Merge pull request #48930 from jdsalasca

* gh-48930:
  Polish "Provide support for adding to the mime types that are compressed"
  Provide support for adding to the mime types that are compressed

Closes gh-48930

documentation/spring-boot-docs/src/docs/antora/modules/how-to/pages/webserver.adoc

@@ -205,7 +205,8 @@ By default, responses are compressed only if their content type is one of the fo
 * `application/json`
 * `application/xml`
 
-You can configure this behavior by setting the configprop:server.compression.mime-types[] property.
+To configure the mime types that will be compressed, replacing the defaults, set the configprop:server.compression.mime-types[] property.
+To keep the defaults and configure additional mime types, set the configprop:server.compression.additional-mime-types[] property instead.
 
 
 

module/spring-boot-jetty/src/main/java/org/springframework/boot/jetty/JettyHandlerWrappers.java

@@ -46,7 +46,7 @@ final class JettyHandlerWrappers {
 		gzip.setMinCompressSize((int) compression.getMinResponseSize().toBytes());
 		compressionHandler.putCompression(gzip);
 		Builder configBuilder = CompressionConfig.builder();
-		for (String mimeType : compression.getMimeTypes()) {
+		for (String mimeType : compression.getAllMimeTypes()) {
 			configBuilder.compressIncludeMimeType(mimeType);
 		}
 		for (HttpMethod httpMethod : HttpMethod.values()) {

module/spring-boot-reactor-netty/src/main/java/org/springframework/boot/reactor/netty/CompressionCustomizer.java

@@ -56,7 +56,7 @@ final class CompressionCustomizer implements NettyServerCustomizer {
 		if (!this.compression.getMinResponseSize().isNegative()) {
 			server = server.compress((int) this.compression.getMinResponseSize().toBytes());
 		}
-		CompressionPredicate mimeTypes = getMimeTypesPredicate(this.compression.getMimeTypes());
+		CompressionPredicate mimeTypes = getMimeTypesPredicate(this.compression.getAllMimeTypes());
 		CompressionPredicate excludedUserAgents = getExcludedUserAgentsPredicate(
 				this.compression.getExcludedUserAgents());
 		server = server.compress(mimeTypes.and(excludedUserAgents));

module/spring-boot-tomcat/src/main/java/org/springframework/boot/tomcat/CompressionConnectorCustomizer.java

@@ -63,7 +63,7 @@ public class CompressionConnectorCustomizer implements TomcatConnectorCustomizer
 	}
 
 	private String getMimeTypes(Compression compression) {
-		return StringUtils.arrayToCommaDelimitedString(compression.getMimeTypes());
+		return StringUtils.arrayToCommaDelimitedString(compression.getAllMimeTypes());
 	}
 
 	private String getExcludedUserAgents(Compression compression) {

module/spring-boot-web-server/src/main/java/org/springframework/boot/web/server/Compression.java

@@ -19,6 +19,7 @@ package org.springframework.boot.web.server;
 import org.jspecify.annotations.Nullable;
 
 import org.springframework.boot.context.properties.ConfigurationPropertiesSource;
+import org.springframework.util.StringUtils;
 import org.springframework.util.unit.DataSize;
 
 /**
@@ -43,6 +44,11 @@ public class Compression {
 	private String[] mimeTypes = new String[] { "text/html", "text/xml", "text/plain", "text/css", "text/javascript",
 			"application/javascript", "application/json", "application/xml" };
 
+	/**
+	 * Comma-separated list of additional MIME types that should be compressed.
+	 */
+	private String[] additionalMimeTypes = new String[0];
+
 	/**
 	 * Comma-separated list of user agents for which responses should not be compressed.
 	 */
@@ -77,6 +83,23 @@ public class Compression {
 		this.mimeTypes = mimeTypes;
 	}
 
+	/**
+	 * Return the MIME types that should be compressed, including any additional types.
+	 * @return the MIME types that should be compressed
+	 */
+	public String[] getAllMimeTypes() {
+		String[] combined = StringUtils.concatenateStringArrays(this.mimeTypes, this.additionalMimeTypes);
+		return (combined != null) ? combined : this.mimeTypes;
+	}
+
+	public String[] getAdditionalMimeTypes() {
+		return this.additionalMimeTypes;
+	}
+
+	public void setAdditionalMimeTypes(String[] additionalMimeTypes) {
+		this.additionalMimeTypes = additionalMimeTypes;
+	}
+
 	public String @Nullable [] getExcludedUserAgents() {
 		return this.excludedUserAgents;
 	}

module/spring-boot-web-server/src/test/java/org/springframework/boot/web/server/autoconfigure/ServerPropertiesTests.java

@@ -27,6 +27,7 @@ import org.springframework.boot.context.properties.bind.Bindable;
 import org.springframework.boot.context.properties.bind.Binder;
 import org.springframework.boot.context.properties.source.ConfigurationPropertySource;
 import org.springframework.boot.context.properties.source.MapConfigurationPropertySource;
+import org.springframework.boot.web.server.Compression;
 import org.springframework.boot.web.server.MimeMappings;
 import org.springframework.boot.web.server.MimeMappings.Mapping;
 import org.springframework.util.unit.DataSize;
@@ -148,6 +149,13 @@ class ServerPropertiesTests {
 			.isEqualTo(new Http11Nio2Protocol().getMaxHttpRequestHeaderSize());
 	}
 
+	@Test
+	void additionalCompressionMimeTypesAreAddedToDefaults() {
+		bind("server.compression.additional-mime-types", "application/zip");
+		assertThat(this.properties.getCompression().getAllMimeTypes()).contains(new Compression().getMimeTypes());
+		assertThat(this.properties.getCompression().getAllMimeTypes()).contains("application/zip");
+	}
+
 	private void bind(String name, String value) {
 		bind(Collections.singletonMap(name, value));
 	}