01-MyBatis-MyBatis起步

1、第一个MyBatis程序

步骤：

1. 导入jar包

   <dependency>
      <groupId>org.mybatis</groupId>
      <artifactId>mybatis</artifactId>
      <version>3.5.2</version>
   </dependency>
   <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.47</version>
   </dependency>
   

2. 编写(数据库)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&amp;useUnicode=true&amp;characterEncoding=utf8"/>
                  <property name="username" value="root"/>
                  <property name="password" value="123456"/>
              </dataSource>
          </environment>
      </environments>
      <mappers>
          <mapper resource="com/nuc/dao/userMapper.xml"/>
      </mappers>
   </configuration>
   

3. 编写MyBatis工具类

   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 {
              String resource = "mybatis-config.xml";
              InputStream inputStream = Resources.getResourceAsStream(resource);
              sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
         } catch (IOException e) {
              e.printStackTrace();
         }
     }
   
      //获取SqlSession连接
      public static SqlSession getSession(){
          return sqlSessionFactory.openSession();
     }
   
   }
   

4. 创建实体类

   public class User {
      
      private int id;  //id
      private String name;   //姓名
      private String pwd;   //密码
   
   }
   

5. 编写Mapper接口

   import com.nuc.pojo.User;
   import java.util.List;
   
   public interface UserMapper {
      List<User> selectUser();
   }
   

6. 编写Mapper.xml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">
   <mapper namespace="com.nuc.dao.UserMapper">
    <select id="selectUser" resultType="com.nuc.pojo.User">
     select * from user
    </select>
   </mapper>
   

7. 测试（JUnit单元测试）

   public class MyTest {
      @Test
      public void selectUser() {
          SqlSession session = MybatisUtils.getSession();
          UserMapper mapper = session.getMapper(UserMapper.class);
          List<User> users = mapper.selectUser();
   
          for (User user: users){
              System.out.println(user);
         }
          session.close();
     }
   }
   

8. Maven静态资源过滤问题

   <resources>
      <resource>
          <directory>src/main/java</directory>
          <includes>
              <include>**/*.properties</include>
              <include>**/*.xml</include>
          </includes>
          <filtering>false</filtering>
      </resource>
      <resource>
          <directory>src/main/resources</directory>
          <includes>
              <include>**/*.properties</include>
              <include>**/*.xml</include>
          </includes>
          <filtering>false</filtering>
      </resource>
   </resources>