springboot+mybatis-plus 实现增删改查_springbootmybatisplus增删改查

一，先采用IDEA构建项目步骤如下




二，项目构建好之后，在pom.xml添加依赖

<dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.5.1</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.2</version>
        </dependency>

    </dependencies>
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第三步，把application.properties修改为application.yaml
在文件中添加如下内容

spring:
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://127.0.0.1:3306/springboot?useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=true&serverTimezone=GMT%2B8&nullCatalogMeansCurrent=true
 # 这是链接数据库的账号
    username: root 
 # 这是链接数据库的密码
    password: root
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第四步 构建目录结构，如下图

第五步，在entity包编写user实体类

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

@Data  // 自动注入set和get方法
@AllArgsConstructor  //自动生成有参构造方法
@NoArgsConstructor   //自动生成无参构造方法
@TableName("user")   //对应的数据表
public class User {
    // 因为数据表的ID是自增的，所以需配置一下
    @TableId(value ="userid" ,type = IdType.AUTO)
    private Integer  userid;
    private String userName;  //对应数据库的字段是 user_name
    private String userPwd;   //对应数据库的字段是 user_pwd
    private String sex;
    private int age;
}
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第六步 在entity包编写mybatisplus分页插件
/**

• 使用这个配置类体添加mybatisplus的分页插件
  */

@Configuration
public class PageConfig {
    @Bean
    public MybatisPlusInterceptor mybatisPlusInterceptor() {
        MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();
        interceptor.addInnerInterceptor(new PaginationInnerInterceptor(DbType.H2));
        return interceptor;
    }

}
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第七 在dao包新建UserMapper接口

第八 在service包新建UserService接口

第九 在impl包中新建UserServiceImpl类

还有一个工具类，返回统一格式

import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.Data;
/**
 * 响应体，主要用来做接口统一返回格式
 */
@Data
public class Result {
    // 定义jackson对象
    private static final ObjectMapper MAPPER = new ObjectMapper();

    // 响应业务状态
    private Integer status;

    // 响应消息
    private String msg;

    // 响应中的数据
    private Object data;

    public Result() {
    }

    public Result(Integer status, String msg, Object data) {
        this.status = status;
        this.msg = msg;
        this.data = data;
    }

    public Result(Object data) {
        this.status = 0;
        this.msg = "OK";
        this.data = data;
    }

    public static Result ok() {
        return new Result(null);
    }

    public static Result ok(Object data) {
        return new Result(data);
    }

    public static Result build(Integer status, String msg) {
        return new Result(status, msg, null);
    }

    public static Result build(Integer status, String msg, Object data) {
        return new Result(status, msg, data);
    }

}
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第十步 新建controller

import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.example.entity.User;
import com.example.service.UserService;
import com.example.utils.Result;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.List;

@RestController
public class UserController {

    @Autowired
    UserService userService;

    @GetMapping("/getAllUser")
    public Page<User> getAllUser() {
        List<User> list = userService.list();
        for (User user : list) {
            System.out.println(user.toString());
        }
        //构建分页对象
        Page<User> userPage = new Page<>(2,2);
        //第一个参数为分页对象，第二个为查询条件（可以不写）
        Page<User> page = userService.page(userPage, null);
        System.out.println("总页码：" + page.getPages());
        System.out.println("总记录数：" + page.getTotal());

        return page;
    }

    /**
     * 根据id获取数据
     * @param
     * @return
     */
    @RequestMapping(value = "/getUserById",method = RequestMethod.POST)
    public Result getUserById(@RequestBody User user){
        User userSelect = userService.getById(user.getUserid());
        return Result.ok(userSelect);
    }

    /**
     * 根据id更新数据
     * @param user
     * @return
     */
    @PostMapping("/update")
    public Result updateById(@RequestBody User user){
        boolean ret = userService.updateById(user);
        if (!ret){
            return Result.build(-1,"更新失败");
        }
        return Result.ok();
    }

    /**
     * 新增用户
     * @param user
     * @return
     */
    @PostMapping("/save")
    public Result saveUser(@RequestBody User user){
        try {
            boolean ret = userService.save(user);
            if (!ret){
                return Result.build(-1,"新增失败");
            }
            return Result.ok();
        } catch (Exception e) {
            return Result.build(-1,e.getMessage());
        }
    }

    /**
     * 删除用户
     * @param user
     * @return
     */
    @PostMapping("/delete")
    public Result deleteUser(@RequestBody User user){
        try {
            boolean ret = userService.removeById(user.getUserid());
            if (!ret){
                return Result.build(-1,"删除失败");
            }
            return Result.ok();
        } catch (Exception e) {
            return Result.build(-1,e.getMessage());
        }
    }




}
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第十一 采用postman进行测试接口

1，查询所有

2，根据ID查询

3，更新

4，根据ID删除

5，添加