fixed ServletServerHttpRequest to reconstruct from "request.getParameterMap()" for form POST only (SPR-8688)

org.springframework.web/src/main/java/org/springframework/http/server/ServletServerHttpRequest.java

@@ -44,13 +44,11 @@ import org.springframework.util.Assert;
  */
 public class ServletServerHttpRequest implements ServerHttpRequest {
 
-	private static final String FORM_CONTENT_TYPE = "application/x-www-form-urlencoded";
+	protected static final String FORM_CONTENT_TYPE = "application/x-www-form-urlencoded";
 
-	private static final String POST_METHOD = "POST";
+	protected static final String FORM_CHARSET = "UTF-8";
 
-	private static final String PUT_METHOD = "PUT";
-
-	private static final String FORM_CHARSET = "UTF-8";
+	private static final String METHOD_POST = "POST";
 
 	private final HttpServletRequest servletRequest;
 
@@ -105,20 +103,26 @@ public class ServletServerHttpRequest implements ServerHttpRequest {
 	}
 
 	public InputStream getBody() throws IOException {
-		if (isFormSubmittal(this.servletRequest)) {
-			return getFormBody(this.servletRequest);
+		if (isFormPost(this.servletRequest)) {
+			return getBodyFromServletRequestParameters(this.servletRequest);
 		}
 		else {
 			return this.servletRequest.getInputStream();
 		}
 	}
 
-	private boolean isFormSubmittal(HttpServletRequest request) {
-		return FORM_CONTENT_TYPE.equals(request.getContentType()) &&
-				(POST_METHOD.equalsIgnoreCase(request.getMethod()) || PUT_METHOD.equalsIgnoreCase(request.getMethod()));
+	private boolean isFormPost(HttpServletRequest request) {
+		return (request.getContentType() != null && request.getContentType().contains(FORM_CONTENT_TYPE) &&
+				METHOD_POST.equalsIgnoreCase(request.getMethod()));
 	}
 
-	private InputStream getFormBody(HttpServletRequest request) throws IOException {
+	/**
+	 * Use {@link javax.servlet.ServletRequest#getParameterMap()} to reconstruct the
+	 * body of a form 'POST' providing a predictable outcome as opposed to reading
+	 * from the body, which can fail if any other code has used ServletRequest
+	 * to access a parameter thus causing the input stream to be "consumed".
+	 */
+	private InputStream getBodyFromServletRequestParameters(HttpServletRequest request) throws IOException {
 		ByteArrayOutputStream bos = new ByteArrayOutputStream();
 		Writer writer = new OutputStreamWriter(bos, FORM_CHARSET);