SpringBoot+Mybatis注解方式实现关联查询

User实体类

package per.czt.pojo;

import org.springframework.boot.autoconfigure.domain.EntityScan;



public class User {
	private Integer user_id;

	private Town town;

	private String user_account;
	private String user_password;
	public Integer getUser_id() {
		return user_id;
	}

	public void setUser_id(Integer user_id) {
		this.user_id = user_id;
	}

	
	public Town getTown() {
		return town;
	}

	public void setTown(Town town) {
		this.town = town;
	}



	public String getUser_account() {
		return user_account;
	}

	public void setUser_account(String user_account) {
		this.user_account = user_account;
	}

	public String getUser_password() {
		return user_password;
	}

	public void setUser_password(String user_password) {
		this.user_password = user_password;
	}

	
	public User() {
		super();
		// TODO Auto-generated constructor stub
	}
	
	
	

}

Town实体类

package per.czt.pojo;

public class Town {
	private Integer town_id;
	private String town_name;
	/*private Integer city_id;*/
	private City city;
	public Integer getTown_id() {
		return town_id;
	}
	public void setTown_id(Integer town_id) {
		this.town_id = town_id;
	}
	public String getTown_name() {
		return town_name;
	}
	public void setTown_name(String town_name) {
		this.town_name = town_name;
	}
	
	public City getCity() {
		return city;
	}
	public void setCity(City city) {
		this.city = city;
	}
	public Town() {
		super();
		// TODO Auto-generated constructor stub
	}
	public Town(Integer town_id, String town_name, City city) {
		super();
		this.town_id = town_id;
		this.town_name = town_name;
		this.city = city;
	}
	
}

City实体类

package per.czt.pojo;

public class City {
	private Integer city_id;
	private String city_name;
	/*private Integer country_id;*/
	private Country country;
	public City() {
		super();
		// TODO Auto-generated constructor stub
	}
	public Integer getCity_id() {
		return city_id;
	}
	public void setCity_id(Integer city_id) {
		this.city_id = city_id;
	}
	public String getCity_name() {
		return city_name;
	}
	public void setCity_name(String city_name) {
		this.city_name = city_name;
	}
	public Country getCountry() {
		return country;
	}
	public void setCountry(Country country) {
		this.country = country;
	}
	public City(Integer city_id, String city_name, Country country) {
		super();
		this.city_id = city_id;
		this.city_name = city_name;
		this.country = country;
	}
	
}

UserMapper.xml文件

UserMapper接口

package per.czt.mapper;

import java.util.List;

import org.apache.ibatis.annotations.One;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;

import per.czt.pojo.User;

public interface UserMapper {
	@Select("select * from user")
	@Results({@Result(property="town",column="town_id",one=@One(select="per.czt.mapper.TownMapper.findTownById"))})
	public List searchAllUsers();

}

TownMapper.xml文件

TownMapper接口

package per.czt.mapper;

import org.apache.ibatis.annotations.One;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;

import per.czt.pojo.Town;

public interface TownMapper {
	@Select("select * from town where town_id=#{town_id}")
	@Results({@Result(column="city_id",property="city",one=@One(select="per.czt.mapper.CityMapper.findCityById"))})
	public Town findTownById(Integer town_id);

}

CityMapper.xml文件

CityMapper接口

package per.czt.mapper;

import org.apache.ibatis.annotations.One;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;

import per.czt.pojo.City;

public interface CityMapper {
	@Select("select * from city where city_id=#{city_id}")
	public City findCityById(Integer city_id);
}

UserService接口

package per.czt.service;

import java.util.List;

import per.czt.pojo.User;

public interface UserService {
	public List searchAllUsers();

}

UserServiceImpl 实现类

package per.czt.service.impl;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import per.czt.mapper.UserMapper;
import per.czt.pojo.User;
import per.czt.service.UserService;
@Service
@Transactional
public class UserServiceImpl implements UserService {
	@Autowired
	private UserMapper userMapper;

	@Override
	public List searchAllUsers() {
		return userMapper.searchAllUsers();
	}

}

UserController

package per.czt.controller;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;

import per.czt.pojo.User;
import per.czt.service.UserService;

@Controller
@RequestMapping("/user")
public class UserController {
	@Autowired
	private UserService userService;
	
	
	@RequestMapping("/{page}")
	public String showPage(@PathVariable String page) {
		return page;
	}
	@RequestMapping("/showAll")
	public String showAllUsers(Model model) {
		
		
		List userList=userService.searchAllUsers();
		model.addAttribute("userList",userList);
		System.out.println("userList:"+userList);
		for(User u:userList) {
			System.out.println("user_id:"+u.getUser_id());
			System.out.println("user_account:"+u.getUser_account());
			System.out.println("user_password:"+u.getUser_password());
			System.out.println("user_profession:"+u.getProfession());
			System.out.println("user_town:"+u.getTown());
			System.out.println("user_town_id:"+u.getTown().getTown_id());
			System.out.println("user_town_name:"+u.getTown().getTown_name());
			System.out.println("user_city:"+u.getTown().getCity());
			System.out.println("user_city_id:"+u.getTown().getCity().getCity_id());
			System.out.println("user_city_name:"+u.getTown().getCity().getCity_name())；
			System.out.println();
		}
		return "userlist";
	}
	
	

}

view层:userList.html，这里使用了thymeleaf模板

	

		

			
用户ID
			
用户账号
			
用户密码
			
乡镇名称
			
城市名称
		
		

			

			

			

			

			

		
	
	

SpringBoot启动类

package per.czt;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

/**
 * Hello world!
 *
 */
@SpringBootApplication
@MapperScan("per.czt.mapper")
public class App 
{
    public static void main( String[] args )
    {
        SpringApplication.run(App.class, args);
    }
}

运行结果