Add option to copy HTTP session id to handshake attrs

Issue: SPR-12314

Author: rstoyanchev

spring-websocket/src/main/java/org/springframework/web/socket/server/support/HttpSessionHandshakeInterceptor.java

@@ -38,7 +38,15 @@
  */
 public class HttpSessionHandshakeInterceptor implements HandshakeInterceptor {
 
-	private Collection<String> attributeNames;
+	/**
+	 * The name of the attribute under which the HTTP session id is exposed when
+	 * {@link #setCopyHttpSessionId(boolean) copyHttpSessionId} is "true".
+	 */
+	public static final String HTTP_SESSION_ID_ATTR_NAME = "HTTP.SESSION.ID";
+
+	private final Collection<String> attributeNames;
+
+	private boolean copyHttpSessionId;
 
 
 	/**
@@ -56,6 +64,25 @@ public HttpSessionHandshakeInterceptor(Collection<String> attributeNames) {
 		this.attributeNames = attributeNames;
 	}
 
+	/**
+	 * When set to "true", the HTTP session id is copied to the WebSocket
+	 * handshake attributes, and is subsequently available via
+	 * {@link org.springframework.web.socket.WebSocketSession#getAttributes()}
+	 * under the key {@link #HTTP_SESSION_ID_ATTR_NAME}.
+	 * <p>By default this is "false".
+	 * @param copyHttpSessionId whether to copy the HTTP session id.
+	 */
+	public void setCopyHttpSessionId(boolean copyHttpSessionId) {
+		this.copyHttpSessionId = copyHttpSessionId;
+	}
+
+	/**
+	 * Whether to copy the HTTP session id to the handshake attributes.
+	 */
+	public boolean isCopyHttpSessionId() {
+		return this.copyHttpSessionId;
+	}
+
 
 	@Override
 	public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response,
@@ -72,6 +99,9 @@ public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse res
 						attributes.put(name, session.getAttribute(name));
 					}
 				}
+				if (isCopyHttpSessionId()) {
+					attributes.put(HTTP_SESSION_ID_ATTR_NAME, session.getId());
+				}
 			}
 		}
 		return true;

spring-websocket/src/test/java/org/springframework/web/socket/server/support/HttpSessionHandshakeInterceptorTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * 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.
@@ -23,6 +23,7 @@
 
 import org.junit.Test;
 import org.mockito.Mockito;
+import org.springframework.mock.web.test.MockHttpSession;
 import org.springframework.web.socket.AbstractHttpRequestTests;
 import org.springframework.web.socket.WebSocketHandler;
 
@@ -46,7 +47,7 @@ public void copyAllAttributes() throws Exception {
 		this.servletRequest.getSession().setAttribute("bar", "baz");
 
 		HttpSessionHandshakeInterceptor interceptor = new HttpSessionHandshakeInterceptor();
-		interceptor.beforeHandshake(request, response, wsHandler, attributes);
+		interceptor.beforeHandshake(this.request, this.response, wsHandler, attributes);
 
 		assertEquals(2, attributes.size());
 		assertEquals("bar", attributes.get("foo"));
@@ -64,20 +65,36 @@ public void copySelectedAttributes() throws Exception {
 
 		Set<String> names = Collections.singleton("foo");
 		HttpSessionHandshakeInterceptor interceptor = new HttpSessionHandshakeInterceptor(names);
-		interceptor.beforeHandshake(request, response, wsHandler, attributes);
+		interceptor.beforeHandshake(this.request, this.response, wsHandler, attributes);
 
 		assertEquals(1, attributes.size());
 		assertEquals("bar", attributes.get("foo"));
 	}
 
+	@Test
+	public void copyHttpSessionId() throws Exception {
+
+		Map<String, Object> attributes = new HashMap<String, Object>();
+		WebSocketHandler wsHandler = Mockito.mock(WebSocketHandler.class);
+
+		this.servletRequest.setSession(new MockHttpSession(null, "foo"));
+
+		HttpSessionHandshakeInterceptor interceptor = new HttpSessionHandshakeInterceptor();
+		interceptor.setCopyHttpSessionId(true);
+		interceptor.beforeHandshake(this.request, this.response, wsHandler, attributes);
+
+		assertEquals(1, attributes.size());
+		assertEquals("foo", attributes.get(HttpSessionHandshakeInterceptor.HTTP_SESSION_ID_ATTR_NAME));
+	}
+
 	@Test
 	public void doNotCauseSessionCreation() throws Exception {
 
 		Map<String, Object> attributes = new HashMap<String, Object>();
 		WebSocketHandler wsHandler = Mockito.mock(WebSocketHandler.class);
 
 		HttpSessionHandshakeInterceptor interceptor = new HttpSessionHandshakeInterceptor();
-		interceptor.beforeHandshake(request, response, wsHandler, attributes);
+		interceptor.beforeHandshake(this.request, this.response, wsHandler, attributes);
 
 		assertNull(this.servletRequest.getSession(false));
 	}