获取oss的pdf文件，返回文件输入流

需要：oss上存储生成的pdf文件，通过存储的key，返回对应的PDF文件输入流

实现： 后端Java提供获取pdf文件的输入流，前端vue将文件流另存为PDF文件

接口代码实现：

import java.io.BufferedInputStream;import java.io.InputStream;import java.util.Objects;import javax.servlet.ServletOutputStream;import javax.servlet.http.HttpServletResponse;import org.apache.commons.lang.StringUtils;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import com.aliyun.oss.model.OSSObject;import com.sisensing.cgm.common.core.utils.ErrUtil;import com.sisensing.cgm.system.domain.dto.ReportQueryDTO;import com.sisensing.cgm.system.service.ICgmDownloadService;import cn.hutool.core.io.IoUtil;import org.springframework.stereotype.Service;......private static final Logger LOGGER = LoggerFactory.getLogger(CgmDownloadServiceServiceImpl.class);    @Override    public void getReportFileStream(ReportQueryDTO reportQueryDTO, HttpServletResponse response) {        // 报告尚未生成pdf报告        ErrUtil.throwIfTrue(StringUtils.isEmpty(reportQueryDTO.getPdfKey()), REPORT_HAS_NOT_PDF,            String.format("pdfKey不容许为空"));        OSSObject ossObject = this.getServiceFactory().getOssService().downloadOssFile(reportQueryDTO.getPdfKey());        ServletOutputStream out = null;        if (Objects.nonNull(ossObject)) {            InputStream inputStream = ossObject.getObjectContent();            BufferedInputStream bis = new BufferedInputStream(inputStream);            int buffer = 1024 * 10;            byte[] data = new byte[buffer];            try {                response.setContentType("application/pdf");                // 文件名能够任意指定                long timeId = System.currentTimeMillis();                response.setHeader("Content-Disposition", "attachment;fileName=" + timeId + ".pdf");                int read;                out = response.getOutputStream();                while ((read = bis.read(data)) != -1) {                    out.write(data, 0, read);                }                out.flush();            } catch (Exception ex) {                IoUtil.close(out);                LOGGER.error("下载PDF报告失败", ex);                ErrUtil.throwNow(GET_REPORT_STREAM_FAIL, String.format("pdfKey为[%s]", reportQueryDTO.getPdfKey()));            } finally {                IoUtil.close(ossObject);            }        }    }        ......     @Autowired    private OSSClient ossClient;    @Autowired    private OSSProperties ossProperties;        /**     * 下载oss存储的文件对象     *     * @param key     * @return     */    public OSSObject downloadOssFile(String key) {        return ossClient.getObject(ossProperties.getBucketName(), key);    }

ps: 因为前端页面申请的形式是POST，若应用以下的形式将文件输入流保留

/**下载操作 */    handleDownload(row) {      if (row.pdfKey) {//已生成pdf          const param = { pdfKey : row.pdfKey};        getReportStream(param).then(res => {          if(!res) return          let url = window.URL.createObjectURL(new Blob([res]), { type: 'application/pdf' })          let link = document.createElement('a')          link.style.display = 'none'          link.href = url          link.setAttribute('download', `xxxx报告.pdf`)          document.body.appendChild(link)          link.click()          document.body.removeChild(link)          URL.revokeObjectURL(link.href) //开释URL对象        })      } else {        this.$message('报告正在生成中请稍后')      }    }//获取报告文件输入流export function getReportStream(data) {  return request({    url: `xxx/xxx/pdf/stream`,    method: 'post',    data: data,    responseType: 'blob',  })}

实现成果截图：

① blob返回的文件输入流，console打印

② swagger接口申请返回后果

③ 下载的前端入口

④ 下载胜利的pdf文件，在浏览器的左下角显示对应的文件