fix: preserve Nacos config file extension across refresh

spring-cloud-alibaba-starters/spring-alibaba-nacos-config/src/main/java/com/alibaba/cloud/nacos/client/NacosPropertySource.java

@@ -24,6 +24,7 @@
 import java.util.Map;
 
 import com.alibaba.cloud.nacos.NacosConfigProperties;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.core.env.MapPropertySource;
 import org.springframework.core.env.PropertySource;
@@ -55,19 +56,43 @@ public class NacosPropertySource extends MapPropertySource {
 	 */
 	private final boolean isRefreshable;
 
+	/**
+	 * File extension this property source was parsed with (e.g. {@code yaml},
+	 * {@code properties}, {@code json}). Captured so that subsequent refreshes
+	 * can re-parse updated config with the same loader instead of falling back
+	 * to the properties default. The value is the same notion the rest of the
+	 * codebase tracks as {@code NacosConfigProperties#fileExtension} and
+	 * {@code NacosItemConfig#suffix}.
+	 */
+	private final @Nullable String fileExtension;
+
 	NacosPropertySource(String group, String dataId, Map<String, Object> source,
 			Date timestamp, boolean isRefreshable) {
+		this(group, dataId, source, timestamp, isRefreshable, null);
+	}
+
+	private NacosPropertySource(String group, String dataId, Map<String, Object> source,
+			Date timestamp, boolean isRefreshable,
+			@Nullable String fileExtension) {
 		super(String.join(NacosConfigProperties.COMMAS, dataId, group), source);
 		this.group = group;
 		this.dataId = dataId;
 		this.timestamp = timestamp;
 		this.isRefreshable = isRefreshable;
+		this.fileExtension = fileExtension;
 	}
 
 	public NacosPropertySource(List<PropertySource<?>> propertySources, String group,
 			String dataId, Date timestamp, boolean isRefreshable) {
 		this(group, dataId, getSourceMap(group, dataId, propertySources), timestamp,
-				isRefreshable);
+				isRefreshable, null);
+	}
+
+	public NacosPropertySource(List<PropertySource<?>> propertySources, String group,
+			String dataId, Date timestamp, boolean isRefreshable,
+			@Nullable String fileExtension) {
+		this(group, dataId, getSourceMap(group, dataId, propertySources), timestamp,
+				isRefreshable, fileExtension);
 	}
 
 	private static Map<String, Object> getSourceMap(String group, String dataId,
@@ -130,4 +155,14 @@ public boolean isRefreshable() {
 		return isRefreshable;
 	}
 
+	/**
+	 * Returns the file extension this property source was parsed with, or
+	 * {@code null} if it was built through a constructor that does not carry
+	 * the extension. Used internally by the refresh listener to re-parse
+	 * pushed Nacos content with the original format.
+	 */
+	public @Nullable String getFileExtension() {
+		return fileExtension;
+	}
+
 }

spring-cloud-alibaba-starters/spring-alibaba-nacos-config/src/main/java/com/alibaba/cloud/nacos/client/NacosPropertySourceBuilder.java

@@ -75,7 +75,7 @@ public NacosPropertySource build(String dataId, String group, String fileExtensi
 		List<PropertySource<?>> propertySources = loadNacosData(dataId, group,
 				fileExtension);
 		NacosPropertySource nacosPropertySource = new NacosPropertySource(propertySources,
-				group, dataId, new Date(), isRefreshable);
+				group, dataId, new Date(), isRefreshable, fileExtension);
 		NacosPropertySourceRepository.collectNacosPropertySource(nacosPropertySource);
 		return nacosPropertySource;
 	}

spring-cloud-alibaba-starters/spring-alibaba-nacos-config/src/main/java/com/alibaba/cloud/nacos/configdata/NacosConfigDataLoader.java

@@ -92,7 +92,7 @@ public NacosConfigDataLoader(DeferredLogFactory logFactory) {
 
 			NacosPropertySource propertySource = new NacosPropertySource(propertySources,
 					config.getGroup(), config.getDataId(), new Date(),
-					config.isRefreshEnabled());
+					config.isRefreshEnabled(), config.getSuffix());
 
 			NacosPropertySourceRepository.collectNacosPropertySource(propertySource);
 

spring-cloud-alibaba-starters/spring-alibaba-nacos-config/src/main/java/com/alibaba/cloud/nacos/refresh/NacosPropertySourceRefreshListener.java

@@ -40,6 +40,7 @@
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.env.MutablePropertySources;
 import org.springframework.core.env.PropertySource;
+import org.springframework.util.StringUtils;
 
 public class NacosPropertySourceRefreshListener implements BeanPostProcessor, SmartApplicationListener, ApplicationContextAware {
 
@@ -114,9 +115,25 @@ public void handle(NacosConfigRefreshEvent event) {
 						log.warn("Event dataId or group is null, skipping refresh");
 						return;
 					}
-					NacosPropertySource newProperSource = nacosPropertySourceBuilder.build(dataId, group, "properties", ((NacosPropertySource) prevpropertySource).isRefreshable());
+					NacosPropertySource prevNacosPropertySource = (NacosPropertySource) prevpropertySource;
+					String fileExtension = prevNacosPropertySource.getFileExtension();
+					if (!StringUtils.hasText(fileExtension)) {
+						// The source was built through the legacy constructor (e.g. by
+						// third-party code) and did not record its format. We cannot
+						// safely guess the extension from global configuration here,
+						// because shared-configs / extension-configs may declare their
+						// own suffix per entry. Fall back to "properties" — the
+						// historical default — and log so the case is diagnosable.
+						log.warn(
+								"Previous Nacos property source did not record a file extension,"
+										+ " falling back to 'properties'; non-properties formats"
+										+ " may be mis-parsed. sourceName={}", sourceName);
+						fileExtension = "properties";
+					}
+					NacosPropertySource newProperSource = nacosPropertySourceBuilder.build(dataId, group, fileExtension, prevNacosPropertySource.isRefreshable());
 					target.replace(sourceName, newProperSource);
-					log.info("Replace Nacos Property Source : " + sourceName);
+					log.info("Replace Nacos Property Source: {} (fileExtension={})",
+							sourceName, fileExtension);
 				}
 
 			}

spring-cloud-alibaba-starters/spring-alibaba-nacos-config/src/test/java/com/alibaba/cloud/nacos/client/NacosPropertySourceBuilderTest.java

@@ -0,0 +1,65 @@
+/*
+ * Copyright 2013-present 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.alibaba.cloud.nacos.client;
+
+import com.alibaba.nacos.api.config.ConfigService;
+import org.junit.jupiter.api.Test;
+import org.mockito.ArgumentMatchers;
+import org.mockito.Mockito;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link NacosPropertySourceBuilder}.
+ */
+public class NacosPropertySourceBuilderTest {
+
+	@Test
+	void builtPropertySourcePreservesFileExtension() throws Exception {
+		ConfigService configService = Mockito.mock(ConfigService.class);
+		Mockito.when(configService.getConfig(ArgumentMatchers.anyString(),
+				ArgumentMatchers.anyString(), ArgumentMatchers.anyLong()))
+				.thenReturn("key: value");
+		NacosPropertySourceBuilder builder = new NacosPropertySourceBuilder(configService,
+				1000L);
+
+		NacosPropertySource source = builder.build("app.yaml", "DEFAULT_GROUP", "yaml",
+				true);
+
+		assertThat(source.getFileExtension()).isEqualTo("yaml");
+		assertThat(source.getDataId()).isEqualTo("app.yaml");
+		assertThat(source.getGroup()).isEqualTo("DEFAULT_GROUP");
+		assertThat(source.isRefreshable()).isTrue();
+	}
+
+	@Test
+	void builtPropertySourcePreservesPropertiesExtension() throws Exception {
+		ConfigService configService = Mockito.mock(ConfigService.class);
+		Mockito.when(configService.getConfig(ArgumentMatchers.anyString(),
+				ArgumentMatchers.anyString(), ArgumentMatchers.anyLong()))
+				.thenReturn("key=value");
+		NacosPropertySourceBuilder builder = new NacosPropertySourceBuilder(configService,
+				1000L);
+
+		NacosPropertySource source = builder.build("app", "DEFAULT_GROUP", "properties",
+				false);
+
+		assertThat(source.getFileExtension()).isEqualTo("properties");
+		assertThat(source.isRefreshable()).isFalse();
+	}
+
+}

spring-cloud-alibaba-starters/spring-alibaba-nacos-config/src/test/java/com/alibaba/cloud/nacos/client/NacosPropertySourceTest.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2013-present 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.alibaba.cloud.nacos.client;
+
+import java.util.Collections;
+import java.util.Date;
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.core.env.PropertySource;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link NacosPropertySource}.
+ */
+public class NacosPropertySourceTest {
+
+	@Test
+	void fileExtensionIsNullWhenUsingLegacyConstructor() {
+		List<PropertySource<?>> sources = Collections.emptyList();
+		NacosPropertySource source = new NacosPropertySource(sources, "DEFAULT_GROUP",
+				"app.yaml", new Date(), true);
+		assertThat(source.getFileExtension()).isNull();
+	}
+
+	@Test
+	void fileExtensionIsPreservedWhenProvided() {
+		List<PropertySource<?>> sources = Collections.emptyList();
+		NacosPropertySource source = new NacosPropertySource(sources, "DEFAULT_GROUP",
+				"app.yaml", new Date(), true, "yaml");
+		assertThat(source.getFileExtension()).isEqualTo("yaml");
+	}
+
+	@Test
+	void fileExtensionCanBeNullExplicitly() {
+		List<PropertySource<?>> sources = Collections.emptyList();
+		NacosPropertySource source = new NacosPropertySource(sources, "DEFAULT_GROUP",
+				"app", new Date(), true, null);
+		assertThat(source.getFileExtension()).isNull();
+	}
+
+	@Test
+	void otherPropertiesAreNotAffectedByNewConstructor() {
+		Date timestamp = new Date();
+		List<PropertySource<?>> sources = Collections.emptyList();
+		NacosPropertySource source = new NacosPropertySource(sources, "MY_GROUP",
+				"app.json", timestamp, false, "json");
+		assertThat(source.getGroup()).isEqualTo("MY_GROUP");
+		assertThat(source.getDataId()).isEqualTo("app.json");
+		assertThat(source.getTimestamp()).isEqualTo(timestamp);
+		assertThat(source.isRefreshable()).isFalse();
+		assertThat(source.getFileExtension()).isEqualTo("json");
+	}
+
+}