一、前置

1、IDEA创建SpringBoot项目

• 选择spring Initializr，输入项目名，选择项目路径等，最后点击Next
  
• 勾选Spring Web
  
• 勾选需要使用的数据库驱动，本次demo中使用的是SQL server数据库，故选择SQL server Driver
  
• 选择完后，点击Create

2、基础设置、配置

• 项目创建完成并打开后，按需配置项目Maven
  
• 设置Maven
• 设置完成后等待加载完成

二、JPA查询数据

• 在项目中分别创建好以下包及文件
  

1、配置SQL server连接

• 找到application.properties文件，配置SQL Server 数据库连接

# 应用服务 WEB 访问端口
server.port=8080

spring.datasource.url=jdbc:sqlserver://IP:端口号;databaseName=数据库名
spring.datasource.username=数据库连接用户名
spring.datasource.password=数据库连接密码
spring.datasource.driverClassName=com.microsoft.sqlserver.jdbc.SQLServerDriver

2、创建实体类

QueryEntity.java

package com.example.Entity;

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "tb")      // 数据表名
public class QueryEntity {
    @Id
    // 主键字段
    private Long CID;
    private String CUSTOMER_ITEM_CODE;
    private String CUSTOMER_ITEM_NAME;
    private String ACTUAL_INVENTORY_QTY;

    public Long getCID() {
        return CID;
    }

    public void setCID(Long CID) {
        this.CID = CID;
    }

    public String getCUSTOMER_ITEM_CODE() {
        return CUSTOMER_ITEM_CODE;
    }

    public void setCUSTOMER_ITEM_CODE(String CUSTOMER_ITEM_CODE) {
        this.CUSTOMER_ITEM_CODE = CUSTOMER_ITEM_CODE;
    }

    public String getCUSTOMER_ITEM_NAME() {
        return CUSTOMER_ITEM_NAME;
    }

    public void setCUSTOMER_ITEM_NAME(String CUSTOMER_ITEM_NAME) {
        this.CUSTOMER_ITEM_NAME = CUSTOMER_ITEM_NAME;
    }

    public String getACTUAL_INVENTORY_QTY() {
        return ACTUAL_INVENTORY_QTY;
    }

    public void setACTUAL_INVENTORY_QTY(String ACTUAL_INVENTORY_QTY) {
        this.ACTUAL_INVENTORY_QTY = ACTUAL_INVENTORY_QTY;
    }

    @Override
    public String toString() {
        return "QueryEntity{" +
                "CID=" + CID +
                ", CUSTOMER_ITEM_CODE='" + CUSTOMER_ITEM_CODE + '\'' +
                ", CUSTOMER_ITEM_NAME='" + CUSTOMER_ITEM_NAME + '\'' +
                ", ACTUAL_INVENTORY_QTY='" + ACTUAL_INVENTORY_QTY + '\'' +
                '}';
    }
}

生成Getter and Setter

• 生成toString()
  
  
  

3、创建Repository接口

• 用于处理数据库操作

QueryRepository.java

• 创建时选择Interface
  

package com.example.Repository;

import com.example.Entity.QueryEntity;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
import org.springframework.stereotype.Repository;

import java.util.List;

@Repository
public interface QueryRepository extends JpaRepository<QueryEntity, Long> {
    // 使用方法名查询所有数据
    List<QueryEntity> findAll();

    // 使用 JPQL 自定义查询
    @Query(value = "SELECT CUSTOMER_ITEM_CODE, CUSTOMER_ITEM_NAME, ACTUAL_INVENTORY_QTY FROM [dbo].[tb]", nativeQuery = true)
    List<QueryEntity> findAllByAll();
}

4、创建Service服务类

• 用于处理业务逻辑

QueryService.java

package com.example.Service;

import com.example.Entity.QueryEntity;
import com.example.Repository.QueryRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class QueryService {
    @Autowired
    private QueryRepository queryRepository;

    public List<QueryEntity> getAllSCHubRecords() {
        return queryRepository.findAll();
    }
}

5、创建Controller控制器类

• 用于处理 HTTP 请求

QueryController.java

package com.example.Controller;

import com.example.Entity.QueryEntity;
import com.example.Service.QueryService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
//定义接口
@RequestMapping("/api/schub")
public class QueryController {
    @Autowired
    private QueryService queryService;

    //查询所有数据
    @GetMapping
    public List<QueryEntity> getAllSCHubRecords() {
        return queryService.getAllSCHubRecords();
    }
}

6、测试

运行项目

访问接口

http://localhost:8080/api/schub