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 +13,13 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
 package org.springframework.shell.core.command;
 
 import java.util.Collections;
 import java.util.List;
+import java.util.function.Consumer;
+
+import org.springframework.shell.core.commands.AbstractCommand;
 
 /**
  * @author Eric Bottard
@@ -74,4 +76,70 @@ 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 DefaultCommandBuilder();
+	}
+
+	/**
+	 * Builder for creating command.
+	 */
+	interface Builder {
+
+		/**
+		 * Set the name of the command.
+		 * @return this builder
+		 */
+		Builder name(String name);
+
+		/**
+		 * Set the description of the command.
+		 * @return this builder
+		 */
+		Builder description(String description);
+
+		/**
+		 * Set the help of the command.
+		 * @return this builder
+		 */
+		Builder help(String help);
+
+		/**
+		 * Set the group of the command.
+		 * @return this builder
+		 */
+		Builder group(String group);
+
+		/**
+		 * Set the aliases of the command.
+		 * @return this builder
+		 */
+		Builder aliases(String... aliases);
+
+		/**
+		 * Set the aliases of the command.
+		 * @return this builder
+		 */
+		Builder aliases(List<String> aliases);
+
+		/**
+		 * Set command execution logic.
+		 * @return this builder
+		 */
+		Builder execute(Consumer<CommandContext> commandExecutor);
+
+		/**
+		 * Build the {@link AbstractCommand}.
+		 */
+		AbstractCommand build();
+
+	}
+
 }

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

@@ -0,0 +1,94 @@
+package org.springframework.shell.core.command;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.function.Consumer;
+
+import org.jspecify.annotations.Nullable;
+
+import org.springframework.shell.core.commands.AbstractCommand;
+import org.springframework.shell.core.commands.adapter.ConsumerCommandAdapter;
+import org.springframework.util.Assert;
+import static org.springframework.shell.core.command.Command.*;
+
+/**
+ * Default implementation of {@link Builder}.
+ *
+ * @author Piotr Olaszewski
+ */
+class DefaultCommandBuilder implements Builder {
+
+	private @Nullable String name;
+
+	private @Nullable String description;
+
+	private String group = "";
+
+	private String help = "";
+
+	private @Nullable List<String> aliases;
+
+	private @Nullable Consumer<CommandContext> commandContextConsumer;
+
+	@Override
+	public Builder name(String name) {
+		this.name = name;
+		return this;
+	}
+
+	@Override
+	public Builder description(String description) {
+		this.description = description;
+		return this;
+	}
+
+	@Override
+	public Builder help(String help) {
+		this.help = help;
+		return this;
+	}
+
+	@Override
+	public Builder group(String group) {
+		this.group = group;
+		return this;
+	}
+
+	@Override
+	public Builder aliases(String... aliases) {
+		this.aliases = Arrays.asList(aliases);
+		return this;
+	}
+
+	@Override
+	public Builder aliases(List<String> aliases) {
+		this.aliases = aliases;
+		return this;
+	}
+
+	@Override
+	public Builder execute(Consumer<CommandContext> commandExecutor) {
+		this.commandContextConsumer = commandExecutor;
+		return this;
+	}
+
+	@Override
+	public AbstractCommand build() {
+		ConsumerCommandAdapter abstractCommand = initCommand();
+
+		if (aliases != null) {
+			abstractCommand.setAliases(aliases);
+		}
+
+		return abstractCommand;
+	}
+
+	private ConsumerCommandAdapter initCommand() {
+		Assert.hasText(name, "'name' must be specified");
+		Assert.hasText(description, "description");
+		Assert.notNull(commandContextConsumer, "'commandExecutor' must not be null");
+
+		return new ConsumerCommandAdapter(name, description, group, help, commandContextConsumer);
+	}
+
+}

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 +3,20 @@
 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 org.springframework.shell.core.commands.AbstractCommand;
+import static org.jline.utils.AttributedStyle.*;
 
 @EnableCommand(SpringShellApplication.class)
 public class SpringShellApplication {
@@ -43,6 +50,26 @@ public void sayYo(CommandContext commandContext) {
 		terminal.writer().println("Yo there! what's up?");
 	}
 
+	@Bean
+	public AbstractCommand 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();
+			})
+			.build();
+	}
+
 	@Bean
 	public HelloCommand sayHello() {
 		return new HelloCommand();