Avoid one layer of HttpHeaders wrapping

See gh-24680

spring-web/src/main/java/org/springframework/http/HttpEntity.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -99,11 +99,7 @@ public class HttpEntity<T> {
 	 */
 	public HttpEntity(@Nullable T body, @Nullable MultiValueMap<String, String> headers) {
 		this.body = body;
-		HttpHeaders tempHeaders = new HttpHeaders();
-		if (headers != null) {
-			tempHeaders.putAll(headers);
-		}
-		this.headers = HttpHeaders.readOnlyHttpHeaders(tempHeaders);
+		this.headers = HttpHeaders.readOnlyHttpHeaders(headers != null ? headers : new HttpHeaders());
 	}
 
 

spring-web/src/main/java/org/springframework/http/server/reactive/AbstractServerHttpRequest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -76,7 +76,7 @@ public abstract class AbstractServerHttpRequest implements ServerHttpRequest {
 	 * @param contextPath the context path for the request
 	 * @param headers the headers for the request
 	 */
-	public AbstractServerHttpRequest(URI uri, @Nullable String contextPath, HttpHeaders headers) {
+	public AbstractServerHttpRequest(URI uri, @Nullable String contextPath, MultiValueMap<String, String> headers) {
 		this.uri = uri;
 		this.path = RequestPath.parse(uri, contextPath);
 		this.headers = HttpHeaders.readOnlyHttpHeaders(headers);

spring-web/src/main/java/org/springframework/http/server/reactive/JettyHttpHandlerAdapter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -36,6 +36,7 @@ import org.springframework.core.io.buffer.DataBufferFactory;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.MediaType;
 import org.springframework.util.Assert;
+import org.springframework.util.MultiValueMap;
 
 /**
  * {@link ServletHttpHandlerAdapter} extension that uses Jetty APIs for writing
@@ -79,9 +80,9 @@ public class JettyHttpHandlerAdapter extends ServletHttpHandlerAdapter {
 			super(createHeaders(request), request, asyncContext, servletPath, bufferFactory, bufferSize);
 		}
 
-		private static HttpHeaders createHeaders(HttpServletRequest request) {
+		private static MultiValueMap<String, String> createHeaders(HttpServletRequest request) {
 			HttpFields fields = ((Request) request).getMetaData().getFields();
-			return new HttpHeaders(new JettyHeadersAdapter(fields));
+			return new JettyHeadersAdapter(fields);
 		}
 	}
 

spring-web/src/main/java/org/springframework/http/server/reactive/ReactorServerHttpRequest.java

@@ -33,7 +33,6 @@ import reactor.netty.http.server.HttpServerRequest;
 import org.springframework.core.io.buffer.DataBuffer;
 import org.springframework.core.io.buffer.NettyDataBufferFactory;
 import org.springframework.http.HttpCookie;
-import org.springframework.http.HttpHeaders;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.LinkedMultiValueMap;
@@ -59,7 +58,7 @@ class ReactorServerHttpRequest extends AbstractServerHttpRequest {
 	public ReactorServerHttpRequest(HttpServerRequest request, NettyDataBufferFactory bufferFactory)
 			throws URISyntaxException {
 
-		super(initUri(request), "", initHeaders(request));
+		super(initUri(request), "", new NettyHeadersAdapter(request.requestHeaders()));
 		Assert.notNull(bufferFactory, "DataBufferFactory must not be null");
 		this.request = request;
 		this.bufferFactory = bufferFactory;
@@ -127,11 +126,6 @@ class ReactorServerHttpRequest extends AbstractServerHttpRequest {
 		return uri;
 	}
 
-	private static HttpHeaders initHeaders(HttpServerRequest channel) {
-		NettyHeadersAdapter headersMap = new NettyHeadersAdapter(channel.requestHeaders());
-		return new HttpHeaders(headersMap);
-	}
-
 
 	@Override
 	public String getMethodValue() {

spring-web/src/main/java/org/springframework/http/server/reactive/ServletServerHttpRequest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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 java.net.URISyntaxException;
 import java.nio.charset.Charset;
 import java.security.cert.X509Certificate;
 import java.util.Enumeration;
+import java.util.Locale;
 import java.util.Map;
 
 import javax.servlet.AsyncContext;
@@ -44,6 +45,7 @@ import org.springframework.http.HttpHeaders;
 import org.springframework.http.MediaType;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
+import org.springframework.util.CollectionUtils;
 import org.springframework.util.LinkedCaseInsensitiveMap;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
@@ -77,8 +79,8 @@ class ServletServerHttpRequest extends AbstractServerHttpRequest {
 		this(createDefaultHttpHeaders(request), request, asyncContext, servletPath, bufferFactory, bufferSize);
 	}
 
-	public ServletServerHttpRequest(HttpHeaders headers, HttpServletRequest request, AsyncContext asyncContext,
-			String servletPath, DataBufferFactory bufferFactory, int bufferSize)
+	public ServletServerHttpRequest(MultiValueMap<String, String> headers, HttpServletRequest request,
+			AsyncContext asyncContext, String servletPath, DataBufferFactory bufferFactory, int bufferSize)
 			throws IOException, URISyntaxException {
 
 		super(initUri(request), request.getContextPath() + servletPath, initHeaders(headers, request));
@@ -99,8 +101,9 @@ class ServletServerHttpRequest extends AbstractServerHttpRequest {
 	}
 
 
-	private static HttpHeaders createDefaultHttpHeaders(HttpServletRequest request) {
-		HttpHeaders headers = new HttpHeaders();
+	private static MultiValueMap<String, String> createDefaultHttpHeaders(HttpServletRequest request) {
+		MultiValueMap<String, String> headers =
+				CollectionUtils.toMultiValueMap(new LinkedCaseInsensitiveMap<>(8, Locale.ENGLISH));
 		for (Enumeration<?> names = request.getHeaderNames(); names.hasMoreElements(); ) {
 			String name = (String) names.nextElement();
 			for (Enumeration<?> values = request.getHeaders(name); values.hasMoreElements(); ) {
@@ -120,34 +123,36 @@ class ServletServerHttpRequest extends AbstractServerHttpRequest {
 		return new URI(url.toString());
 	}
 
-	private static HttpHeaders initHeaders(HttpHeaders headers, HttpServletRequest request) {
-		MediaType contentType = headers.getContentType();
-		if (contentType == null) {
+	private static MultiValueMap<String, String> initHeaders(
+			MultiValueMap<String, String> headerValues, HttpServletRequest request) {
+
+		HttpHeaders headers = null;
+		MediaType contentType = null;
+		if (!StringUtils.hasLength(headerValues.getFirst(HttpHeaders.CONTENT_TYPE))) {
 			String requestContentType = request.getContentType();
 			if (StringUtils.hasLength(requestContentType)) {
 				contentType = MediaType.parseMediaType(requestContentType);
+				headers = new HttpHeaders(headerValues);
 				headers.setContentType(contentType);
 			}
 		}
 		if (contentType != null && contentType.getCharset() == null) {
 			String encoding = request.getCharacterEncoding();
 			if (StringUtils.hasLength(encoding)) {
-				Charset charset = Charset.forName(encoding);
 				Map<String, String> params = new LinkedCaseInsensitiveMap<>();
 				params.putAll(contentType.getParameters());
-				params.put("charset", charset.toString());
-				headers.setContentType(
-						new MediaType(contentType.getType(), contentType.getSubtype(),
-								params));
+				params.put("charset", Charset.forName(encoding).toString());
+				headers.setContentType(new MediaType(contentType, params));
 			}
 		}
-		if (headers.getContentLength() == -1) {
+		if (headerValues.getFirst(HttpHeaders.CONTENT_TYPE) == null) {
 			int contentLength = request.getContentLength();
 			if (contentLength != -1) {
+				headers = (headers != null ? headers : new HttpHeaders(headerValues));
 				headers.setContentLength(contentLength);
 			}
 		}
-		return headers;
+		return (headers != null ? headers : headerValues);
 	}
 
 

spring-web/src/main/java/org/springframework/http/server/reactive/TomcatHttpHandlerAdapter.java

@@ -44,6 +44,7 @@ import org.springframework.core.io.buffer.DataBufferUtils;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.MediaType;
 import org.springframework.util.Assert;
+import org.springframework.util.MultiValueMap;
 import org.springframework.util.ReflectionUtils;
 
 /**
@@ -105,14 +106,13 @@ public class TomcatHttpHandlerAdapter extends ServletHttpHandlerAdapter {
 			this.bufferSize = bufferSize;
 		}
 
-		private static HttpHeaders createTomcatHttpHeaders(HttpServletRequest request) {
+		private static MultiValueMap<String, String> createTomcatHttpHeaders(HttpServletRequest request) {
 			RequestFacade requestFacade = getRequestFacade(request);
 			org.apache.catalina.connector.Request connectorRequest = (org.apache.catalina.connector.Request)
 					ReflectionUtils.getField(COYOTE_REQUEST_FIELD, requestFacade);
 			Assert.state(connectorRequest != null, "No Tomcat connector request");
 			Request tomcatRequest = connectorRequest.getCoyoteRequest();
-			TomcatHeadersAdapter headers = new TomcatHeadersAdapter(tomcatRequest.getMimeHeaders());
-			return new HttpHeaders(headers);
+			return new TomcatHeadersAdapter(tomcatRequest.getMimeHeaders());
 		}
 
 		private static RequestFacade getRequestFacade(HttpServletRequest request) {

spring-web/src/main/java/org/springframework/http/server/reactive/UndertowServerHttpRequest.java

@@ -38,7 +38,6 @@ import org.springframework.core.io.buffer.DataBufferUtils;
 import org.springframework.core.io.buffer.DataBufferWrapper;
 import org.springframework.core.io.buffer.PooledDataBuffer;
 import org.springframework.http.HttpCookie;
-import org.springframework.http.HttpHeaders;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.LinkedMultiValueMap;
@@ -63,7 +62,7 @@ class UndertowServerHttpRequest extends AbstractServerHttpRequest {
 	public UndertowServerHttpRequest(HttpServerExchange exchange, DataBufferFactory bufferFactory)
 			throws URISyntaxException {
 
-		super(initUri(exchange), "", initHeaders(exchange));
+		super(initUri(exchange), "", new UndertowHeadersAdapter(exchange.getRequestHeaders()));
 		this.exchange = exchange;
 		this.body = new RequestBodyPublisher(exchange, bufferFactory);
 		this.body.registerListeners(exchange);
@@ -77,10 +76,6 @@ class UndertowServerHttpRequest extends AbstractServerHttpRequest {
 		return new URI(requestUriAndQuery);
 	}
 
-	private static HttpHeaders initHeaders(HttpServerExchange exchange) {
-		return new HttpHeaders(new UndertowHeadersAdapter(exchange.getRequestHeaders()));
-	}
-
 	@Override
 	public String getMethodValue() {
 		return this.exchange.getRequestMethod().toString();

spring-webflux/src/main/java/org/springframework/web/reactive/result/view/DefaultRendering.java

@@ -32,7 +32,7 @@ import org.springframework.ui.Model;
  */
 class DefaultRendering implements Rendering {
 
-	private static final HttpHeaders EMPTY_HEADERS = HttpHeaders.readOnlyHttpHeaders(new HttpHeaders());
+	private static final HttpHeaders EMPTY_HEADERS = HttpHeaders.EMPTY;
 
 
 	private final Object view;