Add SockJsFrameType enum

SPR-10797

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/frame/DefaultSockJsFrameFormat.java

@@ -19,6 +19,10 @@ package org.springframework.web.socket.sockjs.frame;
 import org.springframework.util.Assert;
 
 /**
+ * A default implementation of
+ * {@link org.springframework.web.socket.sockjs.frame.SockJsFrameFormat} that relies
+ * on {@link java.lang.String#format(String, Object...)}..
+ *
  * @author Rossen Stoyanchev
  * @since 4.0
  */
@@ -33,14 +37,9 @@ public class DefaultSockJsFrameFormat implements SockJsFrameFormat {
 	}
 
 
-	/**
-	 * @param frame the SockJs frame.
-	 * @return new SockJsFrame instance with the formatted content
-	 */
 	@Override
-	public SockJsFrame format(SockJsFrame frame) {
-		String content = String.format(this.format, preProcessContent(frame.getContent()));
-		return new SockJsFrame(content);
+	public String format(SockJsFrame frame) {
+		return String.format(this.format, preProcessContent(frame.getContent()));
 	}
 
 	protected String preProcessContent(String content) {

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/frame/SockJsFrame.java

@@ -18,18 +18,17 @@ package org.springframework.web.socket.sockjs.frame;
 
 import java.nio.charset.Charset;
 
-import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
 
 /**
- * Represents a SockJS frame. Provides factory methods to create SockJS frames on
- * the server side.
+ * Represents a SockJS frame. Provides factory methods to create SockJS frames.
  *
  * @author Rossen Stoyanchev
  * @since 4.0
  */
 public class SockJsFrame {
 
-	private static final Charset UTF8_CHARSET = Charset.forName("UTF-8");
+	public static final Charset CHARSET = Charset.forName("UTF-8");
 
 	private static final SockJsFrame OPEN_FRAME = new SockJsFrame("o");
 
@@ -40,12 +39,40 @@ public class SockJsFrame {
 	private static final SockJsFrame CLOSE_ANOTHER_CONNECTION_OPEN_FRAME = closeFrame(2010, "Another connection still open");
 
 
+	private final SockJsFrameType type;
+
 	private final String content;
 
 
+	/**
+	 * Create a new instance frame with the given frame content.
+	 * @param content the content, must be a non-empty and represent a valid SockJS frame
+	 */
 	public SockJsFrame(String content) {
-		Assert.notNull("Content must not be null");
-		this.content = content;
+		StringUtils.hasText(content);
+		if ("o".equals(content)) {
+			this.type = SockJsFrameType.OPEN;
+			this.content = content;
+		}
+		else if ("h".equals(content)) {
+			this.type = SockJsFrameType.HEARTBEAT;
+			this.content = content;
+		}
+		else if (content.charAt(0) == 'a') {
+			this.type = SockJsFrameType.MESSAGE;
+			this.content = (content.length() > 1 ? content : "a[]");
+		}
+		else if (content.charAt(0) == 'm') {
+			this.type = SockJsFrameType.MESSAGE;
+			this.content = (content.length() > 1 ? content : "null");
+		}
+		else if (content.charAt(0) == 'c') {
+			this.type = SockJsFrameType.CLOSE;
+			this.content = (content.length() > 1 ? content : "c[]");
+		}
+		else {
+			throw new IllegalArgumentException("Unexpected SockJS frame type in content=\"" + content + "\"");
+		}
 	}
 
 	public static SockJsFrame openFrame() {
@@ -74,12 +101,39 @@ public class SockJsFrame {
 	}
 
 
+	/**
+	 * Return the SockJS frame type.
+	 */
+	public SockJsFrameType getType() {
+		return this.type;
+	}
+
+	/**
+	 * Return the SockJS frame content, never {@code null}.
+	 */
 	public String getContent() {
 		return this.content;
 	}
 
+	/**
+	 * Return the SockJS frame content as a byte array.
+	 */
 	public byte[] getContentBytes() {
-		return this.content.getBytes(UTF8_CHARSET);
+		return this.content.getBytes(CHARSET);
+	}
+
+	/**
+	 * Return data contained in a SockJS "message" and "close" frames. Otherwise
+	 * for SockJS "open" and "close" frames, which do not contain data, return
+	 * {@code null}.
+	 */
+	public String getFrameData() {
+		if (SockJsFrameType.OPEN == getType() || SockJsFrameType.HEARTBEAT == getType()) {
+			return null;
+		}
+		else {
+			return getContent().substring(1);
+		}
 	}
 
 

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/frame/SockJsFrameFormat.java

@@ -17,11 +17,22 @@
 package org.springframework.web.socket.sockjs.frame;
 
 /**
+ * Applies a transport-specific format to the content of a SockJS frame resulting
+ * in a content that can be written out. Primarily for use in HTTP server-side
+ * transports that push data.
+ *
+ * <p>Formatting may vary from simply appending a new line character for XHR
+ * polling and streaming transports, to a jsonp-style callback function,
+ * surrounding script tags, and more.
+ *
+ * <p>For the various SockJS frame formats in use, see implementations of
+ * {@link  org.springframework.web.socket.sockjs.transport.handler.AbstractHttpSendingTransportHandler#getFrameFormat(org.springframework.http.server.ServerHttpRequest) AbstractHttpSendingTransportHandler.getFrameFormat}
+ *
  * @author Rossen Stoyanchev
  * @since 4.0
  */
 public interface SockJsFrameFormat {
 
-	SockJsFrame format(SockJsFrame frame);
+	String format(SockJsFrame frame);
 
 }

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/frame/SockJsFrameType.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2002-2014 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.socket.sockjs.frame;
+
+/**
+ * SockJS frame types.
+ *
+ * @author Rossen Stoyanchev
+ * @since 4.1
+ */
+public enum SockJsFrameType {
+
+	OPEN, HEARTBEAT, MESSAGE, CLOSE
+
+}

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/handler/AbstractHttpSendingTransportHandler.java

@@ -82,12 +82,12 @@ public abstract class AbstractHttpSendingTransportHandler extends AbstractTransp
 		}
 		else {
 			logger.debug("another " + getTransportType() + " connection still open: " + sockJsSession);
-			SockJsFrame frame = getFrameFormat(request).format(SockJsFrame.closeFrameAnotherConnectionOpen());
+			String formattedFrame = getFrameFormat(request).format(SockJsFrame.closeFrameAnotherConnectionOpen());
 			try {
-				response.getBody().write(frame.getContentBytes());
+				response.getBody().write(formattedFrame.getBytes(SockJsFrame.CHARSET));
 			}
 			catch (IOException ex) {
-				throw new SockJsException("Failed to send " + frame, sockJsSession.getId(), ex);
+				throw new SockJsException("Failed to send " + formattedFrame, sockJsSession.getId(), ex);
 			}
 		}
 	}

spring-websocket/src/main/java/org/springframework/web/socket/sockjs/transport/session/AbstractHttpSockJsSession.java

@@ -351,11 +351,11 @@ public abstract class AbstractHttpSockJsSession extends AbstractSockJsSession {
 	@Override
 	protected void writeFrameInternal(SockJsFrame frame) throws IOException {
 		if (isActive()) {
-			frame = this.frameFormat.format(frame);
+			String formattedFrame = this.frameFormat.format(frame);
 			if (logger.isTraceEnabled()) {
-				logger.trace("Writing " + frame);
+				logger.trace("Writing " + formattedFrame);
 			}
-			getResponse().getBody().write(frame.getContentBytes());
+			getResponse().getBody().write(formattedFrame.getBytes(SockJsFrame.CHARSET));
 		}
 	}