AsyncRestTemplate triggers no-output HTTP requests immediately as well

Issue: SPR-14093

Author: jhoeller

spring-web/src/main/java/org/springframework/http/client/SimpleBufferingAsyncClientHttpRequest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -89,6 +89,10 @@ public ClientHttpResponse call() throws Exception {
 				if (connection.getDoOutput()) {
 					FileCopyUtils.copy(bufferedOutput, connection.getOutputStream());
 				}
+				else {
+					// Immediately trigger the request in a no-output scenario as well
+					connection.getResponseCode();
+				}
 				return new SimpleClientHttpResponse(connection);
 			}
 		});

spring-web/src/main/java/org/springframework/http/client/SimpleBufferingClientHttpRequest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -68,20 +68,21 @@ public URI getURI() {
 	@Override
 	protected ClientHttpResponse executeInternal(HttpHeaders headers, byte[] bufferedOutput) throws IOException {
 		addHeaders(this.connection, headers);
-
 		// JDK <1.8 doesn't support getOutputStream with HTTP DELETE
 		if (HttpMethod.DELETE == getMethod() && bufferedOutput.length == 0) {
 			this.connection.setDoOutput(false);
 		}
-
 		if (this.connection.getDoOutput() && this.outputStreaming) {
 			this.connection.setFixedLengthStreamingMode(bufferedOutput.length);
 		}
 		this.connection.connect();
 		if (this.connection.getDoOutput()) {
 			FileCopyUtils.copy(bufferedOutput, this.connection.getOutputStream());
 		}
-
+		else {
+			// Immediately trigger the request in a no-output scenario as well
+			this.connection.getResponseCode();
+		}
 		return new SimpleClientHttpResponse(this.connection);
 	}
 

spring-web/src/main/java/org/springframework/http/client/SimpleStreamingAsyncClientHttpRequest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -108,6 +108,8 @@ public ClientHttpResponse call() throws Exception {
 					else {
 						SimpleBufferingClientHttpRequest.addHeaders(connection, headers);
 						connection.connect();
+						// Immediately trigger the request in a no-output scenario as well
+						connection.getResponseCode();
 					}
 				}
 				catch (IOException ex) {

spring-web/src/main/java/org/springframework/http/client/SimpleStreamingClientHttpRequest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -94,6 +94,8 @@ protected ClientHttpResponse executeInternal(HttpHeaders headers) throws IOExcep
 			else {
 				SimpleBufferingClientHttpRequest.addHeaders(this.connection, headers);
 				this.connection.connect();
+				// Immediately trigger the request in a no-output scenario as well
+				this.connection.getResponseCode();
 			}
 		}
 		catch (IOException ex) {

spring-web/src/test/java/org/springframework/http/client/BufferedSimpleHttpRequestFactoryTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 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.
@@ -16,16 +16,19 @@
 
 package org.springframework.http.client;
 
-import static org.junit.Assert.assertEquals;
-
+import java.io.ByteArrayInputStream;
 import java.io.IOException;
+import java.io.InputStream;
 import java.net.HttpURLConnection;
 import java.net.ProtocolException;
 import java.net.URL;
 
 import org.junit.Test;
+
 import org.springframework.http.HttpMethod;
 
+import static org.junit.Assert.*;
+
 public class BufferedSimpleHttpRequestFactoryTests extends AbstractHttpRequestFactoryTestCase {
 
 	@Override
@@ -89,5 +92,11 @@ public void disconnect() {
 		public boolean usingProxy() {
 			return false;
 		}
+
+		@Override
+		public InputStream getInputStream() throws IOException {
+			return new ByteArrayInputStream(new byte[0]);
+		}
 	}
+
 }