HTML到pdf的转换和下载

Question

我有一个用于简单测验的Angular Web应用程序，在最后一个测验的末尾，我将结果绑定到HTML模板中。 以前，我可以从此HTML模板使用PHP mpdf库生成pdf文件，现在在Spring Boot中构建业务逻辑和安全性时，我也想在Spring Boot中做到这一点。 我使用了飞碟，并且可以从资源文件夹中的HTML模板生成pdf文件。 问题是如何从前端获取此HTML文件并从中生成pdf文件，然后将最后一个文件下载到我的PC中？

@Service
public class PdfService {
    private static final String OUTPUT_FILE = "test.pdf";
    private static final String UTF_8 = "UTF-8";

    @Test
    public void generatePdf() throws Exception {


        // We set-up a Thymeleaf rendering engine. All Thymeleaf templates
        // are HTML-based files located under "src/test/resources". Beside
        // of the main HTML file, we also have partials like a footer.html or
        // a header. We can re-use those partials in different documents.
        ClassLoaderTemplateResolver templateResolver = new ClassLoaderTemplateResolver();
        templateResolver.setPrefix("/");
        templateResolver.setSuffix(".html");
        templateResolver.setTemplateMode(HTML);
        templateResolver.setCharacterEncoding(UTF_8);

        TemplateEngine templateEngine = new TemplateEngine();
        templateEngine.setTemplateResolver(templateResolver);

        // The data in our Thymeleaf templates is not hard-coded. Instead,
        // we use placeholders in our templates. We fill these placeholders
        // with actual data by passing in an object. In this example, we will
        // write a letter to "John Doe".
        //
        // Note that we could also read this data from a JSON file, a database
        // a web service or whatever.
        Data data = exampleDataForJohnDoe();

        Context context = new Context();
        context.setVariable("data", data);

        // Flying Saucer needs XHTML - not just normal HTML. To make our life
        // easy, we use JTidy to convert the rendered Thymeleaf template to
        // XHTML. Note that this might not work for very complicated HTML. But
        // it's good enough for a simple letter.
        String renderedHtmlContent = templateEngine.process("template", context);
        String xHtml = convertToXhtml(renderedHtmlContent);

        ITextRenderer renderer = new ITextRenderer();
        renderer.getFontResolver().addFont("Code39.ttf", IDENTITY_H, EMBEDDED);

        // FlyingSaucer has a working directory. If you run this test, the working directory
        // will be the root folder of your project. However, all files (HTML, CSS, etc.) are
        // located under "/src/test/resources". So we want to use this folder as the working
        // directory.
        String baseUrl = FileSystems
                .getDefault()
                .getPath("src", "test", "resources")
                .toUri()
                .toURL()
                .toString();
        renderer.setDocumentFromString(xHtml, baseUrl);
        renderer.layout();

        // And finally, we create the PDF:
        OutputStream outputStream = new FileOutputStream(OUTPUT_FILE);
        renderer.createPDF(outputStream);
        outputStream.close();
    }

    private Data exampleDataForJohnDoe() {
        Data data = new Data();
        data.setFirstname("John");
        data.setLastname("Doe");
        data.setStreet("Example Street 1");
        data.setZipCode("12345");
        data.setCity("Example City");
        return data;
    }

    static class Data {
        private String firstname;
        private String lastname;
        private String street;
        private String zipCode;
        private String city;

        public String getFirstname() {
            return firstname;
        }

        public void setFirstname(String firstname) {
            this.firstname = firstname;
        }

        public String getLastname() {
            return lastname;
        }

        public void setLastname(String lastname) {
            this.lastname = lastname;
        }

        public String getStreet() {
            return street;
        }

        public void setStreet(String street) {
            this.street = street;
        }

        public String getZipCode() {
            return zipCode;
        }

        public void setZipCode(String zipCode) {
            this.zipCode = zipCode;
        }

        public String getCity() {
            return city;
        }

        public void setCity(String city) {
            this.city = city;
        }
    }

    private String convertToXhtml(String html) throws UnsupportedEncodingException {
        Tidy tidy = new Tidy();
        tidy.setInputEncoding(UTF_8);
        tidy.setOutputEncoding(UTF_8);
        tidy.setXHTML(true);
        ByteArrayInputStream inputStream = new ByteArrayInputStream(html.getBytes(UTF_8));
        ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
        tidy.parseDOM(inputStream, outputStream);
        return outputStream.toString(UTF_8);
    }