Jersey Exception Handling
Jersey ExceptionMapper – Create custom exceptions
To handle custom exception in JAX-RS based web services, you should create an exception class and then implement the ExceptionMapper interface.
@Provider
public class MissingFileException extends Exception
implements ExceptionMapper<MissingFileException> {
private static final long serialVersionUID = 1L;
public MissingFileException() {
super("No File found with given name !!");
}
public MissingFileException(String string) {
super(string);
}
@Override
public Response toResponse(MissingFileException exception) {
return Response.status(404).entity(exception.getMessage())
.type(MediaType.TEXT_PLAIN).build();
}
}
How to throw exception from REST API
public class DownloadService {
@GET
@Path("/{fileName}")
public Response downloadFile(final @PathParam("fileName") String fileName)
throws MissingFileException {
final String fullFilePath = Globals.UPLOAD_PATH + fileName;
File file = new File(fullFilePath);
if (file.exists() == false) {
throw new MissingFileException(
fileName + " does not existing on this server !!");
}
StreamingOutput fileStream = new StreamingOutput() {
@Override
public void write(java.io.OutputStream output) throws IOException {
try {
java.nio.file.Path path = Paths.get(fullFilePath);
byte[] data = Files.readAllBytes(path);
output.write(data);
output.flush();
} catch (IOException e) {
throw new IOException("Error while reading file :: '"
+ fileName + "' !!");
}
}
};
return Response.ok(fileStream, MediaType.APPLICATION_OCTET_STREAM)
.header("content-disposition",
"attachment; filename = '" + fileName)
.build();
}
}
Uncaught Exception Handling
If you want to handle all uncaught exception before going to user screen, you will have to map the Throwable itself.
@Provider
public class UncaughtException extends Throwable
implements ExceptionMapper<Throwable> {
private static final long serialVersionUID = 1L;
@Override
public Response toResponse(Throwable exception) {
return Response.status(500)
.entity("Something bad happened. Please try again !!")
.type(MediaType.TEXT_PLAIN).build();
}
}