Introduce new command builder DSL

.editorconfig

@@ -0,0 +1,5 @@
+root = true
+
+[*.{java,xml,gradle}]
+indent_style = tab
+indent_size = 4

spring-shell-core/src/main/java/org/springframework/shell/core/command/Command.java

@@ -13,11 +13,20 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
 package org.springframework.shell.core.command;
 
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
+import java.util.function.Consumer;
+import java.util.function.Function;
+
+import org.jspecify.annotations.Nullable;
+
+import org.springframework.shell.core.commands.AbstractCommand;
+import org.springframework.shell.core.commands.adapter.ConsumerCommandAdapter;
+import org.springframework.shell.core.commands.adapter.FunctionCommandAdapter;
+import org.springframework.util.Assert;
 
 /**
  * @author Eric Bottard
@@ -74,4 +83,88 @@ default List<String> getAliases() {
 	 */
 	ExitStatus execute(CommandContext commandContext) throws Exception;
 
+	/**
+	 * Creates and returns a new instance of a {@code Builder} for defining and
+	 * constructing commands.
+	 * <p>
+	 * The builder allows customization of command properties such as name, description,
+	 * group, help text, aliases, and execution logic.
+	 * @return a new {@code Builder} instance for configuring and creating commands
+	 */
+	static Builder builder() {
+		return new Builder();
+	}
+
+	/**
+	 * Builder for creating command.
+	 */
+	final class Builder {
+
+		private @Nullable String name;
+
+		private @Nullable String description;
+
+		private String group = "";
+
+		private String help = "";
+
+		private @Nullable List<String> aliases;
+
+		public Builder name(String name) {
+			this.name = name;
+			return this;
+		}
+
+		public Builder description(String description) {
+			this.description = description;
+			return this;
+		}
+
+		public Builder help(String help) {
+			this.help = help;
+			return this;
+		}
+
+		public Builder group(String group) {
+			this.group = group;
+			return this;
+		}
+
+		public Builder aliases(String... aliases) {
+			this.aliases = Arrays.asList(aliases);
+			return this;
+		}
+
+		public Command execute(Consumer<CommandContext> commandExecutor) {
+			Assert.hasText(name, "'name' must be specified");
+			Assert.hasText(description, "description");
+
+			ConsumerCommandAdapter command = new ConsumerCommandAdapter(name, description, group, help,
+					commandExecutor);
+
+			initAliases(command);
+
+			return command;
+		}
+
+		public Command execute(Function<CommandContext, String> commandExecutor) {
+			Assert.hasText(name, "'name' must be specified");
+			Assert.hasText(description, "'description' must be specified");
+
+			FunctionCommandAdapter command = new FunctionCommandAdapter(name, description, group, help,
+					commandExecutor);
+
+			initAliases(command);
+
+			return command;
+		}
+
+		private void initAliases(AbstractCommand command) {
+			if (aliases != null) {
+				command.setAliases(aliases);
+			}
+		}
+
+	}
+
 }

spring-shell-core/src/main/java/org/springframework/shell/core/command/annotation/support/EnableCommandRegistrar.java

@@ -17,7 +17,6 @@
 
 import java.io.IOException;
 import java.lang.reflect.Method;
-import java.util.Arrays;
 import java.util.Set;
 
 import org.jline.reader.LineReader;
@@ -45,6 +44,7 @@
  *
  * @author Janne Valkealahti
  * @author Mahmoud Ben Hassine
+ * @author Piotr Olaszewski
  */
 public final class EnableCommandRegistrar implements ImportBeanDefinitionRegistrar {
 
@@ -62,7 +62,6 @@ public void registerBeanDefinitions(AnnotationMetadata metadata, BeanDefinitionR
 		// register user defined commands
 		Class<?>[] candidateClasses = shellAnnotation.value();
 		for (Class<?> candidateClass : candidateClasses) {
-			registerCommands(candidateClass, registry);
 			registerAnnotatedMethods(candidateClass, registry);
 		}
 
@@ -108,16 +107,6 @@ public void registerBeanDefinitions(AnnotationMetadata metadata, BeanDefinitionR
 		}
 	}
 
-	private void registerCommands(Class<?> candidateClass, BeanDefinitionRegistry registry) {
-		Arrays.stream(candidateClass.getDeclaredMethods())
-			.filter(method -> method.getReturnType().equals(org.springframework.shell.core.command.Command.class))
-			.forEach(method -> {
-				RootBeanDefinition beanDefinition = new RootBeanDefinition(
-						org.springframework.shell.core.command.Command.class);
-				registry.registerBeanDefinition(method.getName(), beanDefinition);
-			});
-	}
-
 	private void registerAnnotatedMethods(Class<?> candidateClass, BeanDefinitionRegistry registry) {
 		ReflectionUtils.MethodFilter filter = method -> AnnotatedElementUtils.hasAnnotation(method, Command.class);
 		Set<Method> methods = MethodIntrospector.selectMethods(candidateClass, filter);

spring-shell-core/src/main/java/org/springframework/shell/core/commands/AbstractCommand.java

@@ -97,10 +97,10 @@ public ExitStatus execute(CommandContext commandContext) throws Exception {
 		return doExecute(commandContext);
 	}
 
+	public abstract ExitStatus doExecute(CommandContext commandContext) throws Exception;
+
 	private static boolean isHelp(CommandOption option) {
 		return option.longName().equalsIgnoreCase("help") || option.shortName() == 'h';
 	}
 
-	public abstract ExitStatus doExecute(CommandContext commandContext) throws Exception;
-
 }

spring-shell-core/src/main/java/org/springframework/shell/core/commands/adapter/package-info.java

@@ -0,0 +1,4 @@
+@NullMarked
+package org.springframework.shell.core.commands.adapter;
+
+import org.jspecify.annotations.NullMarked;

spring-shell-samples/spring-shell-sample-hello-world/src/main/java/org/springframework/shell/samples/helloworld/SpringShellApplication.java

@@ -3,13 +3,19 @@
 import java.util.List;
 
 import org.jline.terminal.Terminal;
+import org.jline.utils.AttributedStringBuilder;
 
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.shell.core.ShellRunner;
 import org.springframework.shell.core.command.CommandContext;
-import org.springframework.shell.core.command.annotation.*;
+import org.springframework.shell.core.command.annotation.Argument;
+import org.springframework.shell.core.command.annotation.Arguments;
+import org.springframework.shell.core.command.annotation.Command;
+import org.springframework.shell.core.command.annotation.EnableCommand;
+import org.springframework.shell.core.command.annotation.Option;
+import static org.jline.utils.AttributedStyle.*;
 
 @EnableCommand(SpringShellApplication.class)
 public class SpringShellApplication {
@@ -43,6 +49,35 @@ public void sayYo(CommandContext commandContext) {
 		terminal.writer().println("Yo there! what's up?");
 	}
 
+	@Bean
+	public org.springframework.shell.core.command.Command sayGoodMorning() {
+		return org.springframework.shell.core.command.Command.builder()
+			.name("good-morning")
+			.description("Say good morning")
+			.group("greetings")
+			.help("A command that greets the user with 'Good morning!'")
+			.execute(commandContext -> {
+				String ansiString = new AttributedStringBuilder().append("Good morning ")
+					.append("Sir", BOLD.foreground(GREEN))
+					.append("!")
+					.toAnsi();
+
+				Terminal terminal = commandContext.terminal();
+				terminal.writer().println(ansiString);
+				terminal.flush();
+			});
+	}
+
+	@Bean
+	public org.springframework.shell.core.command.Command sayGoodDay() {
+		return org.springframework.shell.core.command.Command.builder()
+			.name("good-day")
+			.description("Say good day")
+			.group("greetings")
+			.help("A command that greets the user with 'Good day!'")
+			.execute(commandContext -> "Good day!");
+	}
+
 	@Bean
 	public HelloCommand sayHello() {
 		return new HelloCommand();