Java Maven專案:spring boot + Mybatis連線MySQL,通用mapper的增刪改查,對映實現多表查詢
1. MySQL自帶庫test新增表user、role
角色表role 使用者表user
2. 新增依賴,配置屬性
相關依賴:百度即可,此處略
application.properties
spring.application.name=clean-exe server.port=8845 server.main.class=com.cdqd.app.main.Application eureka.client.serviceUrl.defaultZone=http://192.168.3.231:8765/eureka/,http://192.168.3.232:8765/eureka/ logging.config=classpath:logback.xml #測試資料庫 spring.datasource.url=jdbc:mysql://127.0.0.1:3306/test spring.datasource.username=root spring.datasource.password=password spring.datasource.driver-class-name=com.mysql.jdbc.Driver #mybatis&&通用Mapper mybatis.type-aliases-package=com.cdqd.app.bean mybatis.mapper-locations=classpath:mapper/*.xml mapper.mappers=com.cdqd.app.common.TkMapper mapper.identity=MYSQL mapper.not-empty=false
server.port為訪問埠,訪問方式為:localhost:[server.port]/[控制器名] spring.datasource.url後需要新增兩個屬性,不然會發出警告
3.新建實體類User,Role,UserRole(省略getter、setter)
user.java
import java.util.Date; import javax.persistence.Column; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.Table; @Table(name = "user") public class User { //自增ID屬性 @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Integer id; //名稱 @Column(name = "name") private String name; //年齡 @Column(name = "age") private Integer age; //身份編號 @Column(name = "card_no") private Integer cardNo; //生日 @Column(name = "birthday") private Date birthday; //角色id @Column(name = "r_id") private int rId; }
UserRole.java
import com.cdqd.app.bean.User;
public class UserRole extends User {
private int roleId;
private String roleName;
private int atk;
private int armor;
private int penetrate;
}
Role.java省略,修改後貌似不需要此實體類
4. 通用mapper實現user表的增刪改查
(1). 寫一個自己的介面繼承通用mapper,此介面不能被掃描到
import tk.mybatis.mapper.common.Mapper; import tk.mybatis.mapper.common.MySqlMapper; public interface TkMapper<T> extends Mapper<T>, MySqlMapper<T> { }
(2). 新增UserMapper繼承之前寫的mapper,用於自己使用
import com.cdqd.app.entity.UserRole;
import com.cdqd.app.bean.User;
import com.cdqd.app.common.TkMapper;
import java.util.List;
public interface UserMapper extends TkMapper<User> {
List<UserRole> getUserRoleByUserId(int id);
}
注:此mapper需要被掃描到 getUserRoleByUserId用於對映多表查詢,使用對映檔案操作流程為: controller呼叫service,service呼叫mapper
(3). 編寫controller
SqlTestController.java
import com.cdqd.app.bean.User;
import com.cdqd.app.entity.UserRole;
import com.cdqd.app.mapper.UserMapper;
import com.cdqd.app.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import javax.annotation.Resource;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.List;
@RestController
public class SqlTestController {
//自動注入,一般放在頂部
@Autowired
UserMapper userMapper;
@Autowired
private UserService userService;
//測試controller用
@PostMapping("/hello")
public String hello(String yourName) {
return "Hello," + yourName;
}
//根據cardNo查詢一條資料
//只能用於主鍵查詢,不用於主鍵的查詢沒試過
//Get請求,查詢user資訊
@GetMapping("/select_user_info/{id}")
public Object searchOneDataByCardNo(@PathVariable int id) {
User user = new User();
user.setId(id);
List<User> list = userMapper.select(user);
return list;
//return selsetOne.toString();
}
//根據id查詢user表和role表
@RequestMapping("/select/{id}")
public Object searchUserAndRoleById(@PathVariable int id){
List<UserRole> listUser =userService.getUserRoleByUserId(id);
return listUser;
}
//插入一條資料
@PostMapping("/insert")
public String insertOneDate(@RequestParam String name,
@RequestParam String age,
@RequestParam String cardNo,
@RequestParam String sDate,
@RequestParam int roleId) {
try {
User user = new User();
user.setName(name);
user.setAge(Integer.parseInt(age));
user.setCardNo(Integer.parseInt(cardNo));
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
user.setBirthday(sdf.parse(sDate));
user.setrId(roleId);
userMapper.insertSelective(user);
return "插入資料成功:" + user.toString();
} catch (ParseException e) {
e.printStackTrace();
return "ERROR!";
}
}
//用姓名刪除資料
@PostMapping("/deleteByName")
public String deleteByName(String name) {
User user = new User();
user.setName(name);
userMapper.delete(user);
return "刪除成功";
}
//按主鍵刪除
@PostMapping("/deleteById")
public String deleteById(String id) {
userMapper.deleteByPrimaryKey(Integer.parseInt(id));
return "刪除成功";
}
//更新資料
@PostMapping("/updateById")
public String updateById(@RequestParam String id,
@RequestParam String name,
@RequestParam int age,
@RequestParam int cardNo,
@RequestParam String sDate,
@RequestParam int roleId) {
try {
User user = new User();
user.setId(Integer.parseInt(id));
user.setName(name);
user.setAge(age);
user.setCardNo(cardNo);
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
user.setBirthday(sdf.parse(sDate));
user.setrId(roleId);
userMapper.updateByPrimaryKeySelective(user);
return "更新完成:" + user.toString();
} catch (ParseException e) {
e.printStackTrace();
return "ERROR!";
}
}
}
第一次邊學邊用所寫,最好用Json返回資料,傳入引數過多同樣推薦使用Json,而不是String,List等; controller裡最好不要用try/catch,try/catch在不知道會出現什麼異常時使用較為適宜,而在controller中大概瞭解會出現那個型別的異常; 增刪改時推薦使用post請求(PostMapping),查詢時推薦使用get請求(GetMapping),區別如下: GET和POST兩種基本請求方法的區別(他講的比我講的有趣) PS:命名不規範,不要學我。
5. 對映檔案實現多表查詢
(1). service
UserService.java
import com.cdqd.app.entity.UserRole;
import java.util.List;
public interface UserService {
List<UserRole> getUserRoleByUserId(int id);
}
service訪問介面 UserServiceImpl.java
package com.cdqd.app.service;
import com.cdqd.app.entity.UserRole;
import com.cdqd.app.mapper.UserMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import java.util.List;
@Service
public class UserServiceImpl implements UserService {
@Autowired
UserMapper userMapper;
@Override
public List<UserRole> getUserRoleByUserId(int id) {
return userMapper.getUserRoleByUserId(id);
}
}
service呼叫mapper實現功能
(2). mapper對映檔案
userRoleMapper.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.cdqd.app.mapper.UserMapper">
<resultMap id="UserResultMap" type="com.cdqd.app.entity.UserRole">
<id column="id" property="id" jdbcType="INTEGER"/>
<result column="role_id" property="roleId" jdbcType="INTEGER"/>
<result column="role_name" property="roleName" jdbcType="VARCHAR"/>
<result column="atk" property="atk" jdbcType="INTEGER"/>
<result column="armor" property="armor" jdbcType="INTEGER"/>
<result column="penetrate" property="penetrate" jdbcType="INTEGER"/>
<result column="name" property="name" jdbcType="VARCHAR"/>
<result column="age" property="age" jdbcType="INTEGER"/>
<result column="card_no" property="cardNo" jdbcType="INTEGER"/>
<result column="birthday" property="birthday" jdbcType="DATE"/>
<result column="r_id" property="rId" jdbcType="INTEGER"/>
</resultMap>
<!--查詢-->
<select id="getUserRoleByUserId" parameterType="java.lang.Integer" resultMap="UserResultMap">
select
u.*,
r.role_id as role_id,
r.role_name as role_name,
r.atk as atk,
r.armor as armor,
r.penetrate as penetrate
from user u,role r
<where>
u.r_id = r.role_id
and u.id = #{id,jdbcType=INTEGER}
</where>
</select>
</mapper>
mapper:namespace填寫所對應的mapper路徑 resultMap:id為唯一主鍵;column(列) 為資料庫中列名,property(屬性)為Java實體類中屬性名 select:id的值為對應mapper的對應方法名;parameterType引數型別;resultMap和上面相結合操作需要的資料
6.程式入口
Application.java
import com.cdqd.app.common.WebUtils;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import tk.mybatis.spring.annotation.MapperScan;
import javax.servlet.http.HttpServletRequest;
@SpringBootApplication
@EnableEurekaClient
@RestController
@MapperScan("com.cdqd.app.mapper" )
@ComponentScan(basePackages="com.cdqd.app")
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
MapperScan用於掃描mapper,此處填了UserMapper所在包名