How to return a PNG image from Jersey REST service method to the browser

Question

I have a web server running with Jersey REST resources up and I wonder how to get an image png reference for the browsers img tag  after submitting a Form or getting an Ajax response  The image processing code for adding graphics is working  just need to return it somehow   Code    POST  Path   fullsize     Consumes MediaType MULTIPART FORM DATA   Produces  image png      Would need to replace void public void getFullImage  FormDataParam  photo   InputStream imageIS                            FormDataParam  submit   String extra           BufferedImage image   ImageIO read imageIS                  image processing              image processing        return ImageIO              Cheers

User · Answer

I built a general method for that with following features:

returning "not modified" if the file hasn't been modified locally, a Status.NOT_MODIFIED is sent to the caller. Uses Apache Commons Lang
using a file stream object instead of reading the file itself

Here the code:

import org.apache.commons.lang3.time.DateUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

private static final Logger logger = LoggerFactory.getLogger(Utils.class);

@GET
@Path("16x16")
@Produces("image/png")
public Response get16x16PNG(@HeaderParam("If-Modified-Since") String modified) {
    File repositoryFile = new File("c:/temp/myfile.png");
    return returnFile(repositoryFile, modified);
}

/**
 * 
 * Sends the file if modified and "not modified" if not modified
 * future work may put each file with a unique id in a separate folder in tomcat
 *   * use that static URL for each file
 *   * if file is modified, URL of file changes
 *   * -> client always fetches correct file 
 * 
 *     method header for calling method public Response getXY(@HeaderParam("If-Modified-Since") String modified) {
 * 
 * @param file to send
 * @param modified - HeaderField "If-Modified-Since" - may be "null"
 * @return Response to be sent to the client
 */
public static Response returnFile(File file, String modified) {
    if (!file.exists()) {
        return Response.status(Status.NOT_FOUND).build();
    }

    // do we really need to send the file or can send "not modified"?
    if (modified != null) {
        Date modifiedDate = null;

        // we have to switch the locale to ENGLISH as parseDate parses in the default locale
        Locale old = Locale.getDefault();
        Locale.setDefault(Locale.ENGLISH);
        try {
            modifiedDate = DateUtils.parseDate(modified, org.apache.http.impl.cookie.DateUtils.DEFAULT_PATTERNS);
        } catch (ParseException e) {
            logger.error(e.getMessage(), e);
        }
        Locale.setDefault(old);

        if (modifiedDate != null) {
            // modifiedDate does not carry milliseconds, but fileDate does
            // therefore we have to do a range-based comparison
            // 1000 milliseconds = 1 second
            if (file.lastModified()-modifiedDate.getTime() < DateUtils.MILLIS_PER_SECOND) {
                return Response.status(Status.NOT_MODIFIED).build();
            }
        }
    }        
    // we really need to send the file

    try {
        Date fileDate = new Date(file.lastModified());
        return Response.ok(new FileInputStream(file)).lastModified(fileDate).build();
    } catch (FileNotFoundException e) {
        return Response.status(Status.NOT_FOUND).build();
    }
}

/*** copied from org.apache.http.impl.cookie.DateUtils, Apache 2.0 License ***/

/**
 * Date format pattern used to parse HTTP date headers in RFC 1123 format.
 */
public static final String PATTERN_RFC1123 = "EEE, dd MMM yyyy HH:mm:ss zzz";

/**
 * Date format pattern used to parse HTTP date headers in RFC 1036 format.
 */
public static final String PATTERN_RFC1036 = "EEEE, dd-MMM-yy HH:mm:ss zzz";

/**
 * Date format pattern used to parse HTTP date headers in ANSI C
 * <code>asctime()</code> format.
 */
public static final String PATTERN_ASCTIME = "EEE MMM d HH:mm:ss yyyy";

public static final String[] DEFAULT_PATTERNS = new String[] {
    PATTERN_RFC1036,
    PATTERN_RFC1123,
    PATTERN_ASCTIME
};

Note that the Locale switching does not seem to be thread-safe. I think, it's better to switch the locale globally. I am not sure about the side-effects though...

User · Answer

in regard of answer from  Perception  its true to be very memory-consuming when working with byte arrays  but you could also simply write back into the outputstream   Path   picture   public class ProfilePicture      GET    Path   thumbnail      Produces  image png     public StreamingOutput getThumbNail         return new StreamingOutput            Override       public void write OutputStream os  throws IOException  WebApplicationException                 read your stream and write into os

User · Answer

If you have a number of image resource methods  it is well worth creating a MessageBodyWriter to output the BufferedImage    Produces    image png    image jpg      Provider public class BufferedImageBodyWriter implements MessageBodyWriter lt BufferedImage gt        Override   public boolean isWriteable Class lt   gt  type  Type type1  Annotation   antns  MediaType mt        return type    BufferedImage class          Override   public long getSize BufferedImage t  Class lt   gt  type  Type type1  Annotation   antns  MediaType mt        return -1     not used in JAX-RS 2         Override   public void writeTo BufferedImage image  Class lt   gt  type  Type type1  Annotation   antns  MediaType mt  MultivaluedMap lt String  Object gt  mm  OutputStream out  throws IOException  WebApplicationException       ImageIO write image  mt getSubtype    out            This MessageBodyWriter will be used automatically if auto-discovery is enabled for Jersey  otherwise it needs to be returned by a custom Application sub-class  See JAX-RS Entity Providers for more info   Once this is set up  simply return a BufferedImage from a resource method and it will be be output as image file data    Path   whatever    Produces   image png    image jpg    public Response getFullImage          BufferedImage image          return Response ok image  build        A couple of advantages to this approach    It writes to the response OutputSteam rather than an intermediary BufferedOutputStream It supports both png and jpg output  depending on the media types allowed by the resource method

User · Answer

I m not convinced its a good idea to return image data in a REST service  It ties up your application server s memory and IO bandwidth  Much better to delegate that task to a proper web server that is optimized for this kind of transfer  You can accomplish this by sending a redirect to the image resource  as a HTTP 302 response with the URI of the image   This assumes of course that your images are arranged as web content   Having said that  if you decide you really need to transfer image data from a web service you can do so with the following  pseudo  code    Path   whatever    Produces  image png   public Response getFullImage             BufferedImage image             ByteArrayOutputStream baos   new ByteArrayOutputStream        ImageIO write image   png   baos       byte   imageData   baos toByteArray            uncomment line below to send non-streamed        return Response ok imageData  build            uncomment line below to send streamed        return Response ok new ByteArrayInputStream imageData   build        Add in exception handling  etc etc

[java] How to return a PNG image from Jersey REST service method to the browser

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