解决java POI导入Excel超时问题

由于要导入大量数据，后台会耗费很长时间，导致超时。

本项目前端request.js中设定的超时时间为150s.

const service = axios.create({
    baseURL: baseUrl,
    withCredentials: true,
    timeout: 150000
});

我们的做法是：

前端导入Excel向后台发出请求时，后台立即返回信息“后台正在导入，请稍等！”，向redis中存入键isFinished的值为字符串“0”，并且开启一个线程来完成插入大量数据到数据库的工作，当插入完成则将redis中isFinished的值改为字符串“1”。前端收到“后台正在输入，请稍等！”后，此时导入按钮处于禁用状态并且处于加载状态。通过window.setInterval定时轮询，每隔30秒去后台查询ifFinished值，如果为字符串“1”表示上传完毕，此时在弹框“上传完毕！”，此时导入按钮禁用状态和加载状态都取消,并且刷新列表。

前端代码：

<div style="margin-bottom: 10px">
        <el-form :inline="true">
          <el-form-item label="">
            <el-button type="success" icon="el-icon-download" @click="downloadTemplate">下载模板</el-button>
            <el-button :loading="importLoading" type="primary" icon="el-icon-upload" @click="handleImport">导入
            </el-button>
            <el-upload ref="importUpload" :auto-upload="false" :show-file-list="false" :on-change="handleUploadChange"
              :disabled="importDisabled" style="display: inline" action="#" class="upload-demo">
              <el-button id="uploadButton" style="display: none" slot="trigger" :loading="importLoading" size="small"
                type="primary" icon="el-icon-upload">导入</el-button>
            </el-upload>
          </el-form-item>
          <el-form-item label="">
            <el-button type="warning" icon="el-icon-lightning" @click="exportExcel">导出</el-button>
          </el-form-item>
        </el-form>
      </div>

handleUploadChange(file) {
  if (file.name.lastIndexOf('.') < 0) {
    this.$message.error('上传文件只能是xls、xlsx格式!')
    return
  }
  const testMsg = file.name.substring(file.name.lastIndexOf('.') + 1).toLowerCase()
  const extensionXLS = testMsg == 'xls'
  const extensionXLSX = testMsg == 'xlsx'
  if (!extensionXLS && !extensionXLSX) {
    this.$message.error('上传文件只能是xls、xlsx格式!')
    return
  }
  const isLt2M = file.size / 1024 / 1024 < 2
  if (!isLt2M) {
    this.$message.error('上传文件不能超过 2MB!')
    return
  }
  this.importLoading = true
  this.importDisabled = true
  const data = new FormData()
  data.append('file', file.raw)
  medicineListApi.importExcel(data).then(response => {
    if (response.status == true) {
      this.open2(response.msg)
      this.getList()
    } else {
      this.open2(response.msg)
      this.importLoading = false
      this.importDisabled = false
    }
    window.setInterval(() => {
      setTimeout(this.getStatus(), 0)
    }, 30*1000)
  }).catch(() => {
    this.open2('抱歉，导入失败')
    this.importLoading = false
    this.importDisabled = false
  })

},
open2(str) {
  this.$notify({
    title: '提示',
    message: str,
    duration: 0
  })
},

// 请求后台获取是否导入完成的状态
getStatus(){
  medicineListApi.getStatus().then(response => {
    if (response.data == "1") {
      this.open2("上传完毕！")
      this.importLoading = false
      this.importDisabled = false
      this.getList()
    }
  })
}

项目中我们经常需要实现轮询-每隔几秒请求一次接口刷新数据，一般都会使用setInterval，但要注意单纯使用它会导致页面卡死，解释：setInterval不会清除定时器队列，每重复执行1次都会导致定时器叠加，最终卡死你的网页。但是setTimeout是自带清除定时器的

解决办法：

window.setInterval(() => {
  setTimeout(fun, 0)
}, 30000)

setTimeout() 方法用于在指定的毫秒数后调用函数或计算表达式。 如果你只想重复执行可以使用 setInterval() 方法。setTimeout()只执行一次，而setInterval可以多次调用。

medicineList.js代码：

import request from "./request";

const baseUrl = "/medicineList"
export const medicineListApi = {
  /**
   * 导入
   * @param data
   */
  importExcel(data) {
    return request({
      url: baseUrl + '/import',
      method: 'post',
      data: data,
      headers: {
        'Content-Type': 'multipart/form-data'
      }
    })
  },
  getStatus() {
    return request({
      url: baseUrl + "/getStatus",
      method: "GET"
    });
  },
};

后台代码：

controller：

@RestController
@RequestMapping("/medicineList")
@Slf4j
public class MedicineListController extends BaseController {

    @Autowired
    private MedicineListService medicineListService;

    /**
     * 导入药品信息
     *
     * @param file
     * @return
     * @throws Exception
     */
    @PostMapping("/import")
    public JSONObject importNodeInfo(MultipartFile file) throws Exception {
        return medicineListService.importNodeInfo(file.getInputStream());
    }

    @GetMapping("/getStatus")
    public JSONObject getStatus() {
        return medicineListService.getStatus();
    }
}

service接口：

public interface MedicineListService extends IService<DrugData> {
    JSONObject importNodeInfo(InputStream inputStream) throws Exception;

    JSONObject getStatus();
}

service实现类：

@Service
public class MedicineListServiceImpl extends ServiceImpl<MedicineListMapper,DrugData> implements MedicineListService {

    @Resource
    private MedicineListMapper medicineListMapper;

    private static Logger logger = LoggerFactory.getLogger(MedicineListService.class);
    @Autowired
    private StringRedisTemplate redisTemplate;

    public JSONObject importNodeInfo(InputStream in) throws Exception {
        redisTemplate.opsForValue().set("isFinished","0",60*60l,TimeUnit.SECONDS);
        JSONObject json = new JSONObject();
        json.put("msg", "后台正在导入，请稍等！");
        json.put("status", true);
        new Thread() {
            @Override
            public void run() {
                try {
                    //   根据类型进行分流导入
                    String str0 = "";
                    String str = "";
                    String fstr = "";
                    int operCount = 0;
                    XSSFWorkbook workbook = new XSSFWorkbook(in);
                    XSSFSheet sheet = workbook.getSheetAt(0);
                    int totalColumnNum = sheet.getRow(0).getLastCellNum();
                    logger.info("导入代码信息excel文件的总列数:" + totalColumnNum);
                    System.out.println(totalColumnNum);
                    int lastRowNum = sheet.getLastRowNum();

                    logger.info("导入节点信息excel文件的总行数:" + lastRowNum);
                    System.out.println(sheet.getLastRowNum());
                    for (int num = 0; num <= lastRowNum; num++) {
                        XSSFRow row = sheet.getRow(num);
                        if(row == null) {
                            str0 = "存在空数据行，行号：" + (num + 1) + "，导入失败！";
                            break;
                        }
                        int hcount = num + 1;
                        if (num == 0) {
                            if (null != String.valueOf(row.getCell(0)) && String.valueOf(row.getCell(0)).equals("药品编码")) {
                                continue;
                            } else {

                                json.put("msg", "导入的模板名称出错，请确认");
                                json.put("status", false);
                                json.put("data", operCount);

                            }
                        }
                        DrugData drugData = new DrugData();
                        String drugNo = String.valueOf(row.getCell(0));
                        if(StringUtils.isNotBlank(drugNo) && !"null".equalsIgnoreCase(drugNo)) {
                            drugData.setDrugno(drugNo);// 药品编码
                        }
                        String drugName = String.valueOf(row.getCell(1));
                        if(StringUtils.isNotBlank(drugName) && !"null".equalsIgnoreCase(drugName)) {
                            drugData.setDrugname(drugName);//药品名称
                        }
                        String indiction = String.valueOf(row.getCell(2));
                        if(StringUtils.isNotBlank(indiction) && !"null".equalsIgnoreCase(indiction)) {
                            drugData.setIndiction(indiction); //适应症
                        }

                        try {
                            QueryWrapper<DrugData> wrapper = new QueryWrapper<>();
                            if(StringUtils.isNotBlank(drugData.getDrugno())){
                                wrapper.eq("drugno",drugData.getDrugno());
                            }
                            List<DrugData> drugDataList = medicineListMapper.selectList(wrapper);

                            if (null != drugDataList && drugDataList.size() > 0) {
                                drugData.setId(drugDataList.get(0).getId());
                                medicineListMapper.updateById(drugData);
                            } else {
                                medicineListMapper.insert(drugData);
                            }
                        } catch (Exception e) {
                            logger.error(e.getMessage());
                            str = str + "第【" + hcount + "】行，";
                            continue;
                        }
                        operCount++;
                    }
                    if (StringUtils.isNotBlank(str)) {
                        str = "其中-->" + str + "导入失败！";
                    }

                    if (StringUtils.isNotBlank(fstr)) {
                        fstr = "==投量-->" + fstr + "附表导入失败！";
                    }
                    redisTemplate.opsForValue().set("isFinished","1");

                    json.put("msg", "操作成功" + str0 + str + fstr);
                    json.put("status", true);
                    json.put("data", operCount);

                } catch (Exception e) {
                    logger.error(e.getMessage());
                } finally {
                    try {
                        in.close();
                    } catch (IOException e) {
                        logger.error(e.getMessage());
                    }
                }
            }
        }.start();
        return json;
    }
    @Override
    public JSONObject getStatus() {
        String isFinished = redisTemplate.opsForValue().get("isFinished");
        JSONObject result = new JSONObject();
        if (StringUtils.isNotBlank(isFinished)) {
            result.put("msg", "获取成功");
            result.put("status", true);
            result.put("data",isFinished);
        } else {
            result.put("msg", "获取失败");
            result.put("status", false);
        }
        redisTemplate.delete("isFinished");
        return result;
    }
}

注意：导入Excel时，String.valueOf(row.getCell(0))获取的值出了要进行非空判断外，还要判断不为字符串null，再执行插入，否则Excel中未填写的单元格插入数据库会变成字符串null。