实现的方法，有两种不同的风格，
一种是直接在接口里用注解实现，
另一种还是稳重的写xml，用resultmap来搞定。
经过几天的复习，
这个知识点差不多了。
参考URL：
http://blog.csdn.net/KingBoyWorld/article/details/78966789
建表语句：
CREATE TABLE IF NOT EXISTS `user` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`nick_name` varchar(50) DEFAULT NULL,
`address_id` int(11) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
CREATE TABLE IF NOT EXISTS `address` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`province` varchar(50) DEFAULT NULL,
`city` varchar(50) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
CREATE TABLE IF NOT EXISTS `car` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`color` varchar(50) DEFAULT NULL,
`name` varchar(50) DEFAULT NULL,
`user_id` int(11) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO
`user`
VALUES
('1', 'baby', '1'),
('2', 'kingboy', '2'),
('3', 'boy', '3'),
('4', 'kingbaby', '4');
INSERT INTO
`address`
VALUES
('1', '北京', '北京'),
('2', '天津', '天津'),
('3', '安徽', '宿州'),
('4', '广东', '广州');
INSERT INTO
`car`
VALUES
('1', 'green', '路虎', '1'),
('2', 'white', '奔驰', '2'),
('3', 'blue', '玛莎拉蒂', '4'),
('4', 'yellow', '兰博基尼', '4');几个pojo，注意的是没有用外键关联，只是用了外键来对应，哪个表需要取外面的关联的，就要在POJO里建立对应的属性。
package opsstock.paic.com.cn.entity;
public class Address {
private Long id;
private String province;
private String city;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getProvince() {
return province;
}
public void setProvince(String province) {
this.province = province;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
@Override
public String toString() {
return "Address [id=" + id + ", province=" + province + ", city=" + city + "]";
}
}
package opsstock.paic.com.cn.entity;
import java.util.List;
public class User {
private Long id;
private String name;
private Address address;
private Long addressId;
private List<Car> cars;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Address getAddress() {
return address;
}
public void setAddress(Address address) {
this.address = address;
}
public Long getAddressId() {
return addressId;
}
public void setAddressId(Long addressId) {
this.addressId = addressId;
}
public List<Car> getCars() {
return cars;
}
public void setCars(List<Car> cars) {
this.cars = cars;
}
@Override
public String toString() {
return "User [id=" + id + ", name=" + name + ", addressId=" + addressId + "]";
}
}
package opsstock.paic.com.cn.entity;
public class Car {
private Long id;
private String name;
private String color;
private Long userId;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getColor() {
return color;
}
public void setColor(String color) {
this.color = color;
}
public Long getUserId() {
return userId;
}
public void setUserId(Long userId) {
this.userId = userId;
}
@Override
public String toString() {
return "Car [id=" + id + ", name=" + name + ", color=" + color + ", userId=" + userId + "]";
}
}
相关mapper的写法，我总觉得，应该可以简化那个路径吧。
package opsstock.paic.com.cn.mapper;
import org.apache.ibatis.annotations.Select;
import opsstock.paic.com.cn.entity.Address;
public interface AddressRepository {
@Select("SELECT * FROM `address` WHERE id = #{id}")
Address findAddressById(Long id);
}
package opsstock.paic.com.cn.mapper;
import java.util.List;
import org.apache.ibatis.annotations.Select;
import opsstock.paic.com.cn.entity.Car;
public interface CarRepository {
@Select("SELECT * FROM `car` WHERE user_id = #{userId}")
List<Car> findCarByUserId(Long userId);
}
注意@One和@Many的注解哟
package opsstock.paic.com.cn.mapper;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.One;
import org.apache.ibatis.annotations.Many;
import opsstock.paic.com.cn.entity.User;
public interface UserRepository {
@Select("SELECT * FROM `user` WHERE id=#{id}")
@Results({
@Result(property="address", column="address_id",
one = @One(select = "opsstock.paic.com.cn.mapper.AddressRepository.findAddressById"))
})
User findUserWithAddress(Long id);
@Select("SELECT * FROM `user` WHERE id = #{id}")
@Results({
@Result(property="cars", column="id",
many = @Many(select="opsstock.paic.com.cn.mapper.CarRepository.findCarByUserId"))
})
User getUserWithCar(Long id);
}
省掉service，直接测试：
package opsstock.paic.com.cn.controller;
import javax.annotation.Resource;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import opsstock.paic.com.cn.entity.User;
import opsstock.paic.com.cn.mapper.UserRepository;
@RestController
@RequestMapping(value="/user")
public class UserController {
@Resource
UserRepository userRepository;
@GetMapping(value="/id/{id}/include/address")
public String findUserWithAddress(@PathVariable Long id) {
User userWithAddress = userRepository.findUserWithAddress(id);
return userWithAddress.getAddress().toString();
}
@GetMapping(value = "/id/{id}/include/car")
public String findUserWithCar(@PathVariable Long id) {
User user = userRepository.getUserWithCar(id);
return user.getCars().toString();
}
}
则输入网址：
http://localhost:8080/user/id/4/include/car
返回结果：
[Car [id=3, name=ÂêɯÀµÙ, color=blue, userId=4], Car [id=4, name=À¼²©»ùÄá, color=yellow, userId=4]]
(没有理会乱码之事)
