Java后端返回PDF预览给前端

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Java后端返回PDF预览给前端

2024-06-02 13:39| 来源: 网络整理| 查看: 265

前端要预览服务器PDF 可直接将要blob流返回给前端即可用浏览器自带pdf预览功能打开，现有两种方式

方式1 返回blob流给前端代码如下

@PostMapping(value = "/preview") @ResponseBody public void showPdf(HttpServletResponse response) { try { File file = new File("filePath"); OutputStream out = null; try (BufferedInputStream br = new BufferedInputStream(new FileInputStream(file)); ) { byte[] bs = new byte[1024]; int len; response.reset(); // 非常重要 URL u = new URL("file:///" + "filePath"); String contentType = u.openConnection().getContentType(); response.setContentType(contentType); response.setHeader("Content-Disposition", "inline;filename=" + "preview.pdf"); out = response.getOutputStream(); while ((len = br.read(bs)) > 0) { out.write(bs, 0, len); } out.flush(); out.close(); } } catch (Exception e) { e.printStackTrace(); } }

此时前端解析可直接拿返回的文件流例子如下

let blob = this.response; const binaryData = []; binaryData.push(blob); const url = window.URL.createObjectURL(new Blob(binaryData, { type: 'application/pdf' })); window.open(url);

但有的时候不想返回文件流可把文件返回为base64 （注意 base64可能超长）此时代码修改如下

File file = new File("filePath"); OutputStream out = null; try (BufferedInputStream br = new BufferedInputStream(new FileInputStream(file)); ByteArrayOutputStream outStream = new ByteArrayOutputStream(); ) { int len; URL u = new URL("file:///" + "filePath"); String contentType = u.openConnection().getContentType(); byte[] buffer = new byte[1024]; //每次读取的字符串长度，如果为-1，代表全部读取完毕 //使用输入流从buffer里把数据读取出来 while ((len = br.read(buffer)) != -1) { //用输出流往buffer里写入数据，中间参数代表从哪个位置开始读，len代表读取的长度 outStream.write(buffer, 0, len); } // 对字节数组Base64编码 Base64Encoder base64 = new Base64Encoder(); String base64Str = replaceEnter(base64.encode(outStream.toByteArray())); } } catch (Exception e) { }

前端修改如下

let base64 = resBase64.data.base64; base64 = base64.replace(/[\n\r]/g, '') const raw = window.atob(base64) const rawLength = raw.length const uInt8Array = new Uint8Array(rawLength) for (let i = 0; i < rawLength; ++i) { uInt8Array[i] = raw.charCodeAt(i) } const url = window.URL.createObjectURL(new Blob([uInt8Array], { type: resBase64.data.contentType })); window.open(url);

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Java后端返回PDF预览给前端

Java后端返回PDF预览给前端

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