PhotosResource
The PhotosResource class shows examples of the following:
-
How to define custom serializers and parsers at the method level.
In this case, you define a serializer and parser to handle images.
The resource consists of a simple registry of images with integer IDs.
http://localhost:10000/photos
It is initialized with a single entry, which can be accessed through a GET request.
http://localhost:10000/photos/cat
/**
* Sample resource that allows images to be uploaded and retrieved.
*/
@RestResource(
path="/photos",
messages="nls/PhotosResource",
title="Photo REST service",
description="Sample resource that allows images to be uploaded and retrieved.",
htmldoc=@HtmlDoc(
navlinks={
"up: request:/..",
"options: servlet:/?method=OPTIONS",
"source: $C{Source/gitHub}/org/apache/juneau/examples/rest/$R{servletClassSimple}.java"
},
aside={
"<div style='max-width:400px;min-width:200px' class='text'>",
" <p>Shows an example of using custom serializers and parsers to create REST interfaces over binary resources.</p>",
" <p>In this case, our resources are marshalled jpeg and png binary streams and are stored in an in-memory 'database' (also known as a <code>TreeMap</code>).</p>",
"</div>"
}
),
properties={
// Make the anchor text on URLs be just the path relative to the servlet.
@Property(name=HTML_uriAnchorText, value="SERVLET_RELATIVE")
}
)
public class PhotosResource extends BasicRestServlet {
// Our cache of photos
private Map<String,Photo> photos = new TreeMap<>();
@Override /* Servlet */
public void init() {
try (InputStream is = getClass().getResourceAsStream("averycutecat.jpg")) {
BufferedImage image = ImageIO.read(is);
Photo photo = new Photo("cat", image);
photos.put(photo.id, photo);
} catch (IOException e) {
throw new RuntimeException(e);
}
}
/** Bean class for storing photos */
public static class Photo {
private String id;
BufferedImage image;
Photo(String id, BufferedImage image) {
this.id = id;
this.image = image;
}
public URI getURI() throws URISyntaxException {
return new URI("servlet:/" + id);
}
}
/** GET request handler for list of all photos */
@RestMethod(name=GET, path="/", summary="Show the list of all currently loaded photos")
public Collection<Photo> getAllPhotos() throws Exception {
return photos.values();
}
/** GET request handler for single photo */
@RestMethod(name=GET, path="/{id}", serializers=ImageSerializer.class, summary="Get a photo by ID")
public BufferedImage getPhoto(@Path("id") String id) throws Exception {
Photo p = photos.get(id);
if (p == null)
throw new RestException(SC_NOT_FOUND, "Photo not found");
return p.image;
}
/** PUT request handler */
@RestMethod(name=PUT, path="/{id}", parsers=ImageParser.class, summary="Add or overwrite a photo")
public String addPhoto(@Path("id") String id, @Body BufferedImage image) throws Exception {
photos.put(id, new Photo(id, image));
return "OK";
}
/** POST request handler */
@RestMethod(name=POST, path="/", parsers=ImageParser.class, summary="Add a photo")
public Photo setPhoto(@Body BufferedImage image) throws Exception {
Photo p = new Photo(UUID.randomUUID().toString(), image);
photos.put(p.id, p);
return p;
}
/** DELETE request handler */
@RestMethod(name=DELETE, path="/{id}", summary="Delete a photo by ID")
public String deletePhoto(@Path("id") String id) throws Exception {
Photo p = photos.remove(id);
if (p == null)
throw new RestException(SC_NOT_FOUND, "Photo not found");
return "OK";
}
/** Serializer for converting images to byte streams */
public static class ImageSerializer extends OutputStreamSerializer {
/**
* Constructor.
* @param ps The property store containing all the settings for this object.
*/
public ImageSerializer(PropertyStore ps) {
super(ps, null, "image/png", "image/jpeg");
}
@Override /* Serializer */
public OutputStreamSerializerSession createSession(SerializerSessionArgs args) {
return new OutputStreamSerializerSession(args) {
@Override /* SerializerSession */
protected void doSerialize(SerializerPipe out, Object o) throws Exception {
RenderedImage image = (RenderedImage)o;
String mediaType = getProperty("mediaType", String.class, (String)null);
ImageIO.write(image, mediaType.substring(mediaType.indexOf('/')+1), out.getOutputStream());
}
};
}
}
/** Parser for converting byte streams to images */
public static class ImageParser extends InputStreamParser {
/**
* Constructor.
* @param ps The property store containing all the settings for this object.
*/
public ImageParser(PropertyStore ps) {
super(ps, "image/png", "image/jpeg");
}
@Override /* Parser */
public InputStreamParserSession createSession(final ParserSessionArgs args) {
return new InputStreamParserSession(args) {
@Override /* ParserSession */
@SuppressWarnings("unchecked")
protected <T> T doParse(ParserPipe pipe, ClassMeta<T> type) throws Exception {
return (T)ImageIO.read(pipe.getInputStream());
}
};
}
}
}