public class User {
private int id;
private String name;
private String dept;
private String phone;
private String website;
// 省略 get set 方法
}
创建配置
创建映射
测试
public class Main {
private static SqlSessionFactory sqlSessionFactory;
private static SqlSession sqlSession;
private static Reader reader;
static {
try {
reader = Resources.getResourceAsReader("config/mybatis-config.xml");
} catch (IOException e) {
e.printStackTrace();
}
sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
sqlSession = sqlSessionFactory.openSession();
}
@Test
public void test {
User user = sqlSession.selectOne("getUserById", 1);
System.out.println(user);
}
}
CURD
创建实体（同上）
创建 IUser
public interface IUser {
public List getUserList();
public void insertUser(User user);
public void updateUser(User user);
public void deleteUser(int userId);
public User getUser(int id);
}
创建配置（同上）
创建映射
No.2 关联查询
一对多
创建实体
User
public class User implements Serializable {
private int id;
private String username;
private String mobile;
private List posts;
// 省略 get 和 set
// 重写 toString
}
Post
public class Post implements Serializable {
private int id;
private User user;
private String title;
private String content;
// 省略 get 和 set
// 重写 toString
}
创建配置（同上）
创建映射
多对一
创建实体（同上）
创建配置（同上）
创建映射
多对多
创建实体
OrderItem
public class OrderItem {
private int id;
private int number;
private Order order;
private Product product;
// 省略 get 和 set
}
Order
public class Order {
private int id;
private String code;
List orderItems;
// 省略 get 和 set
}
创建映射
OrderItem.xml
insert into order_item_
values(null,#{order.id},#{product.id},#{number})
delete from order_item_
where oid = #{order.id} and pid = #{product.id}
创建接口，使用 @Insert()、@Update()、@Select()、@Delete() 替代 xml 的语句
在配置文件中增加
一对多
@Results 通过 @Result 和 @Many 中调用多端方法相结合，来获取一对多关系
CategoryMapper
public interface CategoryMapper {
@Select("select * from category_")
@Results({
@Result(property = "id", column = "id"),
@Result(property = "products",
javaType = List.class,
column = "id",
many = @Many(select = "com.kernel.pojo.ProductMapper.listByCategory"))
})
public List list();
}
ProductMapper
public interface ProductMapper {
@Select(" select * from product_ where cid = #{cid}")
public List listByCategory(int cid);
}
多对一
ProductMapper
@Select("select * from product_")
@Results(
@Result(property = "category", column = "id", one = @One(select = "com.kernel.pojo.CategoryMapper.get"))
)
public List list();
CategoryMapper
@Select("select * from category_ where id = #{id}")
public Category get(int id);
多对多
ProductMapper
public interface ProductMapper {
@Select("select * from product_ where id = #{id}")
public Product get(int id);
}
OrderItemMapper
public interface OrderItemMapper {
@Select("select * from order_item_ where oid = #{oid}")
@Results({
@Result(property = "product", column = "pid", one = @One(select = "com.kernel.pojo.ProductMapper.get"))
})
public List listByOrder(int oid);
}
OrderMapper
public interface OrderMapper {
@Select("select * from order_")
@Results({
@Result(property = "id", column = "id"),
@Result(property = "orderItems", javaType = List.class, column = "id",
many = @Many(select = "com.kernel.pojo.OrderItemMapper.listByOrder"))
})
public List list();
}
动态 SQL
关于 sql 类
private String selectPersonSql() {
return new SQL() {{
SELECT("P.ID, P.USERNAME, P.PASSWORD, P.FULL_NAME");
SELECT("P.LAST_NAME, P.CREATED_ON, P.UPDATED_ON");
FROM("PERSON P");
FROM("ACCOUNT A");
INNER_JOIN("DEPARTMENT D on D.ID = P.DEPARTMENT_ID");
INNER_JOIN("COMPANY C on D.COMPANY_ID = C.ID");
WHERE("P.ID = A.ID");
WHERE("P.FIRST_NAME like ?");
OR();
WHERE("P.LAST_NAME like ?");
GROUP_BY("P.ID");
HAVING("P.LAST_NAME like ?");
OR();
HAVING("P.FIRST_NAME like ?");
ORDER_BY("P.ID");
ORDER_BY("P.FULL_NAME");
}}.toString();
}
使用 SQL 类的方式构建
public class CategsoryDynaSqlProvider {
public String list() {
return new SQL()
.SELECT("*")
.FROM("category_")
.toString();
}
public String get() {
return new SQL()
.SELECT("*")
.FROM("category_")
.WHERE("id=#{id}")
.toString();
}
public String add(){
return new SQL()
.INSERT_INTO("category_")
.VALUES("name", "#{name}")
.toString();
}
public String update(){
return new SQL()
.UPDATE("category_")
.SET("name=#{name}")
.WHERE("id=#{id}")
.toString();
}
public String delete(){
return new SQL()
.DELETE_FROM("category_")
.WHERE("id=#{id}")
.toString();
}
}
注解
手写sql语句
@Insert(" insert into category_ ( name ) values (#{name}) ")
public int add(Category category);
使用sql类
@InsertProvider(type=CategoryDynaSqlProvider.class,method="add")
public int add(Category category);
