Mybatis注解开发 注解开发只需要写mapper接口即可，无需再书写对应的xxMapper.xml映射文件 对于单表操作还是比较方便的，但对多表操作就维护起来就比较麻烦了 数据库准备 添加依赖 !--
Mybatis注解开发
注解开发只需要写mapper接口即可，无需再书写对应的xxMapper.xml映射文件
对于单表操作还是比较方便的，但对多表操作就维护起来就比较麻烦了
数据库准备
添加依赖
<!--lombok-->
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.12</version>
<scope>provided</scope>
</dependency>
<!-- mybatis -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.6</version>
</dependency>
<!-- mysql驱动 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.16</version>
</dependency>
<!-- 测试用例 -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
<!-- 日志 -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>1.6.4</version>
</dependency>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>
<!-- 引入外部的配置文件 -->
<properties resource="jdbc.properties"/>
<!-- 开启驼峰匹配 -->
<settings>
<setting name="mapUnderscoreToCamelCase" value="true"/>
</settings>
<!-- 连接数据库相关的配置 后面不用写，spring代替-->
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="${driverClass}"/>
<property name="url" value="${url}"/>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
</dataSource>
</environment>
</environments>
<mappers>
<package name="cn.yanqi.mapper"/>
</mappers>
</configuration>jdbc.properties
driverClass=com.mysql.jdbc.Driver
url=jdbc:mysql:///mybatis
jdbc.username=root
jdbc.password=root
单表操作
实体类
@Data
public class User {
private Long id;
// 用户名
private String userName;
// 密码
private String password;
// 姓名
private String name;
// 年龄
private Integer age;
// 性别，1男性，2女性
private Integer sex;
// 出生日期
private Date birthday;
// 创建时间
private Date created;
// 更新时间
private Date updated;
}Mapper接口
/**
* @Auther: yanqi
* @Date:
* @Dese:
*/
public interface UserMapper {
@Select("select * from tb_user where id = #{id}")
User findById(int id);
@Select("select * from tb_user")
List<User> selectAll();
@Insert("INSERT INTO tb_user(id, user_name, password, name, age, sex, birthday, created, updated) VALUES (null,#{userName},#{password},#{name},#{age},#{sex},#{birthday},#{created},#{updated})")
void adduser(User user);
@Delete("delete from tb_user where id = #{id}")
void delete(int id);
@Update("update tb_user set user_name =#{userName} , updated = #{updated} where id =#{id}")
void updateuser(User user);
}测试
/**
* @Auther: yanqi
* @Date:
* @Dese:
*/
public class UserMapperTest {
private UserMapper userMapper;
private SqlSession sqlSession ;
private SqlSessionFactory sqlSessionFactory ;
@Before
public void setUp() throws Exception {
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
sqlSession = sqlSessionFactory.openSession();
userMapper = sqlSession.getMapper(UserMapper.class);
}
/**
* 查询单个
*/
@Test
public void select() {
User user = this.userMapper.findById(1);
System.out.println(user);
}
/**
* 查询所有
*/
@Test
public void selectAll() {
List<User> users = this.userMapper.selectAll();
for(User user : users){
System.out.println(user);
}
}
/**
* 添加
*/
@Test
public void adduser() {
User user = new User();
user.setUserName("小江江");
user.setPassword("123");
user.setName("一燕");
user.setAge(27);
user.setSex(2);
user.setBirthday(new Date());
user.setCreated(new Date());
user.setUpdated(new Date());
this.userMapper.adduser(user);
this.sqlSession.commit();
}
/**
* 删除
*/
@Test
public void delete() {
this.userMapper.delete(114);
this.sqlSession.commit();
}
/**
* 修改
*/
@Test
public void updateuser() {
User user = new User();
user.setId(118L);
user.setUserName("哈哈2");
user.setUpdated(new Date());
this.userMapper.updateuser(user);
this.sqlSession.commit();
}
}一对一
实体类
/**
* 订单表
*/
@Data
public class Order {
private Integer id;
private Long userId;
private String orderNumber;
private User user;
}Mapper接口
/**
* @Auther: yanqi
* @Dese: OrderMapper接口 实现一对一
*/
public interface OrderMapper {
/**
* 查询订单，并且查询出下单人的信息
* @param
* @return
*/
@Select("select * from tb_order where order_number = #{orderNum}")
@Results({
/*映射user
column: order表中user_id外键，传递给UserMapper.findById的id
property: order实体类中的user字段
*/
@Result(
column = "id",
property ="user",
javaType = User.class,
one = @One(select = "cn.yanqi.mapper.UserMapper.findById"))
})
List<Order> oneToOne(String orderNum);
}public interface UserMapper {
@Select("select * from tb_user where id = #{id}")
User findById(int id);
}测试
/**
* @Auther: yanqi
* @Date:
* @Dese:
*/
public class UserMapperTest {
private UserMapper userMapper;
private OrderMapper orderMapper;
private SqlSession sqlSession ;
private SqlSessionFactory sqlSessionFactory ;
@Before
public void setUp() throws Exception {
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
sqlSession = sqlSessionFactory.openSession();
userMapper = sqlSession.getMapper(UserMapper.class);
orderMapper = sqlSession.getMapper(OrderMapper.class);
}
/**
* 测试一对一
*/
@Test
public void oneToOne(){
List<Order> orders = this.orderMapper.oneToOne("20200921002");
for(Order order : orders){
System.out.println(order);
}
}一对多
实体类
/**
* 订单表
*
*/
@Data
public class Order {
private Integer id;
private Long userId;
private String orderNumber;
private User user;
private List<Orderdetail> orderdetails;
}@Data
public class Orderdetail {
private Integer id;
private Double totalPrice;
private Integer status;
}Mapper接口
/**
* @Auther: yanqi
* @Date:
* @Dese:
*/
public interface OrderMapper {
/**
* 查询订单，查询出下单人信息并且查询出订单详情。
*/
@Select("select * from tb_order where order_number = #{orderNum}")
@Results({
/*映射user*/
@Result(column = "id",
property ="user",
javaType = User.class,
one = @One(select = "cn.yanqi.mapper.UserMapper.findById")),
/*映射orderdetails*/
@Result(column = "id",
property = "orderdetails",
javaType =List.class,
many = @Many(select = "cn.yanqi.mapper.OrderDetailMapper.findById"))
})
List<Order> oneToMany(String orderNum);
}/**
* @Auther: yanqi
*/
public interface OrderDetailMapper {
/**
* 根据id查询订单详情
* @param id
*/
@Select("select * from tb_orderdetail where id = #{id}")
Orderdetail findById(int id);
}测试
/**
* @Auther: yanqi
* @Date:
* @Dese:
*/
public class UserMapperTest {
private UserMapper userMapper;
private OrderMapper orderMapper;
private SqlSession sqlSession ;
private SqlSessionFactory sqlSessionFactory ;
@Before
public void setUp() throws Exception {
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
sqlSession = sqlSessionFactory.openSession();
userMapper = sqlSession.getMapper(UserMapper.class);
orderMapper = sqlSession.getMapper(OrderMapper.class);
}
/**
* 测试一对多
*/
@Test
public void oneToMany(){
List<Order> orders = this.orderMapper.oneToMany("20200921002");
for(Order order : orders){
System.out.println(order);
}多对多
实体类
/**
* 订单详情
*/
@Data
public class Orderdetail {
private Integer id;
private Double totalPrice;
private Integer status;
//商品信息
private Item item;
}/**
* 商品表
*/
@Data
public class Item {
private Integer id;
private String itemName;
private Float itemPrice;
private String itemDetail;
}Mapper接口
public interface OrderMapper {
/**
* 查询订单，查询出下单人信息并且查询出订单详情中的商品数据。
*/
@Select("select * from tb_order where order_number = #{orderNum}")
@Results({
/*映射user*/
@Result(column = "id",
property ="user",
javaType = User.class,
one = @One(select = "cn.yanqi.mapper.UserMapper.findById")),
/*映射orderdetails*/
@Result(column = "id",
property = "orderdetails",
javaType =List.class,
//查询Item商品
many = @Many(select = "cn.yanqi.mapper.ItemMapper.findById"))
})
List<Order> manyToMany(String orderNum);
}public interface ItemMapper {
@Select("select * from tb_item where id = #{id}")
List<Item> findById(Integer id);
}测试
/**
* 测试多对多
*/
@Test
public void manyToMany() {
List<Order> orders = this.orderMapper.manyToMany("20200921002");
for (Order order : orders) {
System.out.println(order);
}
}