refactor: optimize performance.

Signed-off-by: Haotian Zhang <928016560@qq.com>

spring-cloud-starter-tencent-metadata-transfer/src/main/java/com/tencent/cloud/metadata/core/TransHeadersTransfer.java

@@ -53,15 +53,17 @@ public final class TransHeadersTransfer {
 		Map<String, String> transHeaderMetadata = MetadataContextHolder.get().getTransHeaders();
 		if (!CollectionUtils.isEmpty(transHeaderMetadata)) {
 			String transHeaders = transHeaderMetadata.keySet().iterator().next();
-			String[] transHeaderArray = transHeaders.split(",");
-			Enumeration<String> httpHeaders = httpServletRequest.getHeaderNames();
-			while (httpHeaders.hasMoreElements()) {
-				String httpHeader = httpHeaders.nextElement();
-				for (String transHeader : transHeaderArray) {
-					if (transHeader.equals(httpHeader)) {
-						String httpHeaderValue = httpServletRequest.getHeader(httpHeader);
-						// for example, {"trans-headers-kv" : {"header1":"v1","header2":"v2"...}}
-						MetadataContextHolder.get().setTransHeadersKV(httpHeader, httpHeaderValue);
+			if (transHeaders != null) {
+				String[] transHeaderArray = transHeaders.split(",");
+				Enumeration<String> httpHeaders = httpServletRequest.getHeaderNames();
+				while (httpHeaders.hasMoreElements()) {
+					String httpHeader = httpHeaders.nextElement();
+					for (String transHeader : transHeaderArray) {
+						if (transHeader.equals(httpHeader)) {
+							String httpHeaderValue = httpServletRequest.getHeader(httpHeader);
+							// for example, {"trans-headers-kv" : {"header1":"v1","header2":"v2"...}}
+							MetadataContextHolder.get().setTransHeadersKV(httpHeader, httpHeaderValue);
+						}
 					}
 				}
 			}
@@ -79,16 +81,18 @@ public final class TransHeadersTransfer {
 		Map<String, String> transHeaderMetadata = MetadataContextHolder.get().getTransHeaders();
 		if (!CollectionUtils.isEmpty(transHeaderMetadata)) {
 			String transHeaders = transHeaderMetadata.keySet().iterator().next();
-			String[] transHeaderArray = transHeaders.split(",");
-			HttpHeaders headers = serverHttpRequest.getHeaders();
-			Set<String> headerKeys = headers.keySet();
-			for (String httpHeader : headerKeys) {
-				for (String transHeader : transHeaderArray) {
-					if (transHeader.equals(httpHeader)) {
-						List<String> list = headers.get(httpHeader);
-						String httpHeaderValue = JacksonUtils.serialize2Json(list);
-						// for example, {"trans-headers-kv" : {"header1":"v1","header2":"v2"...}}
-						MetadataContextHolder.get().setTransHeadersKV(httpHeader, httpHeaderValue);
+			if (transHeaders != null) {
+				String[] transHeaderArray = transHeaders.split(",");
+				HttpHeaders headers = serverHttpRequest.getHeaders();
+				Set<String> headerKeys = headers.keySet();
+				for (String httpHeader : headerKeys) {
+					for (String transHeader : transHeaderArray) {
+						if (transHeader.equals(httpHeader)) {
+							List<String> list = headers.get(httpHeader);
+							String httpHeaderValue = JacksonUtils.serialize2Json(list);
+							// for example, {"trans-headers-kv" : {"header1":"v1","header2":"v2"...}}
+							MetadataContextHolder.get().setTransHeadersKV(httpHeader, httpHeaderValue);
+						}
 					}
 				}
 			}