Spring Boot项目快速创建-开发流程（笔记）

主要流程：

前端发送网络请求->controller->调用service->操纵mapper->操作数据库->对entity数据对象赋值->返回前端

前期准备：

maven、mysql下载好 

跟学视频，感谢老师： https://www.bilibili.com/video/BV1gm411m7i6/?share_source=copy_web&vd_source=92d754038ee61d01dacfbb2bacae8320

打点：

00:00 - 42:53 GET接口

42:54 - 51:24 POST接口

51:25 - 54:20 DELETE接口

54:21 - 1:02:11 UPDATE接口

1:02:17 - 1:04:22 打包 

一、项目创建 

初始化Spring boot应用：Spring Initializr

配置好以下内容（根据实际情况选择java版本） ，点GENERATE生成项目。

解压项目之后，idea打开open，导入项目的pom.xml文件。

 

项目结构，源代码全部放在JAVA文件夹下

因为还没有数据库，所以先把pom.xml里数据库的部分注释掉（不然会报错）

然后刷新一下maven，手动reload一下

接下来尝试运行，打开java文件，点击三角，运行main方法

 

可以看见运行起来

右键创建一个测试的controller，编写代码然后运行。

 

package com.example.demo;import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;@RestController
public class TestController {@GetMapping ("/hello")public String hello() {return "Hello World";}
}

运行后，浏览器访问localhost:8080/hello

​基本概念

• **@Controller**：标记类为 Spring MVC 控制器，处理 HTTP 请求并返回视图（如 HTML）。
• ​**@ResponseBody**：将方法的返回值直接写入 HTTP 响体中，而非渲染视图。
• ​**@RestController** = @Controller + @ResponseBody，​专用于 RESTful API，自动将返回对象转为 JSON/XML 格式。

核心功能

• 通过 @RequestMapping、@GetMapping、@PostMapping 等注解绑定 URL 路径。

改为List： 

package com.example.demo;import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;import java.util.List;@RestController
public class TestController {@GetMapping ("/hello")public List<String> hello() {return List.of("Hello","World");}
}

显示JSON格式 ：

 

 二、rest api规范

8个HTTP方法：

GET
POST
PUT
DELETE
OPTIONS
HEAD
TRACE
CONNECT

1.创建数据库 

启动数据库：net start mysql

登录数据库：mysql -uroot -p1234（-u和-p后写自己的用户名和密码）

//创建数据库
create database testcharacter set utf8mb4collate utf8mb4_general_ci//选中该数据库
use test;//创建数据表
create table student(id int auto_increment primary key,name varchar(50) not null,phone char(11) not null,age int
);//插入一条数据
insert into student (name,phone,age)
values('TOM','12345678910',30);

2.写实际代码

①GET接口

恢复上面注释的依赖

新建对应的package，在package里新建接口StudentRepository：

 

再建一个学生类： 

//Student.java
package com.example.demo.dao;import jakarta.persistence.*;@Entity
@Table(name="student")
public class Student {@Id@Column(name = "id")@GeneratedValue(strategy = GenerationType.IDENTITY)private long id;@Column(name = "name")private String name;@Column(name = "phone")private String phone;@Column(name = "age")private int age;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 String getPhone() {return phone;}public void setPhone(String phone) {this.phone = phone;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}
}

//StudentRepository.java
package com.example.demo.dao;import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;@Repository
public interface StudentRepository extends JpaRepository<Student,Long> {}

然后再创建一个package，写service层，同样新建一个接口文件StudentService，以及对应的一个实现StudentServiceImpl

现在目录是这个格式：

//StudentServiceImpl.java
package com.example.demo.service;import com.example.demo.dao.Student;
import com.example.demo.dao.StudentRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;@Service
public class StudentServiceImpl implements StudentService {@Autowiredprivate StudentRepository studentRepository;@Overridepublic Student getStudentById(long id) {return studentRepository.findById(id).orElseThrow(RuntimeException::new);}
}

//StudentService.java
package com.example.demo.service;import com.example.demo.dao.Student;public interface StudentService {public Student getStudentById(long id);}

接下来写对应的api层controller的代码，新建package名为controller，包里建StudentController类。

package com.example.demo.controller;import com.example.demo.dao.Student;
import com.example.demo.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;@RestController
public class StudentController {@Autowiredprivate StudentService studentService;@GetMapping("/student/{id}")public Student getStudent(@PathVariable long id) {return studentService.getStudentById(id);}
}

配置数据库url（用户名和密码写自己的）：

spring.datasource.url=jdbc:mysql://localhost:3306/test?characterEncoding=utf-8
spring.datasource.username=root
spring.datasource.password=1234

在浏览器中输入  localhost:8080/student/1

返回信息： 

 

---

因为controller直接返回了这些值不够规范，有些加密字段是不想展示给前端的，比如这里将年龄保密，不显示。

所以新建一个dto的package以及StudentDTO对象，用来展示可以给前端的数据。

package com.example.demo.dto;public class StudentDTO {private long id;private String name;private String phone;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 String getPhone() {return phone;}public void setPhone(String phone) {this.phone = phone;}
}

修改controller层和service层 ：

package com.example.demo.controller;import com.example.demo.Response;
import com.example.demo.dao.Student;
import com.example.demo.dto.StudentDTO;
import com.example.demo.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;@RestController
public class StudentController {@Autowiredprivate StudentService studentService;@GetMapping("/student/{id}")public Response<StudentDTO> getStudent(@PathVariable long id) {return Response.newSuccess(studentService.getStudentById(id));}
}

package com.example.demo.service;import com.example.demo.dao.Student;
import com.example.demo.dto.StudentDTO;public interface StudentService { StudentDTO getStudentById(long id);
}

package com.example.demo.service;import com.example.demo.converter.StudentConverter;
import com.example.demo.dao.Student;
import com.example.demo.dao.StudentRepository;
import com.example.demo.dto.StudentDTO;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;@Service
public class StudentServiceImpl implements StudentService {@Autowiredprivate StudentRepository studentRepository;@Overridepublic StudentDTO getStudentById(long id) {Student student= studentRepository.findById(id).orElseThrow(RuntimeException::new);return StudentConverter.convertStudent(student);}
}

新建package和类：

package com.example.demo.converter;import com.example.demo.dao.Student;
import com.example.demo.dto.StudentDTO;public class StudentConverter {public static StudentDTO convertStudent(Student student) {StudentDTO studentDTO = new StudentDTO();studentDTO.setId(student.getId());studentDTO.setName(student.getName());studentDTO.setPhone(student.getPhone());return studentDTO;}
}

新建一个Response类，统一一些后端访问的格式：

package com.example.demo;public class Response <T>{private T data;private boolean success;private String errorMsg;public static <K> Response<K> newSuccess(K data) {Response<K> response = new Response<>();response.setData(data);response.setSuccess(true);return response;}public static Response<Void> newFail(String errorMsg) {Response<Void> response = new Response<>();response.setErrorMsg(errorMsg);response.setSuccess(false);return response;}public T getData() {return data;}public void setData(T data) {this.data = data;}public boolean isSuccess() {return success;}public void setSuccess(boolean success) {this.success = success;}public String getErrorMsg() {return errorMsg;}public void setErrorMsg(String errorMsg) {this.errorMsg = errorMsg;}
}

 把代码都修改完之后启动，可以看见age隐藏了没有显示。返回成功。

 

以上是完整的GET查询接口的实现，用来查询id=1的学生信息。

---

②POST接口

接下来新增一个POST接口，用来新增学生信息。

目的：将前端传来的json文件转为Java对象存储至数据库。因为传过来的DTO，所以需要converter，之所以返回getbyid，因为这个方法返回是Long。

编写代码，在原有文件上新增就行，以下复制完整的：

package com.example.demo.controller;import com.example.demo.Response;
import com.example.demo.dao.Student;
import com.example.demo.dto.StudentDTO;
import com.example.demo.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;@RestController
public class StudentController {@Autowiredprivate StudentService studentService;@GetMapping("/student/{id}")public Response<StudentDTO> getStudent(@PathVariable long id) {return Response.newSuccess(studentService.getStudentById(id));}@RequestMapping("/student")@PostMapping("/student")public Response<Long> addNewStudent(@RequestParam StudentDTO studentDTO) {return Response.newSuccess(studentService.addNewStudent(studentDTO));}
}

package com.example.demo.service;import com.example.demo.dao.Student;
import com.example.demo.dto.StudentDTO;public interface StudentService {StudentDTO getStudentById(long id);Long addNewStudent(StudentDTO studentDTO);
}

package com.example.demo.service;import com.example.demo.converter.StudentConverter;
import com.example.demo.dao.Student;
import com.example.demo.dao.StudentRepository;
import com.example.demo.dto.StudentDTO;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.util.CollectionUtils;import java.util.List;@Service
public class StudentServiceImpl implements StudentService {@Autowiredprivate StudentRepository studentRepository;@Overridepublic StudentDTO getStudentById(long id) {Student student= studentRepository.findById(id).orElseThrow(RuntimeException::new);return StudentConverter.convertStudent(student);}@Overridepublic Long addNewStudent(StudentDTO studentDTO) {List<Student> studentList=studentRepository.findByPhone(studentDTO.getPhone());if (!CollectionUtils.isEmpty(studentList)){throw new IllegalStateException("phone:"+studentDTO.getPhone()+" has been taken");}Student student=studentRepository.save(StudentConverter.convertStudent(studentDTO));return student.getId();}
}

package com.example.demo.converter;import com.example.demo.dao.Student;
import com.example.demo.dto.StudentDTO;public class StudentConverter {public static StudentDTO convertStudent(Student student) {StudentDTO studentDTO = new StudentDTO();studentDTO.setId(student.getId());studentDTO.setName(student.getName());studentDTO.setPhone(student.getPhone());return studentDTO;}public static Student convertStudent(StudentDTO studentDTO) {Student student = new Student();student.setName(studentDTO.getName());student.setPhone(studentDTO.getPhone());return student;}
}

package com.example.demo.dao;import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;import java.util.List;@Repository
public interface StudentRepository extends JpaRepository<Student,Long> {List<Student> findByPhone(String phone);
}

 修改完代码就可以使用Postman工具新增学生信息（没有下载所以跳过这步了）

---

③DELETE接口

接下来实现DELETE删除接口。

在原有文件新增就行，新增代码如下：

//StudentController@DeleteMapping("/student/{id}")public void deleteStudentById(@PathVariable long id) {studentService.deleteStudentById(id);}//StudentService
void deleteStudentById(long id);//StudentServiceImpl@Overridepublic void deleteStudentById(long id) {studentRepository.findById(id).orElseThrow(() -> new IllegalArgumentException("id:"+ id +"doesn't exist!"));studentRepository.deleteById(id);}

接下来也是使用postman来删除和查询。（没下载所以又跳过这步，之后如果下载了再来补） 

---

④UPDATE接口

接下来实现UPDATE接口。

在原有文件新增代码如下：

//StudentController@PutMapping("/student/{id}")public Response<StudentDTO> updateStudentById(@PathVariable long id, @RequestParam (required = false)String name,@RequestParam(required = false)String phone) {return Response.newSuccess(studentService.updataStudentById(id,name,phone));}//StudentService
StudentDTO updataStudentById(long id, String name, String phone);//StudentServiceImpl@Override@Transactionalpublic StudentDTO updataStudentById(long id, String name, String phone) {Student studentInDB=studentRepository.findById(id).orElseThrow(() -> new IllegalArgumentException("id:"+ id +"doesn't exist!"));if(StringUtils.hasLength(name) && !studentInDB.getName().equals(name)){studentInDB.setName(name);}if(StringUtils.hasLength(phone) && !studentInDB.getPhone().equals(phone)){studentInDB.setPhone(phone);}Student student=studentRepository.save(studentInDB);return StudentConverter.convertStudent(student);}

接下来也是使用postman来更新和查询。

三、打包项目 

使用命令：mvn clean install 

 

但是出现错误：

错误信息：

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-clean-plugin:3.4.1:clean (default-clean) on project demo: The plugin org.apache.maven.plugins:maven-clean-plugin:3.4.1 requires Maven version 3.6.3 -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/PluginIncompatibleException

原因是当前maven版本为3.6.1，但项目依赖 Spring Boot 3.4.4，官方要求 ​Maven 3.8.8+ 或 ​Java 21+。

重新下载更高级的maven版本：Welcome to Apache Maven – Maven

下载教程：Maven下载以及项目创建（笔记）_maven 依赖 如何下载 com.github-CSDN博客

需要注意！重新配置maven环境变量时，最好删除原来的MAVEN_HOME，重新添加，不然不会更新。 

IDEA重新配置maven路径，重启：

可以看到已经将版本更新了 

使用命令：mvn clean install ，成功啦！！

复制一下jar包路径

 

可以用java -jar demo-0.0.1-SNAPSHOT.jar来启动项目：  

---

以上，总结：

---

完结撒花，零基础，耗时7小时。