Allow to disable structured logging for Log4j2

Closes GH-45407

Signed-off-by: Yanming Zhou <[email protected]>

Author: quaff

spring-boot-project/spring-boot/src/main/resources/org/springframework/boot/logging/log4j2/log4j2-file.xml

@@ -10,6 +10,9 @@
 	<Appenders>
 		<Console name="Console" target="SYSTEM_OUT" follow="true">
 			<Select>
+				<SystemPropertyArbiter propertyName="CONSOLE_LOG_STRUCTURED_FORMAT" propertyValue="">
+					<PatternLayout pattern="${sys:CONSOLE_LOG_PATTERN}" charset="${sys:CONSOLE_LOG_CHARSET}"/>
+				</SystemPropertyArbiter>
 				<SystemPropertyArbiter propertyName="CONSOLE_LOG_STRUCTURED_FORMAT">
 					<StructuredLogLayout format="${sys:CONSOLE_LOG_STRUCTURED_FORMAT}" charset="${sys:CONSOLE_LOG_CHARSET}"/>
 				</SystemPropertyArbiter>
@@ -23,6 +26,9 @@
 		</Console>
 		<RollingFile name="File" fileName="${sys:LOG_FILE}" filePattern="${sys:LOG_PATH}/$${date:yyyy-MM}/app-%d{yyyy-MM-dd-HH}-%i.log.gz">
 			<Select>
+				<SystemPropertyArbiter propertyName="FILE_LOG_STRUCTURED_FORMAT" propertyValue="">
+					<PatternLayout pattern="${sys:FILE_LOG_PATTERN}" charset="${sys:FILE_LOG_CHARSET}"/>
+				</SystemPropertyArbiter>
 				<SystemPropertyArbiter propertyName="FILE_LOG_STRUCTURED_FORMAT">
 					<StructuredLogLayout format="${sys:FILE_LOG_STRUCTURED_FORMAT}" charset="${sys:FILE_LOG_CHARSET}"/>
 				</SystemPropertyArbiter>

spring-boot-project/spring-boot/src/main/resources/org/springframework/boot/logging/log4j2/log4j2.xml

@@ -10,6 +10,9 @@
 	<Appenders>
 		<Console name="Console" target="SYSTEM_OUT" follow="true">
 			<Select>
+				<SystemPropertyArbiter propertyName="CONSOLE_LOG_STRUCTURED_FORMAT" propertyValue="">
+					<PatternLayout pattern="${sys:CONSOLE_LOG_PATTERN}" charset="${sys:CONSOLE_LOG_CHARSET}"/>
+				</SystemPropertyArbiter>
 				<SystemPropertyArbiter propertyName="CONSOLE_LOG_STRUCTURED_FORMAT">
 					<StructuredLogLayout format="${sys:CONSOLE_LOG_STRUCTURED_FORMAT}" charset="${sys:CONSOLE_LOG_CHARSET}"/>
 				</SystemPropertyArbiter>

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/logging/log4j2/Log4j2FileXmlTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -32,6 +32,7 @@
  *
  * @author Andy Wilkinson
  * @author Scott Frederick
+ * @author Yanming Zhou
  */
 class Log4j2FileXmlTests extends Log4j2XmlTests {
 
@@ -80,6 +81,12 @@ void whenLogDateformatPatternIsSetThenFileAppenderUsesIt() {
 				() -> assertThat(fileAppenderPattern()).contains("dd-MM-yyyy"));
 	}
 
+	@Test
+	void whenFileLogStructuredFormatIsEmptyThenFallbackToPatternLayout() {
+		withSystemProperty(LoggingSystemProperty.FILE_STRUCTURED_FORMAT.getEnvironmentVariableName(), "",
+				() -> assertThat(fileAppenderPattern()).contains("yyyy-MM-dd'T'HH:mm:ss.SSSXXX"));
+	}
+
 	@Override
 	protected String getConfigFileName() {
 		return "log4j2-file.xml";

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/logging/log4j2/Log4j2XmlTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -36,6 +36,7 @@
  *
  * @author Andy Wilkinson
  * @author Scott Frederick
+ * @author Yanming Zhou
  */
 class Log4j2XmlTests {
 
@@ -79,6 +80,12 @@ void whenLogDateformatPatternIsSetThenConsoleUsesIt() {
 				() -> assertThat(consolePattern()).contains("dd-MM-yyyy"));
 	}
 
+	@Test
+	void whenConsoleStructuredFormatIsEmptyThenFallbackToPatternLayout() {
+		withSystemProperty(LoggingSystemProperty.CONSOLE_STRUCTURED_FORMAT.getEnvironmentVariableName(), "",
+				() -> assertThat(consolePattern()).contains("yyyy-MM-dd'T'HH:mm:ss.SSSXXX"));
+	}
+
 	protected void withSystemProperty(String name, String value, Runnable action) {
 		String previous = System.setProperty(name, value);
 		action.run();