mybatis之简单Demo

1. 复习mybatis

首先导入依赖

<dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.11</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.2</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.2.0.RELEASE</version>
        </dependency>
        <!--Spring操作数据库需要一个spring-jdbc-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.2.0.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.9.4</version>
        </dependency>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>2.0.2</version>
        </dependency>
            <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.16.10</version>
        </dependency>
    </dependencies>
    <!--maven静态资源过滤：在使用Maven构建项目的时候，会默认过滤掉静态资源，所以需要手动来配置-->
    <build>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.properties</include>
                    <include>**/*.xml</include>
                </includes>
                <filtering>true</filtering>
            </resource>
        </resources>
    </build>

1. 编写实体类

   package com.zzy.pojo;
   import lombok.Data;
   /**
    * @author ZhaoZhiyue
    * @DATE 2020/11/8 - 0:23
    */
   @Data
   public class User {
       private int id;
       private String name;
       private String pwd;
   }  
   

2. 编写核心配置文件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>
       <typeAliases>
           <package name="com.zzy.pojo"/>
       </typeAliases>
   
       <environments default="development">
           <environment id="development">
               <transactionManager type="JDBC"></transactionManager>
               <dataSource type="POOLED">
                   <property name="driver" value="com.mysql.jdbc.Driver"/>
                   <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=false"/>
                   <property name="username" value="root"/>
                   <property name="password" value="123456"/>
               </dataSource>
           </environment>
       </environments>
   
       <mappers>
           <mapper class="com.zzy.mapper.UserMapper"/>
       </mappers>
   </configuration>
   

3. 编写接口

   package com.zzy.mapper;
   import com.zzy.pojo.User;
   import java.util.List;
   
   /**
    * @author ZhaoZhiyue
    * @DATE 2020/11/8 - 0:29
    */
   public interface UserMapper {
       public List<User> selectUser();
   }
   
   

4. 编写Mapper.xml

   <?xml version="1.0" encoding="UTF-8" ?>
   <!DOCTYPE mapper
           PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
           "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
   
   <mapper namespace="com.zzy.mapper.UserMapper">
       <select id="selectUser" resultType="user">
       select * from mybatis.user;
       </select>
   </mapper>
   

5. 测试

• 项目结构如下
  

• 数据库准备

 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,'张三','1234'),(2,'李四','1234');

• 测试

  import com.zzy.mapper.UserMapper;
  import com.zzy.pojo.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.Test;
  import java.io.IOException;
  import java.io.InputStream;
  import java.util.List;
  
  /**
   * @author ZhaoZhiyue
   * @DATE 2020/11/8 - 0:33
   */
  public class Mytest {
      @Test
      public void test() throws IOException {
          String resources = "mybatis-config.xml";
          InputStream in = Resources.getResourceAsStream(resources);
          SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(in);
          SqlSession sqlSession = sessionFactory.openSession(true);
          UserMapper mapper = sqlSession.getMapper(UserMapper.class);
          List<User> users = mapper.selectUser();
          for (User user : users) {
              System.out.println(user);
          }
  
      }
  }
  

• 运行结果