zhangwei5095 / htmltopdf-java

An HTML to PDF conversion library written in Java, based on wkhtmltopdf.

Overview

This project is based on wkhtmltopdf, which converts HTML documents to PDF. Access to wkhtmltopdf is performed via JNA, exposed through a Java-friendly layer.

Get it

Gradle:

compile 'io.woo:htmltopdf:1.0.8'

Maven:

<dependency>
  <groupId>io.woo</groupId>
  <artifactId>htmltopdf</artifactId>
  <version>1.0.8</version>
  <scope>compile</scope>
</dependency>

Getting started

The following examples should be sufficient to get you started, however there are many more options discoverable by looking into the methods of HtmlToPdf and HtmlToPdfObject.

Saving HTML as a PDF file

boolean success = HtmlToPdf.create()
    .object(HtmlToPdfObject.forHtml("<p><em>Apples</em>, not oranges</p>"))
    .convert("/path/to/file.pdf");

Saving a webpage from URL as a PDF file

boolean success = HtmlToPdf.create()
    .object(HtmlToPdfObject.forUrl("https://github.com/wooio/htmltopdf-java"))
    .convert("/path/to/file.pdf");

Saving multiple objects as a PDF file

boolean success = HtmlToPdf.create()
    .object(HtmlToPdfObject.forUrl("https://github.com/wooio/htmltopdf-java"))
    .object(HtmlToPdfObject.forHtml("<p>This is the second object...</p>"))
    // ...
    .convert("/path/to/file.pdf");

Converting to InputStream (instead of saving as file)

Converting to an InputStream would be useful if you intend on returning the resulting PDF document as an HTTP response or adding it as an email attachment

HtmlToPdf htmlToPdf = HtmlToPdf.create()
    // ...
    .object(HtmlToPdfObject.forUrl("https://github.com/wooio/htmltopdf-java"));

try (InputStream in = htmlToPdf.convert()) {
    // "in" has PDF bytes loaded
} catch (HtmlToPdfException e) {
    // HtmlToPdfException is a RuntimeException, thus you are not required to
    // catch it in this scope. It is thrown when the conversion fails
    // for any reason.
}

Concurrency limitations

While the library is thread-safe, it unfortunately cannot perform conversions concurrently. Because wkhtmltopdf uses Qt behind the scenes to render webpages, there is a single thread which performs such rendering across a single process. Therefore, at this point, it is only possible to perform one conversion at the same time per process.

Troubleshooting

Missing native dependencies

If you get the following exception:

java.lang.UnsatisfiedLinkError: Unable to load library '/tmp/io.woo.htmltopdf/wkhtmltox/0.12.5/libwkhtmltox.so': Native library (tmp/io.woo.htmltopdf/wkhtmltox/0.12.5/libwkhtmltox.so) not found in resource path

Then that likely means that one of the native dependencies of wkhtmltopdf is not met. It might be worth checking that the following packages are installed:

• libc6 (or glibc)
• libx11
• libxext
• libxrender
• libstdc++
• libssl1.0
• freetype
• fontconfig