MyBatis 基于xml简单的CRUD

搭建项目框架 第一步：创建Maven项目

• 添加依赖

  
    junit
    junit
    4.12
    test


    org.projectlombok
    lombok
    1.18.10


    mysql
    mysql-connector-java
    8.0.11


    org.mybatis
    mybatis
    3.5.4

• 指定映射文件位置

    
        src/main/java
        
            **/*.xml
        
    

创建MySQL配置文件mysql.properties

driver=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://127.0.0.1/test?useSSL=false&serverTimezone=CST
username=root
password=root

第三步：创建MyBatis配置文件mybatis-cfg.xml

第四步：创建MyBatis工具类

public class MyBatisUtil {
	private static String CONFIG_FILE_LOCATION = "mybatis-cfg.xml";
	private static final ThreadLocal threadLocal = new 
													ThreadLocal();
    private static SqlSessionFactory sessionFactory;
    
    static {
    		try {
			Reader reader=Resources.getResourceAsReader(CONFIG_FILE_LOCATION);
			SqlSessionFactoryBuilder builder=new SqlSessionFactoryBuilder();
			sessionFactory=builder.build(reader);
		} catch (Exception e) {
			e.printStackTrace();
		}
    }
    
    public static SqlSession getSession() {
    		SqlSession  session = threadLocal.get();
		if (session == null) {
			session = (sessionFactory!=null) ? sessionFactory.openSession() : null;
			threadLocal.set(session);
		}
        return session;
    }
    public static void closeSession()  {
    	   SqlSession session = threadLocal.get();
        if (session != null) {
            session.close();
  		   threadLocal.set(null);
        }
    }
}

具体代码 第一步：创建实体类

@Getter
@Setter
@Builder
@NoArgsConstructor
@AllArgsConstructor
@ToString(callSuper = true)
public class Dept {
    /**
     * 部门编号
     */
    private Byte deptno;

    /**
     * 部门名称
     */
    private String dname;

    /**
     * 部门地址
     */
    private String loc;
}

第二步：创建DeptDao.java

public interface DeptDao {
    int deleteByPrimaryKey(Byte deptno);

    int insert(Dept record);

    int insertSelective(Dept record);

    Dept selectByPrimaryKey(Byte deptno);

    int updateByPrimaryKeySelective(Dept record);

    int updateByPrimaryKey(Dept record);
}

第三步：创建DeptDao.xml

    
        
        
        
    
    
    
   		deptno, dname, loc
    
    
    
        select
        
        from tb_dept
        where deptno = #{deptno,jdbcType=TINYINT}
    
    
    
	    delete from tb_dept
	    where deptno = #{deptno,jdbcType=TINYINT}
  	
  
    
	    insert into tb_dept (deptno, dname, loc )
	    values (#{deptno,jdbcType=TINYINT}, #{dname,jdbcType=VARCHAR}, #{loc,jdbcType=VARCHAR} )
	  
  
    
        insert into tb_dept
        
            
                deptno,
            
            
                dname,
            
            
                loc,
            
        
        
            
                #{deptno,jdbcType=TINYINT},
            
            
                #{dname,jdbcType=VARCHAR},
            
            
                #{loc,jdbcType=VARCHAR},
            
        
    
    
    
        update tb_dept
        
            
                dname = #{dname,jdbcType=VARCHAR},
            
            
                loc = #{loc,jdbcType=VARCHAR},
            
        
        where deptno = #{deptno,jdbcType=TINYINT}
    
    
    
	    update tb_dept
	    set dname = #{dname,jdbcType=VARCHAR},
	      loc = #{loc,jdbcType=VARCHAR}
	    where deptno = #{deptno,jdbcType=TINYINT}
	  
  

第四步：测试代码

public class DeptMapperTest {

    private SqlSession session;
    private  DeptDao mapper;
    @Before
    public void before(){
          session = MyBatisUtil.getSession();
          mapper = session.getMapper(DeptDao.class);
    }
    @After
    public void after(){
        session.commit();
    }
    @Test
    public void deleteByPrimaryKey() {
        int res = mapper.deleteByPrimaryKey((byte) 46);
        System.out.println(res);
    }

    @Test
    public void insert() {
        Dept dept = new Dept((byte)1,"aa","aaaaaaaaaaa");
        int res = mapper.insert(dept);
        System.out.println(res);
    }

    @Test
    public void insertSelective() {
        Dept dept = new Dept();
        dept.setDname("abcd");
        int res = mapper.insertSelective(dept);
        System.out.println(res);
    }

    @Test
    public void selectByPrimaryKey() {
        Dept dept = mapper.selectByPrimaryKey((byte) 10);
        System.out.println(dept);
    }

    @Test
    public void updateByPrimaryKeySelective() {
        Dept dept = new Dept();
        dept.setDeptno((byte)40);
        dept.setDname("abc");
        int res = mapper.updateByPrimaryKeySelective(dept);
        System.out.println(res);
    }

    @Test
    public void updateByPrimaryKey() {
//        Dept dept = new Dept();
//        dept.setDeptno((byte)47);
//        dept.setDname("asdf");
//        int res = mapper.updateByPrimaryKey(dept);
        System.out.println(3/0);
    }
}