New feature: uploading a file (e.g., an image) with each message.

MessageBoard/src/edu/gac/mcs270/messageboard/client/MessageBoard.java

@@ -2,6 +2,8 @@
 
 import java.util.List;
 
+import edu.gac.mcs270.messageboard.shared.BlobService;
+import edu.gac.mcs270.messageboard.shared.BlobServiceAsync;
 import edu.gac.mcs270.messageboard.shared.Message;
 import edu.gac.mcs270.messageboard.shared.MessageStore;
 import edu.gac.mcs270.messageboard.shared.MessageStoreAsync;
@@ -13,23 +15,34 @@
 import com.google.gwt.event.dom.client.ClickHandler;
 import com.google.gwt.user.client.DOM;
 import com.google.gwt.user.client.Timer;
+import com.google.gwt.user.client.Window;
 import com.google.gwt.user.client.rpc.AsyncCallback;
+import com.google.gwt.user.client.ui.Anchor;
 import com.google.gwt.user.client.ui.Button;
+import com.google.gwt.user.client.ui.FileUpload;
+import com.google.gwt.user.client.ui.FormPanel;
+import com.google.gwt.user.client.ui.FormPanel.SubmitEvent;
 import com.google.gwt.user.client.ui.HorizontalPanel;
 import com.google.gwt.user.client.ui.Label;
 import com.google.gwt.user.client.ui.RootPanel;
 import com.google.gwt.user.client.ui.TextBox;
 import com.google.gwt.user.client.ui.VerticalPanel;
+import com.google.gwt.user.client.ui.FormPanel.SubmitCompleteEvent;
 
 /**
  * User interface for the message board.
+ * The feature to store images in Blobstore uses code taken from the BlobStore Tutorial
+ * written by the blogger "fishbone":
+ *  http://www.fishbonecloud.com/2010/12/tutorial-gwt-application-for-storing.html
  * @author max
  */
 public class MessageBoard implements EntryPoint {
 	// The interval in milliseconds between periodic updates.
 	private static final int UPDATE_INTERVAL_MS = 10000;
 	private final MessageStoreAsync messageStore = GWT
 			.create(MessageStore.class);
+	private final BlobServiceAsync blobService = GWT
+			.create(BlobService.class);
 	private VerticalPanel messagesPanel;
 	private Label updatingLabel;
 	private Label failureLabel;
@@ -40,10 +53,12 @@ public class MessageBoard implements EntryPoint {
 	 */
 	public void onModuleLoad() {
 		final VerticalPanel mainPanel = new VerticalPanel();
+		final FormPanel uploadForm = new FormPanel();
 		final HorizontalPanel entryPanel = new HorizontalPanel();
 		entryPanel.addStyleName("entryPanel");
-		mainPanel.add(entryPanel);
-
+		mainPanel.add(uploadForm);
+		uploadForm.add(entryPanel);
+
 		final Label authorLabel = new Label("Author:");
 		final TextBox authorField = new TextBox();
 		entryPanel.add(authorLabel);
@@ -54,9 +69,23 @@ public void onModuleLoad() {
 		entryPanel.add(textLabel);
 		entryPanel.add(textField);
 
+		final FileUpload upload = new FileUpload();
+		entryPanel.add(upload);
+
 		final Button postButton = new Button("Post");
 		entryPanel.add(postButton);
-
+
+		// The upload form, when submitted, will trigger an HTTP call to the
+		// servlet.  The following parameters must be set
+		uploadForm.setEncoding(FormPanel.ENCODING_MULTIPART);
+		uploadForm.setMethod(FormPanel.METHOD_POST);
+
+		// Set Names for the text boxes so that they can be retrieved from the
+		// HTTP call as parameters
+		authorField.setName("author");
+		textField.setName("text");
+		upload.setName("upload");
+
 		final HorizontalPanel statusPanel = new HorizontalPanel();
 		statusPanel.setHeight("3em");
 		updatingLabel = new Label("Updating...");
@@ -74,28 +103,61 @@ public void onModuleLoad() {
 		postButton.addClickHandler(new ClickHandler(){
 			@Override
 			public void onClick(ClickEvent event) {
-				messageStore.storeMessage(
-						new Message(
-								authorField.getText(),
-								textField.getText()),
-						new AsyncCallback<Void>(){
-							@Override
-							public void onFailure(Throwable caught) {
-								failureLabel.setVisible(true);
-							}
-
-							@Override
-							public void onSuccess(Void result) {
-								failureLabel.setVisible(false);
-								updateMessages();
-							}
-						});
-				authorField.setText("");
-				textField.setText("");
+
+				blobService
+				.getBlobStoreUploadUrl(new AsyncCallback<String>() {
+
+					@Override
+					public void onSuccess(String result) {
+						// Set the form action to the newly created
+						// blobstore upload URL
+						uploadForm.setAction(result.toString());
+
+						// Submit the form to complete the upload
+						uploadForm.submit();
+					}
+
+					@Override
+					public void onFailure(Throwable caught) {
+						failureLabel.setVisible(true);
+					}
+				});
+
+			}
+		});
+
+		uploadForm.addSubmitHandler(new FormPanel.SubmitHandler() {
+			public void onSubmit(SubmitEvent event) {
+				// This event is fired just before the form is submitted. We can take
+				// this opportunity to perform validation.
+				if (authorField.getText().length() == 0) {
+					Window.alert("The author is required.");
+					event.cancel();
+				}
+				if (textField.getText().length() == 0) {
+					Window.alert("The text is required.");
+					event.cancel();
+				}
+				if (upload.getFilename().length() == 0) {
+					Window.alert("The upload file is required.");
+					event.cancel();
+				}
+			}
+		});
+
+
+		uploadForm
+		.addSubmitCompleteHandler(new FormPanel.SubmitCompleteHandler() {
+			@Override
+			public void onSubmitComplete(SubmitCompleteEvent event) {
+				failureLabel.setVisible(false);
+				updateMessages();
+				uploadForm.reset();
 				authorField.setFocus(true);
 			}
+
 		});
-		
+
 		updateMessages();
 		new Timer(){
 			@Override
@@ -133,6 +195,9 @@ public void onSuccess(List<Message> result) {
 							Label heading = new Label(m.getAuthor());
 							heading.addStyleName("messageHeading");
 							messagesPanel.insert(heading, position++);
+							Anchor link = new Anchor("uploaded file", m.getURL());
+							link.setTarget("_blank");
+							messagesPanel.insert(link, position++);
 							Label body = new Label(m.getText());
 							body.addStyleName("messageBody");
 							messagesPanel.insert(body, position++);

MessageBoard/src/edu/gac/mcs270/messageboard/server/BlobServiceImpl.java

@@ -0,0 +1,49 @@
+package edu.gac.mcs270.messageboard.server;
+
+import java.io.IOException;
+
+import javax.jdo.PersistenceManager;
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import edu.gac.mcs270.messageboard.shared.BlobService;
+
+import com.google.appengine.api.blobstore.BlobKey;
+import com.google.appengine.api.blobstore.BlobstoreService;
+import com.google.appengine.api.blobstore.BlobstoreServiceFactory;
+import com.google.gwt.user.server.rpc.RemoteServiceServlet;
+
+/* This is extracted from code in the BlobStore Tutorial written by the blogger "fishbone":
+ *  http://www.fishbonecloud.com/2010/12/tutorial-gwt-application-for-storing.html */
+
+@SuppressWarnings("serial")
+public class BlobServiceImpl extends RemoteServiceServlet implements
+    BlobService {
+
+  //Start a GAE BlobstoreService session and persistence manager
+  BlobstoreService blobstoreService = BlobstoreServiceFactory
+      .getBlobstoreService();
+  PersistenceManager pm = PMF.get().getPersistenceManager();
+
+  //Generate a Blobstore Upload URL from the GAE BlobstoreService
+  @Override
+  public String getBlobStoreUploadUrl() {
+
+    //Map the UploadURL to the uploadservice which will be called by
+    //submitting the FormPanel
+    return blobstoreService
+        .createUploadUrl("/messageboard/uploadservice");
+  }
+
+  //Override doGet to serve blobs.  This will be called when an uploaded file is viewed
+  //in the client
+  @Override
+  protected void doGet(HttpServletRequest req, HttpServletResponse resp)
+      throws ServletException, IOException {
+
+        BlobKey blobKey = new BlobKey(req.getParameter("blob-key"));
+        blobstoreService.serve(blobKey, resp);
+
+  }
+}

MessageBoard/src/edu/gac/mcs270/messageboard/server/MessageStoreImpl.java

@@ -8,7 +8,6 @@
 
 import com.google.gwt.user.server.rpc.RemoteServiceServlet;
 
-import javax.jdo.JDOHelper;
 import javax.jdo.PersistenceManagerFactory;
 import javax.jdo.PersistenceManager;
 import javax.jdo.Query;
@@ -21,16 +20,9 @@
 public class MessageStoreImpl extends RemoteServiceServlet implements
 MessageStore {
 
-	private static final long serialVersionUID = 7367373321119740703L;
+	private static final long serialVersionUID = 2637409426426537753L;
 
-	private static final PersistenceManagerFactory pmf =
-			JDOHelper.getPersistenceManagerFactory("transactions-optional");
-
-	@Override
-	public void storeMessage(Message msg) {
-		PersistenceManager pm = pmf.getPersistenceManager();
-		pm.makePersistent(msg);
-	}
+	private static final PersistenceManagerFactory pmf = PMF.get();
 
 	@Override
 	public List<Message> getMessages(Long minimumID) {

MessageBoard/src/edu/gac/mcs270/messageboard/server/PMF.java

@@ -0,0 +1,15 @@
+package edu.gac.mcs270.messageboard.server;
+
+import javax.jdo.JDOHelper;
+import javax.jdo.PersistenceManagerFactory;
+
+public final class PMF {
+ private static final PersistenceManagerFactory pmfInstance =
+     JDOHelper.getPersistenceManagerFactory("transactions-optional");
+
+ private PMF() {}
+
+ public static PersistenceManagerFactory get() {
+   return pmfInstance;
+ }
+}

MessageBoard/src/edu/gac/mcs270/messageboard/server/UploadServiceImpl.java

@@ -0,0 +1,52 @@
+package edu.gac.mcs270.messageboard.server;
+
+import java.io.IOException;
+import java.util.Map;
+
+import javax.jdo.PersistenceManager;
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import com.google.appengine.api.blobstore.BlobKey;
+import com.google.appengine.api.blobstore.BlobstoreService;
+import com.google.appengine.api.blobstore.BlobstoreServiceFactory;
+
+import edu.gac.mcs270.messageboard.shared.Message;
+
+/* This is adapted from code in the BlobStore Tutorial written by the blogger "fishbone":
+ *  http://www.fishbonecloud.com/2010/12/tutorial-gwt-application-for-storing.html */
+
+//The FormPanel must submit to a servlet that extends HttpServlet  
+//RemoteServiceServlet cannot be used
+@SuppressWarnings("serial")
+public class UploadServiceImpl extends HttpServlet {
+
+	//Start Blobstore and persistence manager
+	BlobstoreService blobstoreService = BlobstoreServiceFactory
+			.getBlobstoreService();
+	PersistenceManager pm = PMF.get().getPersistenceManager();
+
+	//Override the doPost method to store the Blob's meta-data
+	@Override
+	public void doPost(HttpServletRequest req, HttpServletResponse res)
+			throws ServletException, IOException {
+
+		@SuppressWarnings("deprecation")
+		Map<String, BlobKey> blobs = blobstoreService.getUploadedBlobs(req);
+		BlobKey blobKey = blobs.get("upload");
+
+		//Get the paramters from the request to populate the Message object
+		Message msg = 
+				new Message(
+						req.getParameter("author"), 
+						req.getParameter("text"),
+						//Map the ImageURL to the blobservice servlet, which will serve the image
+						"/messageboard/blobservice?blob-key=" + blobKey.getKeyString()
+						);
+
+		pm.makePersistent(msg);
+	}
+
+}

MessageBoard/src/edu/gac/mcs270/messageboard/shared/BlobService.java

@@ -0,0 +1,14 @@
+package edu.gac.mcs270.messageboard.shared;
+
+import com.google.gwt.user.client.rpc.RemoteService;
+import com.google.gwt.user.client.rpc.RemoteServiceRelativePath;
+
+/* This is extracted from code in the BlobStore Tutorial written by the blogger "fishbone":
+ *  http://www.fishbonecloud.com/2010/12/tutorial-gwt-application-for-storing.html */
+
+@RemoteServiceRelativePath("blobservice")
+public interface BlobService extends RemoteService {
+
+  String getBlobStoreUploadUrl();
+
+}

MessageBoard/src/edu/gac/mcs270/messageboard/shared/BlobServiceAsync.java

@@ -0,0 +1,9 @@
+package edu.gac.mcs270.messageboard.shared;
+
+import com.google.gwt.user.client.rpc.AsyncCallback;
+
+public interface BlobServiceAsync {
+
+	void getBlobStoreUploadUrl(AsyncCallback<String> callback);
+
+}

MessageBoard/src/edu/gac/mcs270/messageboard/shared/Message.java

@@ -14,13 +14,16 @@
  */
 @PersistenceCapable(identityType=IdentityType.APPLICATION)
 public class Message implements Serializable{
-	private static final long serialVersionUID = 1L;
+	private static final long serialVersionUID = 2L;
 
 	@Persistent
 	private String author;
 
 	@Persistent
 	private String text;
+
+	@Persistent
+	private String url;
 
 	@PrimaryKey
 	@Persistent(valueStrategy=IdGeneratorStrategy.IDENTITY)
@@ -29,10 +32,12 @@ public class Message implements Serializable{
 	/**
 	 * @param author the name of the Message's author
 	 * @param text the body of the Message
+	 * @param url the URL of the uploaded file
 	 */
-	public Message(String author, String text) {
+	public Message(String author, String text, String url) {
 		this.author = author;
 		this.text = text;
+		this.url = url;
 	}
 
 	/**
@@ -49,6 +54,13 @@ public String getText() {
 		return text;
 	}
 
+	/**
+	 * @return the URL of the file uploaded with this Message
+	 */
+	public String getURL() {
+		return url;
+	}
+
 	/**
 	 * @return the id of this Message
 	 */