Introduction
JAX-RS or Java API for RESTful Web Services is a Java API used to create web services. JAX-RS, like JAX-WS, uses annotations to simplify the development and deployment of web services. Jersey is an implementation of JAX-RS API but is not part of standard JDK. Hence, we have to include all the required jars to use Jersey. We shall see an example of a JAX-RS file upload using Jersey.
JAX-RS file upload
To upload a file using JAX-RS API with Jersy implementation, we require the Jersey jar files. Download them from here.
We make use of two main annotations for this example.
-
The @FormDataParam("file") annotation takes a file as a parameter in the service class.
-
The @Consumes(MediaType.MULTIPART_FORM_DATA) annotation provides MIME information about the uploaded file.
-
The @Path annotation defines the relative URI path for the RESTful resource.
-
The @POST annotation is a request method designator to process HTTP POST requests.
Here is the code to upload a file using the JAX-RS API.
package fileUploadService;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import javax.ws.rs.Consumes;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import org.glassfish.jersey.media.multipart.FormDataContentDisposition;
import org.glassfish.jersey.media.multipart.FormDataParam;
@Path("/files")
public class FileUpload {
@POST
@Path("/upload")
@Consumes(MediaType.MULTIPART_FORM_DATA)
public Response fileUpload(
@FormDataParam("file") InputStream uploadedInputStream,
@FormDataParam("file") FormDataContentDisposition detail) {
String fileLoc = "D://" + detail.getFileName();
//saving file
try {
FileOutputStream fout = new FileOutputStream(new File(fileLoc));
int read = 0;
byte[] bytes = new byte[1024];
fout = new FileOutputStream(new File(fileLoc));
while ((read = uploadedInputStream.read(bytes)) != -1) {
fout.write(bytes, 0, read);
}
fout.flush();
fout.close();
} catch (IOException e) {e.printStackTrace();}
String display = "The file has been uploaded to : " + fileLoc;
return Response.status(200).entity(display).build();
}
} 
You can also try this code with Online Java Compiler
Following is the content of the web.xml file.
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<servlet>
<servlet-name>Jersey REST Service</servlet-name>
<servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
<init-param>
<param-name>jersey.config.server.provider.packages</param-name>
<param-value>fileUploadService</param-value>
</init-param>
<init-param>
<param-name>jersey.config.server.provider.classnames</param-name>
<param-value>org.glassfish.jersey.filter.LoggingFilter;
org.glassfish.jersey.media.multipart.MultiPartFeature</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>Jersey REST Service</servlet-name>
<url-pattern>/rest/*</url-pattern>
</servlet-mapping>
</web-app> Index.html
<!DOCTYPE HTML>
<html>
<body>
<h1>File Upload example with Jersey</h1>
<form action="rest/files/upload" method="post" enctype="multipart/form-data">
Select a file: <input type="file" name="file" size="50" />
<br/><br/>
<input type="submit" value="Upload" />
</form>
</body>
</html>Output:
Choose a file
Click on Upload.
The file is uploaded.
34+ registered 
