springboot的简单学习

1.建一个springboot的简单demo

使用的是idea

勾选需要的依赖 因为打算用mybatis-plus所以没有选mybatis框架来操作数据库

导入上面说的mybatis-plus依赖以及连接mysql的依赖

        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.0.5</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        

设计一下数据库，我用的Navicat，随便搞搞

配置一下application.properties来连接数据库

spring.datasource.driverClassName = com.mysql.cj.jdbc.Driver
spring.datasource.url = jdbc:mysql://localhost:3306/demo?useSSL=false&useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8
spring.datasource.username = 123456
spring.datasource.password = 123456
server.port=3000

接下来建一些包和文件

设计数据库表对应的实体类Demo

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

/**
 * @author ziran
 * @date 2020/12/6-16:34
 */
@AllArgsConstructor
@NoArgsConstructor
@Data
public class Demo {
    private Long id;
    private String name;
    private int sex;
}

设计Demomapper

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.ziran.demo.pojo.Demo;
import org.springframework.stereotype.Repository;

/**
 * @author ziran
 * @date 2020/12/6-19:04
 */
@Repository
public interface DemoMapper extends BaseMapper<Demo> {
}

整个DemoService接口

import com.ziran.demo.pojo.Demo;
import java.util.List;

/**
 * @author ziran
 * @date 2020/12/6-16:39
 */
public interface DemoService {

    /**
     * 得到表中的所以数据
     * @return
     */
    List<Demo> listAll();
}

整个对应的实现类DemoServiceImpl

import javax.annotation.Resource;
import java.util.List;

/**
 * @author ziran
 * @date 2020/12/6-16:40
 */
@Service("DemoService")
public class DemoServiceImpl implements DemoService {

    @Resource
    private DemoMapper demoMapper;

    @Override
    public List<Demo> listAll() {
        return demoMapper.selectList(null);
    }
}

到了这里差不多了，可以先测试一下

import com.ziran.demo.mapper.DemoMapper;
import com.ziran.demo.pojo.Demo;
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;
import javax.annotation.Resource;

import java.util.List;


/**
 * @author ziran
 * @date 2020/12/6-19:07
 */
@SpringBootTest
class DemoServiceImplTest {
    @Resource
    private DemoMapper demoMapper;

    @Test
    void contextLoads() {
        //查询
        List<Demo> demos = demoMapper.selectList(null);
        demos.forEach(System.out::println);
    }

}

看看结果 fine 如果失败也许在DemoAoolication加上点东西

@MapperScan("com.ziran.demo.mapper")//mapper文件所在包的位置

最后补上DemoController

import com.ziran.demo.pojo.Demo;
import com.ziran.demo.service.Impl.DemoServiceImpl;
import org.springframework.web.bind.annotation.*;
import javax.annotation.Resource;
import java.util.List;

/**
 * @author ziran
 * @date 2020/12/6-17:07
 */
@RestController
@CrossOrigin
public class DemoController {
    @Resource
    private DemoServiceImpl demoService;

    @GetMapping("listall")
    public List<Demo> adminLogin(){
        List<Demo> demos = demoService.listAll();
        return demos;
    }

}

好了，一个基于springboot的web项目完成了

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