Support Ordered and @Order for exit code generation

spring-boot-project/spring-boot-docs/src/docs/asciidoc/features/spring-application.adoc

@@ -352,7 +352,8 @@ include::code:MyApplication[]
 Also, the `ExitCodeGenerator` interface may be implemented by exceptions.
 When such an exception is encountered, Spring Boot returns the exit code provided by the implemented `getExitCode()` method.
 
-
+If several `ExitCodeGenerator` are registered in a `ExitCodeGenerators`, they can be called in a specific order by using `org.springframework.core.annotation.Order` annotation or by implementing `org.springframework.core.Ordered`,
+and `ExitCodeGenerators#getExitCode()` will return the first non-zero value.
 
 [[features.spring-application.admin]]
 === Admin Features

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/ExitCodeGenerators.java

@@ -21,14 +21,22 @@
 import java.util.Iterator;
 import java.util.List;
 
+import org.springframework.core.Ordered;
+import org.springframework.core.annotation.AnnotationAwareOrderComparator;
+import org.springframework.core.annotation.Order;
 import org.springframework.util.Assert;
 
 /**
  * Maintains a collection of {@link ExitCodeGenerator} instances and allows the final exit
  * code to be calculated.
  *
+ * <p>If several {@code ExitCodeGenerator} are registered in {@code ExitCodeGenerators},
+ * they can be called in a specific order by using {@link Order @Order} or by implementing {@link Ordered},
+ * and {@link #getExitCode()} will return the first non-zero value.
+ *
  * @author Dave Syer
  * @author Phillip Webb
+ * @author GenKui Du
  * @see #getExitCode()
  * @see ExitCodeGenerator
  */
@@ -84,15 +92,17 @@ public Iterator<ExitCodeGenerator> iterator() {
 	 */
 	int getExitCode() {
 		int exitCode = 0;
+		AnnotationAwareOrderComparator.sort(this.generators);
 		for (ExitCodeGenerator generator : this.generators) {
 			try {
 				int value = generator.getExitCode();
-				if (value > 0 && value > exitCode || value < 0 && value < exitCode) {
+				if (value != 0) {
 					exitCode = value;
+					break;
 				}
 			}
 			catch (Exception ex) {
-				exitCode = (exitCode != 0) ? exitCode : 1;
+				exitCode = 1;
 				ex.printStackTrace();
 			}
 		}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/ExitCodeGeneratorsTests.java

@@ -20,11 +20,13 @@
 import java.util.List;
 
 import org.junit.jupiter.api.Test;
+import org.springframework.core.Ordered;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 import static org.mockito.BDDMockito.given;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.withSettings;
 
 /**
  * Tests for {@link ExitCodeGenerators}.
@@ -89,12 +91,29 @@ void getExitCodeWhenUsingExitCodeExceptionMapperShouldCallMapper() {
 		assertThat(generators.getExitCode()).isEqualTo(2);
 	}
 
+	@Test
+	void getExitCodeWithOrderedGenerator() {
+		ExitCodeGenerators generators = new ExitCodeGenerators();
+		generators.add(mockGenerator(0, 1));
+		generators.add(mockGenerator(1, 3));
+		generators.add(mockGenerator(2, 2));
+		generators.add(mockGenerator(3, 4));
+		assertThat(generators.getExitCode()).isEqualTo(2);
+	}
+
 	private ExitCodeGenerator mockGenerator(int exitCode) {
 		ExitCodeGenerator generator = mock(ExitCodeGenerator.class);
 		given(generator.getExitCode()).willReturn(exitCode);
 		return generator;
 	}
 
+	private ExitCodeGenerator mockGenerator(int exitCode, int orderValue) {
+		ExitCodeGenerator generator = mock(ExitCodeGenerator.class, withSettings().extraInterfaces(Ordered.class));
+		given(generator.getExitCode()).willReturn(exitCode);
+		given(((Ordered) generator).getOrder()).willReturn(orderValue);
+		return generator;
+	}
+
 	private ExitCodeExceptionMapper mockMapper(Class<?> exceptionType, int exitCode) {
 		return (exception) -> {
 			if (exceptionType.isInstance(exception)) {