Merge pull request #1682 from YangSiJun528

* pr/1682:
  Polish "Add support for YAML configuration file format"
  Add support for YAML configuration file format

Closes gh-1682

Author: mhalbritter

initializr-actuator/src/main/java/io/spring/initializr/actuate/stat/ProjectRequestDocument.java

@@ -48,6 +48,8 @@ public class ProjectRequestDocument {
 
 	private String language;
 
+	private String configurationFileFormat;
+
 	private String packaging;
 
 	private String packageName;
@@ -116,6 +118,14 @@ public void setLanguage(String language) {
 		this.language = language;
 	}
 
+	public String getConfigurationFileFormat() {
+		return this.configurationFileFormat;
+	}
+
+	public void setConfigurationFileFormat(String configurationFileFormat) {
+		this.configurationFileFormat = configurationFileFormat;
+	}
+
 	public String getPackaging() {
 		return this.packaging;
 	}
@@ -177,6 +187,7 @@ public String toString() {
 			.add("artifactId='" + this.artifactId + "'")
 			.add("javaVersion='" + this.javaVersion + "'")
 			.add("language='" + this.language + "'")
+			.add("configurationFileFormat='" + this.configurationFileFormat + "'")
 			.add("packaging='" + this.packaging + "'")
 			.add("packageName='" + this.packageName + "'")
 			.add("version=" + this.version)
@@ -331,6 +342,8 @@ public static class ErrorStateInformation {
 
 		private Boolean language;
 
+		private Boolean configurationFileFormat;
+
 		private Boolean packaging;
 
 		private Boolean type;
@@ -359,6 +372,14 @@ public void setLanguage(Boolean language) {
 			this.language = language;
 		}
 
+		public Boolean getConfigurationFileFormat() {
+			return this.configurationFileFormat;
+		}
+
+		public void setConfigurationFileFormat(Boolean configurationFileFormat) {
+			this.configurationFileFormat = configurationFileFormat;
+		}
+
 		public Boolean getPackaging() {
 			return this.packaging;
 		}
@@ -396,6 +417,7 @@ public String toString() {
 			return new StringJoiner(", ", "{", "}").add("invalid=" + this.invalid)
 				.add("javaVersion=" + this.javaVersion)
 				.add("language=" + this.language)
+				.add("configurationFileFormat=" + this.configurationFileFormat)
 				.add("packaging=" + this.packaging)
 				.add("type=" + this.type)
 				.add("dependencies=" + this.dependencies)

initializr-actuator/src/main/java/io/spring/initializr/actuate/stat/ProjectRequestDocumentFactory.java

@@ -68,6 +68,12 @@ public ProjectRequestDocument createDocument(ProjectRequestEvent event) {
 			document.triggerError().setLanguage(true);
 		}
 
+		document.setConfigurationFileFormat(request.getConfigurationFileFormat());
+		if (StringUtils.hasText(request.getConfigurationFileFormat())
+				&& metadata.getConfigurationFileFormats().get(request.getConfigurationFileFormat()) == null) {
+			document.triggerError().setConfigurationFileFormat(true);
+		}
+
 		document.setPackaging(request.getPackaging());
 		if (StringUtils.hasText(request.getPackaging())
 				&& metadata.getPackagings().get(request.getPackaging()) == null) {

initializr-actuator/src/test/resources/stat/request-invalid-dependencies.json

@@ -6,6 +6,7 @@
   "artifactId": "test",
   "javaVersion": "1.8",
   "language": "java",
+  "configurationFileFormat": "properties",
   "packaging": "jar",
   "packageName": "com.example.acme.test",
   "version": {

initializr-actuator/src/test/resources/stat/request-invalid-java-version.json

@@ -6,6 +6,7 @@
   "artifactId": "test",
   "javaVersion": "1.2",
   "language": "java",
+  "configurationFileFormat": "properties",
   "packaging": "jar",
   "packageName": "com.example.acme.test",
   "version": {

initializr-actuator/src/test/resources/stat/request-invalid-language.json

@@ -6,6 +6,7 @@
   "artifactId": "test",
   "javaVersion": "1.8",
   "language": "c",
+  "configurationFileFormat": "properties",
   "packaging": "jar",
   "packageName": "com.example.acme.test",
   "version": {

initializr-actuator/src/test/resources/stat/request-invalid-type.json

@@ -5,6 +5,7 @@
   "artifactId": "test",
   "javaVersion": "1.8",
   "language": "java",
+  "configurationFileFormat": "properties",
   "packaging": "jar",
   "packageName": "com.example.acme.test",
   "version": {

initializr-actuator/src/test/resources/stat/request-no-client.json

@@ -6,6 +6,7 @@
   "artifactId": "test",
   "javaVersion": "1.8",
   "language": "java",
+  "configurationFileFormat": "properties",
   "packaging": "jar",
   "packageName": "com.example.acme.test",
   "version": {

initializr-actuator/src/test/resources/stat/request-simple.json

@@ -6,6 +6,7 @@
   "artifactId": "project",
   "javaVersion": "1.8",
   "language": "java",
+  "configurationFileFormat": "properties",
   "packaging": "jar",
   "packageName": "com.example.acme.project",
   "version": {

initializr-docs/src/main/asciidoc/configuration-guide.adoc

@@ -286,7 +286,7 @@ will have values. In the rest of this section, we will configure those basic set
 Most of the settings are configured via `application.properties` using the `initializr`
 namespace. Because the configuration is highly hierarchical, we recommend using the yaml
 format that is more readable for such structure. If you agree, go ahead and create an
-`application.yml` in `src/main/resources`.
+`application.yaml` in `src/main/resources`.
 ====
 
 

initializr-generator-spring/src/main/java/io/spring/initializr/generator/spring/properties/ApplicationProperties.java

@@ -29,6 +29,8 @@
  */
 public class ApplicationProperties {
 
+	private static final String YAML_SPACE = "  ";
+
 	private final Map<String, Object> properties = new HashMap<>();
 
 	/**
@@ -67,12 +69,58 @@ public void add(String key, String value) {
 		add(key, (Object) value);
 	}
 
-	void writeTo(PrintWriter writer) {
+	void writeProperties(PrintWriter writer) {
 		for (Map.Entry<String, Object> entry : this.properties.entrySet()) {
 			writer.printf("%s=%s%n", entry.getKey(), entry.getValue());
 		}
 	}
 
+	void writeYaml(PrintWriter writer) {
+		Map<String, Object> nested = flattenToNestedMap(this.properties);
+		writeYamlRecursive(nested, writer, 0);
+	}
+
+	private static Map<String, Object> flattenToNestedMap(Map<String, Object> flatMap) {
+		Map<String, Object> nested = new HashMap<>();
+		flatMap.forEach((key, value) -> {
+			String[] path = parseKeyPath(key);
+			insertValueAtPath(nested, path, value);
+		});
+		return nested;
+	}
+
+	private static String[] parseKeyPath(String key) {
+		return key.split("\\.");
+	}
+
+	@SuppressWarnings("unchecked")
+	private static void insertValueAtPath(Map<String, Object> map, String[] path, Object value) {
+		Map<String, Object> current = map;
+		for (int i = 0; i < path.length - 1; i++) {
+			String segment = path[i];
+			current = (Map<String, Object>) current.computeIfAbsent(segment, (k) -> new HashMap<>());
+		}
+		current.put(path[path.length - 1], value);
+	}
+
+	private static void writeYamlRecursive(Map<String, Object> map, PrintWriter writer, int indent) {
+		map.entrySet().forEach((entry) -> writeEntry(entry, writer, indent));
+	}
+
+	@SuppressWarnings("unchecked")
+	private static void writeEntry(Map.Entry<String, Object> entry, PrintWriter writer, int indent) {
+		String indentStr = YAML_SPACE.repeat(indent);
+		Object value = entry.getValue();
+
+		if (value instanceof Map<?, ?> nestedMap) {
+			writer.printf("%s%s:%n", indentStr, entry.getKey());
+			writeYamlRecursive((Map<String, Object>) nestedMap, writer, indent + 1);
+		}
+		else {
+			writer.printf("%s%s: %s%n", indentStr, entry.getKey(), value);
+		}
+	}
+
 	private void add(String key, Object value) {
 		Assert.state(!this.properties.containsKey(key), () -> "Property '%s' already exists".formatted(key));
 		this.properties.put(key, value);