I am using a document converter api called cloudconvert. They don't have an official java library, but a third party java option. I needed a little customization so I cloned the github project and added it to my project. I am sending cloudconvert a .epub file and getting a .pdf file in return. If I use the default settings it works without issue and properly converts my .epub to a .pdf. Here is the code that makes it happen.
Here is what triggers the conversion:
// Create service object
CloudConvertService service = new CloudConvertService("api-key");
// Create conversion process
ConvertProcess process = service.startProcess(convertFrom, convertTo);
// Perform conversion
//convertFromFile is a File object with a .epub extension
process.startConversion(convertFromFile);
// Wait for result
ProcessStatus status;
waitLoop:
while (true) {
status = process.getStatus();
switch (status.step) {
case FINISHED:
break waitLoop;
case ERROR:
throw new RuntimeException(status.message);
}
// Be gentle
Thread.sleep(200);
}
//Download result
service.download(status.output.url, convertToFile);
//lean up
process.delete();
startConversion() calls:
public void startConversion(File file) throws ParseException, FileNotFoundException, IOException {
if (!file.exists()) {
throw new FileNotFoundException("File not found: " + file);
}
startConversion(new FileDataBodyPart("file", file));
}
Which calls this to actually send the POST request using jersey:
private void startConversion(BodyPart bodyPart) {
if (args == null) {
throw new IllegalStateException("No conversion arguments set.");
}
MultiPart multipart = new FormDataMultiPart()
.field("input", "upload")
.field("outputformat", args.outputformat)
.bodyPart(bodyPart);
//root is a class level WebTarget object
root.request(MediaType.APPLICATION_JSON).post(Entity.entity(multipart, multipart.getMediaType()));
}
Up to this point everything is working. My problem is that the when the conversion happens the .pdf that returns has very small margins. cloudconvert provides a way to change those margins. You can send in an optional json param converteroptions and set the margins manually. I have tested this out using postman and it works without issue, I was able to get a properly formatted margin document. So know this is possible. Here is the POSTMAN info I used:
@POST : https://host123d1qo.cloudconvert.com/process/WDK9Yq0z1xso6ETgvpVQ
Headers: 'Content-Type' : 'application/json'
Body:
{
"input": "base64",
"file": "0AwAAIhMAAAAA", //base64 file string that is much longer than this
"outputformat": "pdf",
"converteroptions": {
"margin_bottom": 75,
"margin_top": 75,
"margin_right": 50,
"margin_left": 50
}
}
Here are my attempts at getting the POST request formatted properly, I'm just not very experienced with jersey and the couple of answers I did find on stackoverflow didn't work for me.
Attempt 1, I tried adding the json string as a Multipart.field. It didn't give me any errors and still returned a converted .pdf file, but the margins didn't get changed so I must not be sending it back right.
private void startConversion(BodyPart bodyPart) {
String jsonString = "{\"margin_bottom\":75,\"margin_top\":75,\"margin_right\":50,\"margin_left\":50}";
MultiPart multipart = new FormDataMultiPart()
.field("input", "upload")
.field("outputformat", args.outputformat)
.field("converteroptions", jsonString)
.bodyPart(bodyPart);
root.request(MediaType.APPLICATION_JSON).post(Entity.entity(multipart, multipart.getMediaType()));
}
Attempt 2, when I had it working in POSTMAN it was using the 'input' type as 'base64' so I tried changing it to that but it this time it doesn't return anything at all, no request errors, just a timeout error at the 5 minute mark.
//I pass in a File object rather than the bodypart object.
private void startConversion(File file) {
byte[] encoded1 = Base64.getEncoder().encode(FileUtils.readFileToByteArray(file));
String encoded64 = new String(encoded1, StandardCharsets.US_ASCII);
String jsonString = "{\"margin_bottom\":75,\"margin_top\":75,\"margin_right\":50,\"margin_left\":50}";
MultiPart multipart = new FormDataMultiPart()
.field("input", "base64")
.field("outputformat", args.outputformat)
.field("file", encoded64)
.field("converteroptions", jsonString);
root.request(MediaType.APPLICATION_JSON).post(Entity.entity(multipart, multipart.getMediaType()));
}
Attempt 3, after some googling on how to properly send jersey json post requests I changed the format. This time it returned a 400 bad request error.
private void startConversionPDF(File file) throws IOException {
byte[] encoded1 = Base64.getEncoder().encode(FileUtils.readFileToByteArray(file));
String encoded64 = new String(encoded1, StandardCharsets.US_ASCII);
String jsonString = "{\"input\":\"base64\",\"file\":\"" + encoded64 + "\",\"outputformat\":\"pdf\",\"converteroptions\":{\"margin_bottom\":75,\"margin_top\":75,\"margin_right\":50,\"margin_left\":50}}";
root.request(MediaType.APPLICATION_JSON).post(Entity.json(jsonString));
}
Attempt 4, Someone said you don't need to manually use a jsonString you should use serializable java beans. So I created the corresponding classes and made the request like shown below. Same 400 bad request error.
@XmlRootElement
public class PDFConvert implements Serializable {
private String input;
private String file;
private String outputformat;
private ConverterOptions converteroptions;
//with the a default constructor and getters/setters for all
}
@XmlRootElement
public class ConverterOptions implements Serializable {
private int margin_bottom;
private int margin_top;
private int margin_left;
private int margin_right;
//with the a default constructor and getters/setters for all
}
private void startConversionPDF(File file) throws IOException {
byte[] encoded1 = Base64.getEncoder().encode(FileUtils.readFileToByteArray(file));
String encoded64 = new String(encoded1, StandardCharsets.US_ASCII);
PDFConvert data = new PDFConvert();
data.setInput("base64");
data.setFile(encoded64);
data.setOutputformat("pdf");
ConverterOptions converteroptions = new ConverterOptions();
converteroptions.setMargin_top(75);
converteroptions.setMargin_bottom(75);
converteroptions.setMargin_left(50);
converteroptions.setMargin_right(50);
data.setConverteroptions(converteroptions);
root.request(MediaType.APPLICATION_JSON).post(Entity.json(data));
}
I know this is quite the wall of text, but I wanted to show all the different things I tried so that I wouldn't waste anyone's time. Thank you for any help or ideas you might have to make this work. I really want to make it work with jersey because I have several other conversions I do that work perfectly, they just don't need any converteroptions. Also I know its possible because it works when manually running the process through POSTMAN.
Cloudconvert api documentation for starting a conversion
Github repo with the recommended 3rd party java library I am using/modifying
I finally figured it out. Hours of trial and error. Here is the code that did it:
private void startConversionPDF(File file) throws IOException {
if (args == null) {
throw new IllegalStateException("No conversion arguments set.");
}
PDFConvert data = new PDFConvert();
data.setInput("upload");
data.setOutputformat("pdf");
ConverterOptions converteroptions = new ConverterOptions();
converteroptions.setMargin_top(60);
converteroptions.setMargin_bottom(60);
converteroptions.setMargin_left(30);
converteroptions.setMargin_right(30);
data.setConverteroptions(converteroptions);
MultiPart multipart = new FormDataMultiPart()
.bodyPart(new FormDataBodyPart("json", data, MediaType.APPLICATION_JSON_TYPE))
.bodyPart(new FileDataBodyPart("file", file));
root.request(MediaType.APPLICATION_JSON).post(Entity.entity(multipart, multipart.getMediaType()));
}