RESTEasy (WildFly – JAX-RS 2.1) file handling

Last Updated: February 26, 2020 | Published: April 21, 2019

In my latest blog post, I demonstrated a solution for up- and downloading files with Jersey (JAX-RS 2.1) on Payara. As WildFly does not rely on Jersey as the JAX-RS reference implementation and is using RESTEasy instead, I'll show you a quick example for file handling with RESTEasy on WildFly.

Setting up the backend using RESTEasy

For this blog post, I'm using a classic Java EE 8 Maven application with RESTEasy's multipart-provider as a provided and additional dependency (no need to package the library within the .war as WildFly already contains this lib):

<project xmlns="http://maven.apache.org/POM/4.0.0"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>de.rieckpil.blog</groupId>
  <artifactId>rest-easy-file-uploading-and-downloading</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>war</packaging>
  <dependencies>
    <dependency>
      <groupId>javax</groupId>
      <artifactId>javaee-api</artifactId>
      <version>8.0</version>
      <scope>provided</scope>
    </dependency>
    <dependency>
      <groupId>org.jboss.resteasy</groupId>
      <artifactId>resteasy-multipart-provider</artifactId>
      <version>3.6.3.Final</version>
      <scope>provided</scope>
    </dependency>
  </dependencies>
  <build>
    <finalName>rest-easy-file-uploading-and-downloading</finalName>
  </build>
  <properties>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
    <failOnMissingWebXml>false</failOnMissingWebXml>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
  </properties>
</project>

<project xmlns="http://maven.apache.org/POM/4.0.0"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

<groupId>de.rieckpil.blog</groupId>

<artifactId>rest-easy-file-uploading-and-downloading</artifactId>

<version>1.0-SNAPSHOT</version>

<groupId>javax</groupId>

<artifactId>javaee-api</artifactId>

<scope>provided</scope>

</dependency>

<groupId>org.jboss.resteasy</groupId>

<artifactId>resteasy-multipart-provider</artifactId>

<version>3.6.3.Final</version>

<scope>provided</scope>

</dependency>

</dependencies>

<build>

<finalName>rest-easy-file-uploading-and-downloading</finalName>

</build>

<maven.compiler.source>1.8</maven.compiler.source>

<maven.compiler.target>1.8</maven.compiler.target>

<failOnMissingWebXml>false</failOnMissingWebXml>

<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>

</properties>

</project>

The JAX-RS configuration is pretty straightforward:

@ApplicationPath("resources")
public class JAXRSConfiguration extends Application {

}

@ApplicationPath("resources")

public class JAXRSConfiguration extends Application {

}

Next, for storing the uploaded file, I'm using a simple JPA entity called FileUpload:

@Entity
public class FileUpload {

  @Id
  @GeneratedValue(strategy = GenerationType.IDENTITY)
  private Long id;

  private String fileName;

  private String contentType;

  @Lob
  private byte[] data;

       // constructors, getters & setters
}

@Entity

public class FileUpload {

@Id

@GeneratedValue(strategy = GenerationType.IDENTITY)

private Long id;

private String fileName;

private String contentType;

@Lob

private byte[] data;

// constructors, getters & setters

}

The file handling within the JAX-RS endpoint method is not as straightforward as with Jersey as you have to work with the MultipartFormDataInput interface and manually extract the filename and content-type:

@Path("files")
@Stateless
public class FileUploadResource {

  @PersistenceContext
  private EntityManager em;


  @POST
  @Consumes(MediaType.MULTIPART_FORM_DATA)
  public void uploadFile(MultipartFormDataInput incomingFile) throws IOException {

    InputPart inputPart = incomingFile.getFormDataMap().get("file").get(0);
    InputStream uploadedInputStream = inputPart.getBody(InputStream.class, null);

    ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
    byte[] buffer = new byte[1024];
    int len;

    while ((len = uploadedInputStream.read(buffer)) != -1) {
      byteArrayOutputStream.write(buffer, 0, len);
    }

    FileUpload upload = new FileUpload(
        getFileNameOfUploadedFile(inputPart.getHeaders().getFirst("Content-Disposition")),
        getContentTypeOfUploadedFile(inputPart.getHeaders().getFirst("Content-Type")),
        byteArrayOutputStream.toByteArray());

    em.persist(upload);
  }

}

@Path("files")

@Stateless

public class FileUploadResource {

@PersistenceContext

private EntityManager em;

@POST

@Consumes(MediaType.MULTIPART_FORM_DATA)

public void uploadFile(MultipartFormDataInput incomingFile) throws IOException {

InputPart inputPart = incomingFile.getFormDataMap().get("file").get(0);

InputStream uploadedInputStream = inputPart.getBody(InputStream.class, null);

ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();

byte[] buffer = new byte[1024];

int len;

while ((len = uploadedInputStream.read(buffer)) != -1) {

byteArrayOutputStream.write(buffer, 0, len);

}

FileUpload upload = new FileUpload(

getFileNameOfUploadedFile(inputPart.getHeaders().getFirst("Content-Disposition")),

getContentTypeOfUploadedFile(inputPart.getHeaders().getFirst("Content-Type")),

byteArrayOutputStream.toByteArray());

em.persist(upload);

}

RESTEasy file handling: extract the filename

For extracting the filename I wrote a small helper method which parses the HTTP header Content-Disposition:

/** 
* Parses the HTTP Content-Disposition header to extract the filename. If the
* header is missing or not containing a filename attribute, 'unknown' is
* returned.
* 
* Sample HTTP Content-Disposition header:
* 
* Content-Disposition=[form/data;filename="foo.txt"]
* 
* @param contentDispositionHeader
* @return the name of the uploaded file
*/
private String getFileNameOfUploadedFile(String contentDispositionHeader) {

  if (contentDispositionHeader == null || contentDispositionHeader.isEmpty()) {
    return "unkown";
  } else {
    String[] contentDispositionHeaderTokens = contentDispositionHeader.split(";");

    for (String contentDispositionHeaderToken : contentDispositionHeaderTokens) {
      if ((contentDispositionHeaderToken.trim().startsWith("filename"))) {
        return contentDispositionHeaderToken.split("=")[1].trim().replaceAll("\"", "");
      }
    }
    return "unkown";
  }
}

/**

* Parses the HTTP Content-Disposition header to extract the filename. If the

* header is missing or not containing a filename attribute, 'unknown' is

* returned.

* Sample HTTP Content-Disposition header:

* Content-Disposition=[form/data;filename="foo.txt"]

* @param contentDispositionHeader

* @return the name of the uploaded file

private String getFileNameOfUploadedFile(String contentDispositionHeader) {

if (contentDispositionHeader == null || contentDispositionHeader.isEmpty()) {

return "unkown";

} else {

String[] contentDispositionHeaderTokens = contentDispositionHeader.split(";");

for (String contentDispositionHeaderToken : contentDispositionHeaderTokens) {

if ((contentDispositionHeaderToken.trim().startsWith("filename"))) {

return contentDispositionHeaderToken.split("=")[1].trim().replaceAll("\"", "");

}

return "unkown";

}

Similarly, extracting the content type of the file is even simpler:

/**
* Parses the HTTP Content-Type header to extract the type (e.g. image/jpeg) of
* the file. If the header is missing or empty, 'unknown' is returned.
* 
* Sample HTTP Content-Type header:
* 
* Content-Type=[image/jpeg]
* 
* @param contentTypeHeader
* @return the type of the uploaded file
*/
private String getContentTypeOfUploadedFile(String contentTypeHeader) {
   if (contentTypeHeader == null || contentTypeHeader.isEmpty()) {
      return "unkown";
    } else {
      return contentTypeHeader.replace("[", "").replace("]", "");
   }
}

/**

* Parses the HTTP Content-Type header to extract the type (e.g. image/jpeg) of

* the file. If the header is missing or empty, 'unknown' is returned.

* Sample HTTP Content-Type header:

* Content-Type=[image/jpeg]

* @param contentTypeHeader

* @return the type of the uploaded file

private String getContentTypeOfUploadedFile(String contentTypeHeader) {

if (contentTypeHeader == null || contentTypeHeader.isEmpty()) {

return "unkown";

} else {

return contentTypeHeader.replace("[", "").replace("]", "");

}

The required code for downloading a file does not depend on any proprietary RESTEasy and is just JAX-RS and Java EE standard (in the example I'm offering a random file for the user to download):

@GET
@Produces(MediaType.APPLICATION_OCTET_STREAM)
public Response getRandomFile() {

 Long amountOfFiles = em.createQuery("SELECT COUNT(f) FROM FileUpload f", Long.class).getSingleResult();
 Long randomPrimaryKey;

 if (amountOfFiles == null || amountOfFiles == 0) {
  return Response.ok().build();
 } else if (amountOfFiles == 1) {
  randomPrimaryKey = 1 L;
 } else {
  randomPrimaryKey = ThreadLocalRandom.current().nextLong(1, amountOfFiles + 1);
 }

 FileUpload randomFile = em.find(FileUpload.class, randomPrimaryKey);

 return Response.ok(randomFile.getData(), MediaType.APPLICATION_OCTET_STREAM)
  .header("Content-Disposition", "attachment; filename=" + randomFile.getFileName()).build();
}

@GET

@Produces(MediaType.APPLICATION_OCTET_STREAM)

public Response getRandomFile() {

Long amountOfFiles = em.createQuery("SELECT COUNT(f) FROM FileUpload f", Long.class).getSingleResult();

Long randomPrimaryKey;

if (amountOfFiles == null || amountOfFiles == 0) {

return Response.ok().build();

} else if (amountOfFiles == 1) {

randomPrimaryKey = 1 L;

} else {

randomPrimaryKey = ThreadLocalRandom.current().nextLong(1, amountOfFiles + 1);

}

FileUpload randomFile = em.find(FileUpload.class, randomPrimaryKey);

return Response.ok(randomFile.getData(), MediaType.APPLICATION_OCTET_STREAM)

.header("Content-Disposition", "attachment; filename=" + randomFile.getFileName()).build();

}

You'll find the full code base on GitHub with an HTML page to upload files and test the implementation.

Furthermore, if you are looking for more examples to handle files (up- and download):

Have fun handling files with RESTeasy on WildFly,

Phil

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RESTEasy (WildFly – JAX-RS 2.1) file handling

Setting up the backend using RESTEasy

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