SpringBoot项目实现增删改查

接上一章：Java 连接MySql_原你是阳光(#`O′)的博客-CSDN博客，实现单表增删改查

引入依赖

    
    
        org.springframework.boot
        spring-boot-starter-web
        2.6.5
    

    
    
        mysql
        mysql-connector-java
        8.0.28
    

    
    
        org.mybatis.spring.boot
        mybatis-spring-boot-starter
        2.2.2
    

    
    
        org.springframework.boot
        spring-boot-starter-test
        2.6.5
    

application.yml配置

server:
  #端口号
  port: 9527
spring:
  #数据库配置
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/test1?useUnicode=true&characterEncoding=utf8&zeroDateTimeBehavior=convertToNull&useSSL=true&serverTimezone=GMT%2B8
    username: root
    password: 123456
# MyBatis配置
mybatis:
  mapper-locations: com/thk/mapper/*Mapper.xml
 

实体类：

public class People {
    /**
     * id
     */
    private Long id;
    /**
     * 姓名
     */
    private String name;
    /**
     * 年龄
     */
    private Integer age;
    /**
     * 地址
     */
    private String address;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "People{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", address='" + address + '\'' +
                '}';
    }
    
}

生成id雪花算法工具类

package com.thk.utils;

/**
 * 分布式唯一ID 雪花算法实现
 */
public class SnowFlake {
    /**
     * 起始的时间戳  
     */
    private final static long START_TIMESTAMP = 1593446400L;

    /**
     * 每一部分占用的位数
     */
    private final static long SEQUENCE_BIT = 12; //序列号占用的位数
    private final static long MACHINE_BIT = 5;   //机器标识占用的位数
    private final static long DATA_CENTER_BIT = 5;//数据中心占用的位数

    /**
     * 每一部分的最大值
     */
    private final static long MAX_DATA_CENTER_NUM = -1L ^ (-1L << DATA_CENTER_BIT);
    private final static long MAX_MACHINE_NUM = -1L ^ (-1L << MACHINE_BIT);
    private final static long MAX_SEQUENCE = -1L ^ (-1L << SEQUENCE_BIT);

    /**
     * 每一部分向左的位移
     */
    private final static long MACHINE_LEFT = SEQUENCE_BIT;
    private final static long DATA_CENTER_LEFT = SEQUENCE_BIT + MACHINE_BIT;
    private final static long TIMESTAMP_LEFT = DATA_CENTER_LEFT + DATA_CENTER_BIT;

    /**
     * 数据中心编码，初始化后不可修改
     * 最大值: 2^5-1 取值范围: [0,31]
     */
    private long dataCenterId;

    /**
     * 机器或进程编码，初始化后不可修改
     * 最大值: 2^5-1 取值范围: [0,31]
     */
    private long machineId;

    /**
     * 序列号
     * 最大值: 2^12-1 取值范围: [0,4095]
     */
    private long sequence = 0L;

    private long lastStamp = -1L;//上一次时间戳

    public SnowFlake(long dataCenterId, long machineId) {
        if (dataCenterId > MAX_DATA_CENTER_NUM || dataCenterId < 0) {
            throw new IllegalArgumentException("dataCenterId can't be greater than MAX_DATA_CENTER_NUM or less than 0");
        }
        if (machineId > MAX_MACHINE_NUM || machineId < 0) {
            throw new IllegalArgumentException("machineId can't be greater than MAX_MACHINE_NUM or less than 0");
        }
        this.dataCenterId = dataCenterId;
        this.machineId = machineId;
    }

    /**
     * 产生下一个ID
     *
     * @return
     */
    public synchronized long nextId() {
        //获取当前时间戳 可用System.currentTimeMillis(); 方法替换
        long currStamp = getNewStamp();
        //保证当前时间戳不小于最后一次的时间戳
        if (currStamp < lastStamp) {
            throw new RuntimeException("Clock moved backwards.  Refusing to generate id");
        }
        //如果当前时间戳等于最后一次时间戳 就进行序号递增
        if (currStamp == lastStamp) {
            //相同毫秒内，序列号自增
            sequence = (sequence + 1) & MAX_SEQUENCE;
            //同一毫秒的序列数已经达到最大
            if (sequence == 0L) {
                currStamp = getNextMill();
            }
        } else {
            //不同毫秒内，序列号置为0
            sequence = 0L;
        }
        //保存最后一次时间戳
        lastStamp = currStamp;
        //通过位运算，将相应的二进制数值放到对应的位置  41位时间戳 + 5位数据中心 + 5位机器码 + 12位序列号 ，首位没有使用
        return (currStamp - START_TIMESTAMP) << TIMESTAMP_LEFT //时间戳部分
                | dataCenterId << DATA_CENTER_LEFT       //数据中心部分
                | machineId << MACHINE_LEFT             //机器标识部分
                | sequence;                             //序列号部分
    }

    private long getNextMill() {
        //获取当前时间戳
        long mill = getNewStamp();
        //获取大于上一次时间戳的时间戳
        while (mill <= lastStamp) {
            mill = getNewStamp();
        }
        return mill;
    }

    /**
     * 获取当前时间戳
     */
    private long getNewStamp() {
        return System.currentTimeMillis();
    }

}

controller

package com.thk.controller;

import com.thk.domain.People;
import com.thk.service.IPeopleService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import javax.websocket.server.PathParam;
import java.util.List;

@RestController
public class PeopleController {
    @Autowired
    private IPeopleService peopleService;

    /**
     * 查询全部用户
     *
     * @param people
     * @return
     */
    @GetMapping("/selectAll")
    public List selectAll(People people) {
        return peopleService.selectAll(people);
    }

    /**
     * 增加用户或者修改用户
     *
     * @param people
     * @return
     */
    @PostMapping("/people")
    public int people(@RequestBody People people) throws Exception {
        return peopleService.people(people);
    }

    /**
     * 根据id查询一条数据
     *
     * @param id
     * @return
     */
    @GetMapping("/selectOne/{id}")
    public People selectOne(@PathVariable Long id) {
        return peopleService.selectOne(id);
    }

    /**
     * 删除数据
     * @param id
     * @return
     */
    @DeleteMapping("/delPeople/{id}")
    public int delPeople(@PathVariable Long id) throws Exception{
        return peopleService.delPeople(id);
    }

}

service

public interface IPeopleService {
    /**
     * 查询全部用户
     *
     * @param people
     * @return
     */
    List selectAll(People people);

    /**
     * 增加用户或者修改用户
     *
     * @param people
     * @return
     */
    int people(People people) throws Exception;

    /**
     * 根据id查询一条数据
     *
     * @param id
     * @return
     */
    People selectOne(Long id);

    /**
     * 删除数据
     * @param id
     * @return
     */
    int delPeople(Long id) throws Exception;
}

service实现类：

@Service
public class PeopleImpl implements IPeopleService {
    @Autowired
    private PeopleMapper peopleMapper;

    /**
     * 查询全部用户
     *
     * @param people
     * @return
     */
    @Override
    public List selectAll(People people) {
        return peopleMapper.selectAll(people);
    }

    /**
     * 增加用户或者修改用户
     *
     * @param people
     * @return
     */
    @Override
    public int people(People people) throws Exception {
        //判断id是否为空，如果为空就是添加
        if (StringUtils.isEmpty(people.getId())) {
            SnowFlake snowFlake = new SnowFlake(2, 3);
            long l = snowFlake.nextId();
            //设置id
            people.setId(l);
            System.out.println("添加的id是" + l);
            //添加数据
            return peopleMapper.addPeople(people);

        } else {
            //如果id不为空，就是修改
            //到数据库查询是否存在这条数据，如果不存在抛出异常
            People people1 = peopleMapper.selectOne(people.getId());
            if (people1 == null) {
                throw new Exception("修改的数据不存在！！！");
            }
            //修改数据
            return peopleMapper.updatePeople(people);
        }
    }

    /**
     * 根据id查询一条数据
     *
     * @param id
     * @return
     */
    @Override
    public People selectOne(Long id) {
        return peopleMapper.selectOne(id);
    }

    /**
     * 删除数据
     *
     * @param id
     * @return
     */
    @Override
    public int delPeople(Long id) throws Exception {
        if (id != null) {
            People people = peopleMapper.selectOne(id);
            if (people != null) {
                //删除数据
                return peopleMapper.delPeople(id);
            } else {
                throw new Exception("修改的数据不存在！！！");
            }
        } else {
            throw new Exception("数据异常！！！");
        }

    }
}

mapper接口

@Mapper
public interface PeopleMapper {
    /**
     * 查询全部用户
     *
     * @param people
     * @return
     */
    List selectAll(People people);

    /**
     * 根据id查询一条数据
     *
     * @param id
     * @return
     */
    People selectOne(Long id);

    /**
     * 添加数据
     *
     * @param people
     * @return
     */
    int addPeople(People people);

    /**
     * 修改数据
     *
     * @param people
     * @return
     */
    int updatePeople(People people);

    /**
     * 删除数据
     *
     * @param id
     * @return
     */
    int delPeople(Long id);
}

mapper.xml

    
    
        SELECT  * FROM  people
    
    
    
        SELECT  * FROM  people where  id =#{id}
    
    
    
        insert  into people(id,name,age,address) values (#{id},#{name},#{age},#{address})
    
    
    
        update people
        
            name = #{name},
            age = #{age},
            address = #{address},
        
        where id = #{id}
    
    
    
         delete from
        people
        where id =#{id}
    

启动程序：

测试添加数据

运行结果：

日志打印：

测试修改数据：

 运行结果：

原数据：

修改后：

 日志打印：

测试查询一条数据

运行结果：

 删除数据

运行结果：

打印日志

查询全部数据，发现添加的数据已经被删除了

以上就是数据库单表额CRUD