Add getContextPath to ServerHttpRequest

Issue: SPR-14726

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

@@ -25,10 +25,26 @@ import org.springframework.util.MultiValueMap;
  * Represents a reactive server-side HTTP request
  *
  * @author Arjen Poutsma
+ * @author Rossen Stoyanchev
  * @since 5.0
  */
 public interface ServerHttpRequest extends HttpRequest, ReactiveHttpInputMessage {
 
+
+	// TODO: https://jira.spring.io/browse/SPR-14726
+
+	/**
+	 * Returns the portion of the URL path that represents the context path for
+	 * the current {@link HttpHandler}. The context path is always at the
+	 * beginning of the request path. It starts with "/" but but does not end
+	 * with "/". This method may return an empty string if no context path is
+	 * configured.
+	 * @return the context path (not decoded) or an empty string
+	 */
+	default String getContextPath() {
+		return "";
+	}
+
 	/**
 	 * Return a read-only map with parsed and decoded query parameter values.
 	 */

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

@@ -81,6 +81,11 @@ public class ServletServerHttpRequest extends AbstractServerHttpRequest {
 		return HttpMethod.valueOf(getServletRequest().getMethod());
 	}
 
+	@Override
+	public String getContextPath() {
+		return getServletRequest().getContextPath();
+	}
+
 	@Override
 	protected URI initUri() throws URISyntaxException {
 		StringBuffer url = this.request.getRequestURL();

spring-web/src/main/java/org/springframework/web/util/HttpRequestPathHelper.java

@@ -19,8 +19,10 @@ import java.io.UnsupportedEncodingException;
 import java.util.LinkedHashMap;
 import java.util.Map;
 
+import org.springframework.http.server.reactive.ServerHttpRequest;
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
+import org.springframework.util.StringUtils;
 import org.springframework.web.server.ServerWebExchange;
 
 /**
@@ -54,10 +56,19 @@ public class HttpRequestPathHelper {
 
 
 	public String getLookupPathForRequest(ServerWebExchange exchange) {
-		String path = exchange.getRequest().getURI().getRawPath();
+		String path = getPathWithinApplication(exchange.getRequest());
 		return (this.shouldUrlDecode() ? decode(exchange, path) : path);
 	}
 
+	private String getPathWithinApplication(ServerHttpRequest request) {
+		String contextPath = request.getContextPath();
+		String path = request.getURI().getRawPath();
+		if (!StringUtils.hasText(contextPath)) {
+			return path;
+		}
+		return (path.length() > contextPath.length() ? path.substring(contextPath.length()) : "");
+	}
+
 	private String decode(ServerWebExchange exchange, String path) {
 		// TODO: look up request encoding?
 		try {