[Java] Use IntelliJ IDEA to build the SSM (MyBatis-Plus) framework and connect to the MySQL database

0 preparation

1. Download and install IntelliJ IDEA
2. Download and install MySQL database
3. Download and installPostman testing tool
4. Create a MySQL database using Navicat

1 Create a Maven project

1. Open IntelliJ IDEA and select "File" → "New" → "Project".
2. Select "Maven" as the project type, and set the project name and project location.
3. Set the Group Id and Artifact Id, and click "Create" to create the project.
   

2 Configure Maven dependencies

Add dependencies for SpringBoot, MyBatis-Plus, etc. in the pom.xml file:

<?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>
  <!-- 定义父项目，使用Spring Boot 的版本管理 -->
  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.7.17</version>
    <relativePath/> <!-- lookup parent from repository -->
  </parent>
  <!-- 项目的基本信息 -->
  <groupId>com.z</groupId>
  <artifactId>MySSM</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>MySSM</name>
  <description>MySSM</description>
  <!-- 定义Java版本 -->
  <properties>
    <java.version>1.8</java.version>
  </properties>
  <dependencies>
    <!-- Spring Boot Web Starter，包含了Spring MVC等 -->
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <!-- MyBatis Spring Boot Starter -->
    <dependency>
      <groupId>org.mybatis.spring.boot</groupId>
      <artifactId>mybatis-spring-boot-starter</artifactId>
      <version>2.3.1</version>
    </dependency>
    <!-- MySQL Connector Java -->
    <dependency>
      <groupId>com.mysql</groupId>
      <artifactId>mysql-connector-j</artifactId>
      <scope>runtime</scope>
    </dependency>
    <!-- Lombok，简化Java代码 -->
    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <optional>true</optional>
    </dependency>
    <!-- Spring Boot Starter Test -->
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
    </dependency>
    <!-- MyBatis-Plus Starter -->
    <dependency>
      <groupId>com.baomidou</groupId>
      <artifactId>mybatis-plus-boot-starter</artifactId>
      <version>3.4.3</version>
    </dependency>
    <!-- Swagger Annotations -->
    <dependency>
      <groupId>io.swagger</groupId>
      <artifactId>swagger-annotations</artifactId>
      <version>1.5.22</version>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
        <configuration>
          <image>
            <builder>paketobuildpacks/builder-jammy-base:latest</builder>
          </image>
          <excludes>
            <exclude>
              <groupId>org.projectlombok</groupId>
              <artifactId>lombok</artifactId>
            </exclude>
          </excludes>
        </configuration>
      </plugin>
    </plugins>
  </build>

</project>

Use the Maven tool or IDEA's automatic build function to download dependencies.

If the following error occurs:

Then click Maven Settings and select the Maven main path as the local Maven download path:

3 Configure data source

Configure database connection and other information in the application.yml file:

server:
  # 端口
  port: 8080

spring:
  # 数据源配置
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/your_database_name?characterEncoding=utf-8
    username: your_username
    password: your_password
  jackson:
    time-zone: GMT+8
    date-format: yyyy-MM-dd HH:mm:ss


mybatis-plus:
  # mapper文件映射路径
  mapper-locations: classpath*:mapper/*.xml
  configuration:
    # 打印SQL语句
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

Replace your_database_name, your_username, your_password in the above example with the information and data in the actual database.

4 Project structure

The project structure is shown below:

5 Create entity class

Create an entity class (entity), such as Student.java:

package com.z.entity;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import io.swagger.annotations.ApiModelProperty;
import lombok.Data;

import java.io.Serializable;

@Data
@TableName("student")
public class Student implements Serializable {
    
    
    private static final long serialVersionUID = 1L;

    /**id*/
    @TableId(type = IdType.AUTO)
    @ApiModelProperty(value = "id")
    private Integer id;

    @ApiModelProperty(value = "姓名")
    private String name;

    @ApiModelProperty(value = "性别")
    private String sex;

    @ApiModelProperty(value = "年龄")
    private Integer age;

    @ApiModelProperty(value = "专业")
    private String major;
}

6 Create the data access layer

Create a data access layer (mapper), such as StudentMapper.java:

package com.z.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.z.entity.Student;
import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface StudentMapper extends BaseMapper<Student> {
    
    
}

Create the corresponding XML file:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.z.mapper.StudentMapper">
</mapper>

7 Create service layer

Create the service layer (service) and its implementation, such as StudentService.java:

Service layer:

package com.z.service;

import com.baomidou.mybatisplus.extension.service.IService;
import com.z.entity.Student;

public interface StudentService extends IService<Student> {
    
    
}

Service implementation layer:

package com.z.service.impl;

import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.z.entity.Student;
import com.z.mapper.StudentMapper;
import com.z.service.StudentService;
import org.springframework.stereotype.Service;

@Service
public class StudentServiceImpl extends ServiceImpl<StudentMapper, Student> implements StudentService {
    
    

}

8 Create Controller layer

Create a Controller layer to process business logic, such as StudentController.java (take returning a data list as an example):

package com.z.controller;

import com.z.entity.Student;
import com.z.service.StudentService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.List;

@RestController
@RequestMapping("/test")
public class StudentController {
    
    
    @Autowired
    private StudentService studentService;

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

9 Start the project

Write Main.java to run the project and start the project through IDEA's start button:

package com.z;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Main {
    
    
    public static void main(String[] args) {
    
    
        SpringApplication.run(Main.class, args);
    }
}

10 Use Postman to test the interface

1. Create a new data table student in the MySQL database, which stores several pieces of test data:
   

2. Open Postman, create a new Get request, and enter the request URL in the corresponding Controller for testing. The test results are as follows:
   
   The front-end interface can display the data in the data table through this interface.