MultipartFormParser

A JVM library for parsing a multipart/form-data encoded stream.

Getting Started

Installation

I don't know, build the lib and use it?

Example usage

Given the body (InputStream) and boundary (from the ContentHeader) you create a StreamingMultipartFormParts object. That is an Iterator over StreamingParts. You can use this Iterator if you want to stream bytes directly from the form - for example if you think you are going to get very large files and want to send them directly to S3 or something.

Alternatively you can convert the Iterator into Parts using the MultipartFormMap.formMap. This is a Map of FieldNames to Parts. To create these Parts the entire stream has to be parsed and the contents of each Part stored in memory or on disk (the writeToDiskThreshold determines when to use memory and when to write to disk)

public class Example {
    public void example() {
        
        int maxStreamLength = 100_000; // maximum length of the stream, will throw exception if this is exceeded
        int writeToDiskThreshold = 1024; // maximum length of in memory object - if part is bigger then write to disk
        File temporaryFileDirectory = null; // use default temporary file directory
        String contentType = "multipart/form-data; boundary=------WebKitFormBoundary6LmirFeqsyCQRtbj"; // content type from HTTP header
        
        // you are responsible for closing the body InputStream
        try(InputStream body = new FileInputStream("examples/safari-example.multipart")) {
        
            byte[] boundary = contentType.substring(contentType.indexOf("boundary=") + "boundary=".length()).getBytes(ISO_8859_1);
            Iterable<StreamingPart> streamingParts = StreamingMultipartFormParts.parse(
                boundary, body, ISO_8859_1, maxStreamLength);
        
            try (Parts parts = MultipartFormMap.formMap(streamingParts, ISO_8859_1, writeToDiskThreshold, temporaryFileDirectory)) {
                Map<String, List<Part>> partMap = parts.partMap;
        
                Part articleType = partMap.get("articleType").get(0);
                System.out.println(articleType.fieldName); // "articleType"
                System.out.println(articleType.headers); // {Content-Disposition=form-data; name="articleType"}
                System.out.println(articleType.length); // 8 bytes
                System.out.println(articleType.isInMemory()); // true
                System.out.println(articleType.getString()); // "obituary"
        
                Part simple7bit = partMap.get("uploadManuscript").get(0);
                System.out.println(simple7bit.fieldName); // "uploadManuscript"
                System.out.println(simple7bit.fileName); // "simple7bit.txt"
                System.out.println(simple7bit.headers); // {Content-Disposition => form-data; name="uploadManuscript"; filename="simple7bit.txt"
                                                        // Content-Type => text/plain}
                System.out.println(simple7bit.length); // 8221 bytes
                System.out.println(simple7bit.isInMemory()); // false
                simple7bit.getNewInputStream(); // stream of the contents of the file
            } catch (IOException e) {
                // parsing can go wrong... handle it here
            }
            
        } catch (IOException e) {
            // general stream exceptions
        }
        
    }
}

I've done limited testing parsing forms with files, big and small and multiple, POSTed by Safari, Chrome, Firefox on Mac. Should probably test others at some point 😁.

Enjoy!

Development

Should be completely self contained. Tell me if it isn't

Running the tests

./gradlew clean test

Deployment

Just add the jar to your project. I guess I'll get a Maven thing set up at some point.

Built With

./gradlew clean test

This will create a jar

build/libs/multipart-form-parser-1.0.jar

Contributing

Contact me, Tiest Vilee, and ask.

Authors

• Tiest Vilee - Initial work - TiestVilee

See also the list of contributors who participated in this project.

License

This project is licensed under the Apache 2.0 License - see the LICENSE file for details

Acknowledgments

• Ripped off from the apache commons fileupload library