五、云对象存储以及课程分类管理模块

本项目的存储图片和音频文件都存储在腾讯云的服务器中，本章先介绍存储图片的方式。

存储桶文件创建：

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存储桶项目存储内容：

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APPID和密钥管理：

APPID和密钥是整个云存储最为重要的验证依据，在配置文件中应用。

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现在简要介绍整个云存储的配置过程（只能指定路径上传存储，密钥隐藏）：

package com.lxl;

import com.alibaba.fastjson.JSON;
import com.qcloud.cos.COSClient;
import com.qcloud.cos.ClientConfig;
import com.qcloud.cos.auth.BasicCOSCredentials;
import com.qcloud.cos.auth.COSCredentials;
import com.qcloud.cos.http.HttpProtocol;
import com.qcloud.cos.model.PutObjectRequest;
import com.qcloud.cos.model.PutObjectResult;
import com.qcloud.cos.region.Region;

import java.io.File;

public class TestCos {

    public static void main(String[] args) {
        // 1 初始化用户身份信息（secretId, secretKey）。
        String secretId = "AKIDQjskRxPgs1HPNl0LSM3c2GF3jGbkiXCh";
        String secretKey = "###############################";
        COSCredentials cred = new BasicCOSCredentials(secretId, secretKey);
        // 2 设置 bucket 的地域, COS 地域的简称请参照 https://cloud.tencent.com/document/product/436/6224
        Region region = new Region("ap-beijing");
        ClientConfig clientConfig = new ClientConfig(region);
        // 这里建议设置使用 https 协议
        clientConfig.setHttpProtocol(HttpProtocol.https);
        // 3 生成 cos 客户端。
        COSClient cosClient = new COSClient(cred, clientConfig);

        // 指定要上传的文件
        File localFile = new File("/Users/xiaolianglu/01.png");
        // 指定文件将要存放的存储桶
        String bucketName = "ggkt-1312247070";
// 指定文件上传到 COS 上的路径，即对象键。例如对象键为folder/picture.jpg，则表示将文件 picture.jpg 上传到 folder 路径下
        String key = "/2022/07/01.png";
        PutObjectRequest putObjectRequest = new PutObjectRequest(bucketName, key, localFile);
        PutObjectResult putObjectResult = cosClient.putObject(putObjectRequest);
        System.out.println(JSON.toJSONString(putObjectResult));
    }
}

配置application.properties方便后续服务器数据调用（密钥隐藏）：

spring.servlet.multipart.max-file-size=1024MB
spring.servlet.multipart.max-request-size=1024MB

tencent.cos.file.region=ap-beijing
tencent.cos.file.secretid=AKIDQjskRxPgs1HPNl0LSM3c2GF3jGbkiXCh
tencent.cos.file.secretkey=############################

tencent.cos.file.bucketname=ggkt-1312247070

创建工具类（将个人数据库数据做转换，作为接口传输数据）：

package com.lxl.ggkt.vod.utils;

import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.stereotype.Component;

@Component
public class ConstantPropertiesUtil implements InitializingBean {

    @Value("${tencent.cos.file.region}")
    private String region;

    @Value("${tencent.cos.file.secretid}")
    private String secretId;

    @Value("${tencent.cos.file.secretkey}")
    private String secretKey;

    @Value("${tencent.cos.file.bucketname}")
    private String bucketName;
    

    public static String END_POINT;
    public static String ACCESS_KEY_ID;
    public static String ACCESS_KEY_SECRET;
    public static String BUCKET_NAME;

    @Override
    public void afterPropertiesSet() throws Exception {
        END_POINT = region;
        ACCESS_KEY_ID = secretId;
        ACCESS_KEY_SECRET = secretKey;
        BUCKET_NAME = bucketName;
    }
}

确定上传流之后，查看对应文档提供的事例，修改默认的KEY_ID和KEY_SECRECT，存储桶APP_ID，修改上传文件路径：

package com.lxl.ggkt.vod.service.impl;

import com.lxl.ggkt.vod.service.FileService;
import com.lxl.ggkt.vod.utils.ConstantPropertiesUtil;
import com.qcloud.cos.COSClient;
import com.qcloud.cos.ClientConfig;
import com.qcloud.cos.auth.BasicCOSCredentials;
import com.qcloud.cos.auth.COSCredentials;
import com.qcloud.cos.http.HttpProtocol;
import com.qcloud.cos.model.ObjectMetadata;
import com.qcloud.cos.model.PutObjectRequest;
import com.qcloud.cos.model.PutObjectResult;
import com.qcloud.cos.region.Region;
import org.joda.time.DateTime;
import org.springframework.stereotype.Service;
import org.springframework.web.multipart.MultipartFile;

import java.io.InputStream;
import java.util.UUID;

@Service
public class FileServiceImpl implements FileService {

    //文件上传
    @Override
    public String upload(MultipartFile file) {
        // 1 初始化用户身份信息（secretId, secretKey）。
        String secretId = ConstantPropertiesUtil.ACCESS_KEY_ID;
        String secretKey = ConstantPropertiesUtil.ACCESS_KEY_SECRET;
        COSCredentials cred = new BasicCOSCredentials(secretId, secretKey);
        // 2 设置 bucket 的地域, COS 地域的简称请参照 https://cloud.tencent.com/document/product/436/6224
        Region region = new Region(ConstantPropertiesUtil.END_POINT);
        ClientConfig clientConfig = new ClientConfig(region);
        // 这里建议设置使用 https 协议
        clientConfig.setHttpProtocol(HttpProtocol.https);
        // 3 生成 cos 客户端。
        COSClient cosClient = new COSClient(cred, clientConfig);

        // 存储桶的命名格式为 BucketName-APPID，此处填写的存储桶名称必须为此格式
        String bucketName = ConstantPropertiesUtil.BUCKET_NAME;
        // 对象键(Key)是对象在存储桶中的唯一标识。  998u-09iu-09i-333
        //在文件名称前面添加uuid值
        String key = UUID.randomUUID().toString().replaceAll("-","")
                +file.getOriginalFilename();
        //对上传文件分组，根据当前日期  /2022/11/11
        String dateTime = new DateTime().toString("yyyy/MM/dd");
        key = dateTime+"/"+key;
        try {
            //获取上传文件输入流
            InputStream inputStream = file.getInputStream();
            ObjectMetadata objectMetadata = new ObjectMetadata();
            PutObjectRequest putObjectRequest = new PutObjectRequest(
                    bucketName,
                    key,
                    inputStream,
                    objectMetadata);
            // 高级接口会返回一个异步结果Upload
            PutObjectResult putObjectResult = cosClient.putObject(putObjectRequest);
            //返回上传文件路径
            //https://ggkt-atguigu-1310644373.cos.ap-beijing.myqcloud.com/01.jpg
            String url = "https://"+bucketName+"."+"cos"+"."+ConstantPropertiesUtil.END_POINT+".myqcloud.com"+"/"+key;
            return url;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }
}

完成对应的FileUploadController.java（上传接口）：

package com.lxl.ggkt.vod.controller;

import com.lxl.ggkt.result.Result;
import com.lxl.ggkt.vod.service.FileService;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import io.swagger.annotations.ApiParam;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;

@Api(tags = "文件上传接口")
@RestController
@RequestMapping("/admin/vod/file")
//@CrossOrigin
public class FileUploadController {

    @Autowired
    private FileService fileService;

    @ApiOperation("文件上传")
    @PostMapping("upload")
    public Result uploadFile(
            @ApiParam(name = "file", value = "文件", required = true)
            @RequestParam("file") MultipartFile file){

        String url = fileService.upload(file);
        return Result.ok(url).message("上传文件成功");
    }
}

课程后端相关设计（列表展示，数据导入，数据导出）：

package com.lxl.ggkt.vod.controller;


import com.lxl.ggkt.model.vod.Subject;
import com.lxl.ggkt.result.Result;
import com.lxl.ggkt.vod.service.SubjectService;
import io.swagger.annotations.ApiOperation;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.List;

/**
 * <p>
 * 课程科目 前端控制器
 * </p>
 *
 * @author lxl
 * @since 2022-07-19
 */
@RestController
@RequestMapping("/admin/vod/subject")
//@CrossOrigin
public class SubjectController {

    @Autowired
    private SubjectService subjectService;

    @ApiOperation("课程分类列表")
    @GetMapping("getChildSubject/{id}")
    public Result getChildSubject(@PathVariable Long id){
        List<Subject> list = subjectService.selectSubjectList(id);
        return Result.ok(list);
    }

    //课程分类导出
    @ApiOperation("课程分类导出")
    @GetMapping("exportData")
    public void exportData(HttpServletResponse response){
        subjectService.exportData(response);
    }

    //课程分类导入
    @ApiOperation("课程分类导入")
    @PostMapping("importData")
    public Result importData(MultipartFile file){
        subjectService.importData(file);
        return Result.ok(null);
    }
}

数据文档的导入和导出使用EasyExcel进行操作：

首先为了清楚展示导入和导出的数据，本项目封装了SubjectEeVo类：

package com.lxl.ggkt.vo.vod;

import com.alibaba.excel.annotation.ExcelProperty;
import lombok.Data;

/**
 * <p>
 * Dict
 * </p>
 *
 * @author lxl
 */
@Data
public class SubjectEeVo {

	@ExcelProperty(value = "id" ,index = 0)
	private Long id;

	@ExcelProperty(value = "课程分类名称" ,index = 1)
	private String title;

	@ExcelProperty(value = "上级id" ,index = 2)
	private Long parentId;

	@ExcelProperty(value = "排序" ,index = 3)
	private Integer sort;

}

编写service实现类（显示课程列表，导入数据，导出数据，判断是否为父子节点）：

package com.lxl.ggkt.vod.service.impl;


import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.lxl.ggkt.exception.GgktException;
import com.lxl.ggkt.model.vod.Subject;
import com.lxl.ggkt.vo.vod.SubjectEeVo;
import com.lxl.ggkt.vod.listener.SubjectListener;
import com.lxl.ggkt.vod.mapper.SubjectMapper;
import com.lxl.ggkt.vod.service.SubjectService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import com.alibaba.excel.EasyExcel;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.net.URLEncoder;
import java.util.ArrayList;
import java.util.List;

/**
 * <p>
 * 课程科目 服务实现类
 * </p>
 *
 * @author atguigu
 * @since 2022-07-19
 */
@Service
public class SubjectServiceImpl extends ServiceImpl<SubjectMapper, Subject> implements SubjectService {

    @Autowired
    private SubjectListener subjectListener;

    @Override
    public List<Subject> selectSubjectList(Long id) {

        QueryWrapper<Subject> wrapper = new QueryWrapper<>();
        wrapper.eq("parent_id",id);
        List<Subject> subjectList = baseMapper.selectList(wrapper);

        for (Subject subject:subjectList){
            Long subjectId = subject.getId();
            boolean isChild = this.isChildren(subjectId);

            subject.setHasChildren(isChild);
        }
        return subjectList;
    }

    @Override
    public void exportData(HttpServletResponse response) {

        try{
            response.setContentType("application/vnd.ms-excel");
            response.setCharacterEncoding("utf-8");
            // 这里URLEncoder.encode可以防止中文乱码 当然和easyexcel没有关系
            String fileName = URLEncoder.encode("课程分类", "UTF-8");
            response.setHeader("Content-disposition", "attachment;filename="+ fileName + ".xlsx");

            List<Subject> subjectList = baseMapper.selectList(null);

            List<SubjectEeVo> subjectEeVoList = new ArrayList<>();
            for(Subject subject : subjectList) {
                SubjectEeVo subjectEeVo = new SubjectEeVo();
//                subjectEeVo.setId(subject.getId());
//                subjectEeVo.setParentId(subject.getParentId());

                BeanUtils.copyProperties(subject,subjectEeVo);
                subjectEeVoList.add(subjectEeVo);
            }

            EasyExcel.write(response.getOutputStream(), SubjectEeVo.class)
                    .sheet("课程分类").doWrite(subjectEeVoList);
        }catch (Exception e){
            throw new GgktException(20001,"导出失败");
        }



    }

    @Override
    public void importData(MultipartFile file) {
        try {
            EasyExcel.read(file.getInputStream(),SubjectEeVo.class,
                    subjectListener).sheet().doRead();
        } catch (IOException e) {
            throw new GgktException(20001,"导入失败");
        }
    }

    private boolean isChildren(Long subjectId) {

        QueryWrapper<Subject> wrapper = new QueryWrapper<>();
        wrapper.eq("parent_id",subjectId);
        Integer count = baseMapper.selectCount(wrapper);
        return count > 0;
    }
}

上述代码涉及到了读取监听器，它主要的作用是一行一行读取数据，调用方法插入数据，同时添加数据到数据库中：

package com.lxl.excel;

import com.alibaba.excel.context.AnalysisContext;
import com.alibaba.excel.event.AnalysisEventListener;

import java.util.Map;

@Component
public class SubjectListener extends AnalysisEventListener<SubjectEeVo> {
    @Autowired
    private SubjectMapper dictMapper;
    //一行一行读取
    @Override
    public void invoke(SubjectEeVo subjectEeVo, AnalysisContext analysisContext) {
        //调用方法添加数据库
        Subject subject = new Subject();
        BeanUtils.copyProperties(subjectEeVo,subject);
        dictMapper.insert(subject);
    }
    @Override
    public void doAfterAllAnalysed(AnalysisContext analysisContext) {
    }
}

最后查看对应的controller接口，导入，导出controller直接调用SubjectServiceImp接口即可。

package com.lxl.ggkt.vod.controller;


import com.lxl.ggkt.model.vod.Subject;
import com.lxl.ggkt.result.Result;
import com.lxl.ggkt.vod.service.SubjectService;
import io.swagger.annotations.ApiOperation;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.List;

/**
 * <p>
 * 课程科目 前端控制器
 * </p>
 *
 * @author lxl
 * @since 2022-07-19
 */
@RestController
@RequestMapping("/admin/vod/subject")
//@CrossOrigin
public class SubjectController {

    @Autowired
    private SubjectService subjectService;

    @ApiOperation("课程分类列表")
    @GetMapping("getChildSubject/{id}")
    public Result getChildSubject(@PathVariable Long id){
        List<Subject> list = subjectService.selectSubjectList(id);
        return Result.ok(list);
    }

    //课程分类导出
    @ApiOperation("课程分类导出")
    @GetMapping("exportData")
    public void exportData(HttpServletResponse response){
        subjectService.exportData(response);
    }

    //课程分类导入
    @ApiOperation("课程分类导入")
    @PostMapping("importData")
    public Result importData(MultipartFile file){
        subjectService.importData(file);
        return Result.ok(null);
    }
}