[Java知识库]springboot+vue+element+mybatisplus项目(后端)

后端来说的话毕竟只进行了CRUD所以代码量还是很少，很简单的，后端有一些需要特别注意的点！

首页第一步连接数据库配置myabatisPlus需要导入的pom依赖是:

<!--        mybatis-plus-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.3.1</version>
        </dependency>

导入依赖之后在application.properties文件里面写数据库连接等等:

server.port=9090
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/travelmanage?useUnicode=true&characterEncoding=utf-8
spring.datasource.username=travelmanage
spring.datasource.password=travelmanage

mybatisPlus需要一个配置类mybatisPlusConfig

package cn.com.zzn.common;


import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.PaginationInnerInterceptor;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/*
* @description mybatis-plus  分页插件
* */

//Spring boot方式
@Configuration
//扫描包 扫描到接口
@MapperScan("cn.com.zzn.mapper")
public class MybatisPlusConfig {
    /*
    * 分页插件
    * */
    // 最新版
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
//DbType.MYSQL需要设置数据库类型为DbType.MYSQL否者查出来的数据为null
        interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.MYSQL));
        return interceptor;
    }
}

Result封装类

package cn.com.zzn.common;

//Result我们返回给前台数据的一个包装类，后台返回给前台的数据是json,json里面会包含几个属性
public class Result<T> {
    //code告诉前台返回的数据是成功还是失败，失败code就不会是0
    private String code;
    //msg放数据信息
    private String msg;
    //T表示任何一种数据类型都可以被result所包含，定义T可以包含多个表的实体类
    private T data;

    public String getCode() {
        return code;
    }

    public void setCode(String code) {
        this.code = code;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }

    public T getData() {
        return data;
    }

    public void setData(T data) {
        this.data = data;
    }
    public Result(){

    }
    public Result(T data){
        this.data = data;
    }
    public static Result success(){
        Result result = new Result<>();
        result.setCode("0");
        result.setMsg("成功");
        return result;
    }
    public static <T> Result<T> success(T data){
        Result<T> result = new Result<>(data);
        result.setCode("0");
        result.setMsg("成功");
        return result;
    }
    public static Result error(String code,String msg){
        Result result = new Result();
        result.setCode(code);
        result.setMsg(msg);
        return result;
    }
}

实体类层

package cn.com.zzn.entity;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

@TableName("user")  //mybatis-plus需要跟数据库的表名对应
@Data
public class User {
    @TableId(type = IdType.AUTO)//    设置自增
    private Integer id;
    @TableField("userId")
    private String userId;
    @TableField("userPwd")
    private String userPwd;
    private String nickName;
    private Integer age;
    private String sex;
    private String address;
}

实习crud的mapper层

@Repository
public interface UserMapper extends BaseMapper<User> {
}

controller层

import cn.com.zzn.common.Result;
import cn.com.zzn.entity.User;
import cn.com.zzn.mapper.UserMapper;
import cn.hutool.core.util.StrUtil;
import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.toolkit.Wrappers;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import org.springframework.web.bind.annotation.*;

import javax.annotation.Resource;

/**
 * @RequestBody前台传入一个json对象后台将它映射成Java的一个实体
 * */

@RestController
@RequestMapping("/user")
public class UserController {
    //没写业务层不规范
    @Resource
    UserMapper userMapper;
    
    @PostMapping
    public Result<?> save(@RequestBody User user) {
        if (user.getUserPwd() == null){
            user.setUserPwd("123456");
        }
        userMapper.insert(user);
        return Result.success();
    }

    /**
     * search是模糊查询的值
     * */
    @GetMapping
    public Result<?> findPage(@RequestParam(defaultValue = "1") Integer pageNum,
                              @RequestParam(defaultValue = "10") Integer pageSize,
                              @RequestParam(defaultValue = "") String search) {
        LambdaQueryWrapper<User> wrapper = Wrappers.<User>lambdaQuery();
//        isNotBlank判断search不是空
        if (StrUtil.isNotBlank(search)){
            //避免nickName为null的时候查不出来
            wrapper.like(User::getNickName,search);
        }
        //第一个参数传的分页，第二个参数传的模糊查询  ::取属性值
//        Page<User> userPage = userMapper.selectPage(new Page<>(pageNum,pageSize ), Wrappers.<User>lambdaQuery().like(User::getNickName, search));
        Page<User> userPage = userMapper.selectPage(new Page<>(pageNum,pageSize ),wrapper);
        return Result.success(userPage);
    }
}

sql文件

-- auto-generated definition
CREATE TABLE `user`  (
                         `id` int(11) NOT NULL AUTO_INCREMENT COMMENT 'ID',
                         `userId` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NULL DEFAULT NULL COMMENT '用户名',
                         `userPwd` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NULL DEFAULT NULL COMMENT '密码',
                         `nick_name` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NULL DEFAULT NULL COMMENT '昵称',
                         `age` int(11) NULL DEFAULT NULL COMMENT '年龄',
                         `sex` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NULL DEFAULT NULL COMMENT '性别',
                         `address` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci NULL DEFAULT NULL COMMENT '地址',
                         PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 14 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_unicode_ci COMMENT = '用户信息表' ROW_FORMAT = Dynamic;

INSERT INTO `user` VALUES (1, 'admin', 'admin', '管理员', 32, '男', '北京市');
INSERT INTO `user` VALUES (5, '2', NULL, '2', 2, '女', '2');
INSERT INTO `user` VALUES (6, '3', '123456', '3', 3, '未知', '3');
INSERT INTO `user` VALUES (7, '11', NULL, '11', 11, '男', '11');
INSERT INTO `user` VALUES (8, '2', NULL, '2', 2, '女', '2');
INSERT INTO `user` VALUES (10, '11', NULL, '11', 11, '男', '11');
INSERT INTO `user` VALUES (11, '2', NULL, '2', 2, '女', '2');
INSERT INTO `user` VALUES (13, 'zhang', '123', NULL, NULL, NULL, NULL);