
      </environments>
  </configuration>				
  

• 编写mybatis工具类

  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();
          }
      }
  //    sqlSession包含了面向数据库执行sql命令所需的所有方法
      public static SqlSession getSqlSession(){
          return sqlSessionFactory.openSession();
      }
  }
  

3.编写代码

• 实体类

  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 + '\'' +
                  '}';
      }
  }
  

• Dao接口

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

• 接口实现类

  <?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绑定对应的Dao/Mapper接口-->
  <mapper namespace="cn.pinked.dao.UserDao">
      <select id="getUserList" resultType="cn.pinked.pojo.User">
          select * from mybatis.user
      </select>
  </mapper>
  

4.测试

• junit

  @Test
      public void Test(){
  //        获得SqlSession对象
          SqlSession sqlSession = MybatisUtils.getSqlSession();
  //        方式:getMapper
          UserDao userDao = sqlSession.getMapper(UserDao.class);
          List<User> userList = userDao.getUserList();
  
          for (User user : userList) {
              System.out.println(user);
          }
  
          sqlSession.close();//关闭SqlSession
      }