mysql 基础（三）- springboot项目连接mysql

mysql 基础（三）- springboot项目连接mysql

一、通过Idea脚手架搭建springboot项目

1、在idea工具中安装插件 Alibaba Cloud Toolkit

2、创建新项目

下一步

选择springWeb

完成

3、得到项目

启动项目

启动成功

访问页面

二、集成springboot 与 mybits 集成

该例子仅仅是进行一个简单的集成

1、在pom.xml文件中添加依赖文件

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <spring-boot.version>2.6.13</spring-boot.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!-- mybatis 依赖 -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.0.0</version>
        </dependency>
        <!-- mysql 连接类 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <!-- druid 数据库连接池-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.9</version>
        </dependency>
        <!-- lombok 插件 用于简化实体代码 -->
        <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>org.hibernate.javax.persistence</groupId>
            <artifactId>hibernate-jpa-2.1-api</artifactId>
            <version>1.0.0.Final</version>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>${spring-boot.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>${spring-boot.version}</version>
                <configuration>
                    <mainClass>com.example.demo.DemoApplication</mainClass>
                    <skip>true</skip>
                </configuration>
                <executions>
                    <execution>
                        <id>repackage</id>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

2、按照图片创造目录结构

3、各个文件内容

1、StudentController

package com.example.demo.demos.mybatis.controller;

import com.example.demo.demos.mybatis.domain.Student;
import com.example.demo.demos.mybatis.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
@RequestMapping("/Student")
public class StudentController {

    @Autowired
    private StudentService studentService;

    @PostMapping("")
    public int add(@RequestBody Student student){
        return studentService.add(student);
    }

    @PutMapping("/{id}")
    public int updateStudent(@PathVariable("id") Integer id, @RequestParam(value = "name", required = true) String name,
                             @RequestParam(value = "age", required = true) Integer age){
        return studentService.update(name,age,id);
    }

    @DeleteMapping("/{id}")
    public void deleteStudent(@PathVariable("id") Integer id){
        studentService.delete(id);
    }

    @GetMapping("/{id}")
    public Student findStudentById(@PathVariable("id") Integer id){
        return studentService.findStudentById(id);
    }

    @GetMapping("/list")
    public List<Student> findStudentList(){
        return studentService.findStudentList();
    }
}

2、studentMapper

package com.example.demo.demos.mybatis.dao;

import java.util.List;

import com.example.demo.demos.mybatis.domain.Student;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;

@Mapper
public interface StudentMapper {

    @Insert("insert into student(name, age) values(#{name}, #{age})")
    int add(Student student);

    @Update("update student set name = #{name}, age = #{age} where id = #{id}")
    int update(@Param("name") String name, @Param("age") Integer age, @Param("id") Integer id);

    @Delete("delete from student where id = #{id}")
    int delete(int id);

    @Select("select id, name as name, age as age from student where id = #{id}")
    Student findStudentById(@Param("id") Integer id);

    @Select("select id, name as name, age as age from student")
    List<Student> findStudentList();
}

3、student

package com.example.demo.demos.mybatis.domain;

import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Student {

    @Id
    @GeneratedValue
    private Integer id;

    private String name;

    private Integer age;

}

注解：
@Data：可以自动为类生成常用的方法，包括 getter、setter、equals、hashCode 和 toString 等
@NoArgsConstructor: 自动生成无参数构造函数。
@AllArgsConstructor: 自动生成全参数构造函数。
@Id ：标识实体类中的主键字段
@GeneratedValue：为一个实体生成一个唯一标识的主键、提供主键的生成策略

4、studentServiceImpl

package com.example.demo.demos.mybatis.service.impl;

import java.util.List;

import com.example.demo.demos.mybatis.dao.StudentMapper;
import com.example.demo.demos.mybatis.domain.Student;
import com.example.demo.demos.mybatis.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class StudentServiceImpl implements StudentService {

    @Autowired
    private StudentMapper studentMapper;

    /**
     * 添加 Student
     * @param name
     * @param age
     * @return
     */
    @Override
    public int add(Student student) {
        return studentMapper.add(student);
    }

    /**
     * 更新 Student
     * @param name
     * @param age
     * @param id
     * @return
     */
    @Override
    public int update(String name, Integer age, Integer id) {
        return studentMapper.update(name,age,id);
    }

    /**
     * 删除 Student
     * @param id
     * @return
     */
    @Override
    public int delete(Integer id) {
        return studentMapper.delete(id);
    }

    /**
     * 根据 id 查询 Student
     * @param id
     * @return
     */
    @Override
    public Student findStudentById(Integer id) {
        return studentMapper.findStudentById(id);
    }

    /**
     * 查询所有的 Student
     * @return
     */
    @Override
    public List<Student> findStudentList() {
        return studentMapper.findStudentList();
    }
}

5、StudentService

package com.example.demo.demos.mybatis.service;

import com.example.demo.demos.mybatis.domain.Student;

import java.util.List;

public interface StudentService {

    int add(Student student);

    int update(String name, Integer age, Integer id);

    int delete(Integer id);

    Student findStudentById(Integer id);

    List<Student> findStudentList();

}

有爆红的地方引入相应的包即可

6、配置文件 application.properties

# 应用服务 WEB 访问端口
server.port=8082
spring.datasource.url=jdbc:mysql://localhost:3306/test
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

4、在navicat中操作数据库

1、新建test数据库

2、点击”新建查询“新建表，并插入数据

CREATE TABLE `student` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(20) NOT NULL,
  `age` double DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8;
INSERT INTO `student` VALUES ('1', 'aaa', '21');
INSERT INTO `student` VALUES ('2', 'bbb', '22');
INSERT INTO `student` VALUES ('3', 'ccc', '23');

三、演示

Controller 文件中 对应的GetMapping，DeleteMapping，PutMapping、PostMapping 请求需要postman进行相应的测试
这里演示GetMapping