RestPack Java实现Html转PDF文件

最近公司需要将前端一个图表统计导出为pdf。前端导出显示的pdf还是可以的，但是将会导致页面不可用与卡死状态。所以由后端寻找解决方案。

以下为解决方案调研

https://www.cnblogs.com/IT-study/p/13706690.html

由于自己开发一个公共的导出pdf功能比较费时费力，而且导出过程中也遇到了各种样式问题。考虑再三决定使用第三方导出来解决这个问题。

好处：接入简单给个H5url即可，无需要考虑导出中遇到的写出的样式与排版问题

坏处：无法做到完全自定义。拿restPack举例子 ，导出长图无法自定义宽度，目前导出有1280px宽度，业务需要手机预览宽度只要 A6纸的规格即可。也可能可以通过js、css参数去解决，我没找到对应的方法。

官网：https://restpack.io/

解决思路

1.将一个可访问的H5URL转换为Pdf文件

2.将Pdf文件写到页面

H5URL转换为Pdf文件

@Component
public class H5UrlExportPdf {


    @Value("${restpack.token}")
    private String token = "HA5jLSVtSnjl3fmlhPgTg7rPRE4OnywDvh1CrbanXmpBvNqA";


    /**
     * https://restpack.io/html2pdf/docs
     */
    public ReturnRestPackPdf exportPdf(RestPackPdfParameters restpackPdfParameters) throws IOException {


        ReturnRestPackPdf returnRestPackPdf;

        //请求URL
        String reqUrl = "https://restpack.io/api/html2pdf/v6/convert";
        StringBuilder stringBuilder = new StringBuilder();

        //地址需要encode
        String firstP = "url";
        stringBuilder.append(firstP).append("=").append(restpackPdfParameters.getUrl());

        Map<String, String> describe = BeanHelper.describe(restpackPdfParameters);
        describe.forEach((name, val) -> {

            if (!firstP.equalsIgnoreCase(name)) {
                stringBuilder.append("&").append(name).append("=").append(val);
            }
        });

        System.out.println(stringBuilder.toString());

        byte[] postData = stringBuilder.toString().getBytes(StandardCharsets.UTF_8);
        HttpURLConnection con = null;

        try {

            URL myUrl = new URL(reqUrl);
            con = (HttpURLConnection) myUrl.openConnection();

            con.setDoOutput(true);
            con.setRequestMethod("POST");
            con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
            con.setRequestProperty("x-access-token", token);

            try (DataOutputStream wr = new DataOutputStream(con.getOutputStream())) {
                wr.write(postData);
            }

            StringBuilder content;

            try (BufferedReader in = new BufferedReader(
                    new InputStreamReader(con.getInputStream()))) {

                String line;
                content = new StringBuilder();

                while ((line = in.readLine()) != null) {
                    content.append(line);
                    content.append(System.lineSeparator());
                }
            }

            returnRestPackPdf = JSONObject.parseObject(content.toString(), ReturnRestPackPdf.class);

        } finally {
            if (con != null) {
                con.disconnect();
            }
        }

        return returnRestPackPdf;
    }


}

H5URL导出文档入参

@Data
public class RestPackPdfParameters implements Serializable{

    private static final long serialVersionUID = 1L;


    /**
     * 需要导出文档H5URL
     * The URL of web page, including the protocol that you want to capture.
     * Example: http://example.com
     */
    private String url;


    /**
     * Return a JSON response with the resulting image's URL instead of the image itself.
     * Default: false
     */
    private Boolean json = true;


    /**
     * Page size for created document
     *
     * Default: Full
     * Pattern: A0 | A1 | A2 | A3 | A4 | A5 | A6 | Legal | Letter | Tabloid | Ledger | Full
     *
     * Legal：width 816 多张图片阶段
     * Letter：width 816 多张图片阶段
     * Tabloid：width 1056 多张图片阶段
     * Ledger：width 1632 多张图片阶段
     * Full：width 1280 一张图片
     */
    private String pdf_page="Full";

    public RestPackPdfParameters() {
    }

    public RestPackPdfParameters(String url) {
        this.url = url;
    }
}

H5URL导出文档返回参数

@Data
public class ReturnRestPackPdf implements Serializable{

    private static final long serialVersionUID = 1L;


    private Boolean cached;
    private String content_type;
    /** pdf文件类型地址 */
    private String file;
    private Integer height;
    private Integer width;
    /** pdf图片类型地址 */
    private String image;
    private String length;
    private String remote_status;
    private String run_time;
    private String url;

}

将文件写到页面

    private void downFileHtml(String name, @RequestParam(value = "fileUrl", required = false) String fileUrl, HttpServletResponse response, Boolean useName) {
        BufferedInputStream bis = null;
        BufferedOutputStream bos = null;
        OutputStream output = null;
        try {
            log.info("downLoadFileStart:" + fileUrl);
            response.setContentType("application/octet-stream; charset=UTF-8");
            if (useName) {

            } else {
                String ext = fileUrl.substring(fileUrl.lastIndexOf("."));
                name = name + ext;
                name = URLDecoder.decode(name, "UTF-8");
            }

            response.setHeader("Content-Disposition", "attachment;fileName="" + new String(name.getBytes("GBK"), "ISO8859-1") + """);

            URL url = new URL(fileUrl);
            bis = new BufferedInputStream(url.openStream());
            output = response.getOutputStream();
            bos = new BufferedOutputStream(output);
            log.info("downLoadFileCopyStream:" + fileUrl);
            byte[] buff = new byte[2048];
            int bytesRead;
            while (-1 != (bytesRead = bis.read(buff, 0, buff.length))) {
                log.info("downLoadFileCopyStreamDetail:" + bytesRead);
                bos.write(buff, 0, bytesRead);
            }
            log.info("downLoadFileEnd:" + fileUrl);
        } catch (Exception e) {
            log.error("downLoadFileError:" + fileUrl + ":error:" + e.getMessage());
            e.printStackTrace();
        } finally {
            try {
                if (bos != null) {
                    bos.flush();
                    bos.close();
                }
                if (bis != null) {
                    bis.close();
                }
                if (output != null) {
                    output.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

使用事项

1.url 为转换pdf的页面地址，改地址必须能直接访问(无登录功能)

2.pdf_page 有几个页面规格 A0 | A1 | A2 | A3 | A4 | A5 | A6 | Legal | Letter | Tabloid | Ledger | Full 。Full可导出一张长图，但是宽度不可定。其他的规格与A4类似，导出的是多张图片。

3.pdf_width 、pdf_height 可自定义页面规格。一旦pdf_page设置，pdf_width pdf_height必须为空。

4.一旦付费成功 css、js 可进行调节生成pdf文件产生的样式问题。

5.我们需要导出一整张图片，但是一整张图的宽度不可自定义。导出的宽度为1280px,手机上显示只需要800px。目前这个问题还不知道怎么解决