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