Add JCommander parameter resolver

pom.xml

@@ -39,6 +39,12 @@
 			<artifactId>spring-shell</artifactId>
 			<version>1.2.0.BUILD-SNAPSHOT</version>
 		</dependency>
+		<dependency>
+			<groupId>com.beust</groupId>
+			<artifactId>jcommander</artifactId>
+			<version>1.48</version>
+			<optional>true</optional>
+		</dependency>
 	</dependencies>
 
 	<build>

src/main/java/org/springframework/shell2/jcommander/JCommanderParameterResolver.java

@@ -0,0 +1,63 @@
+package org.springframework.shell2.jcommander;
+
+import java.lang.annotation.Annotation;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.List;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import com.beust.jcommander.DynamicParameter;
+import com.beust.jcommander.JCommander;
+import com.beust.jcommander.Parameter;
+import com.beust.jcommander.ParametersDelegate;
+
+import org.springframework.beans.BeanUtils;
+import org.springframework.core.MethodParameter;
+import org.springframework.shell2.ParameterResolver;
+import org.springframework.util.ReflectionUtils;
+
+/**
+ * Created by ericbottard on 15/12/15.
+ */
+public class JCommanderParameterResolver implements ParameterResolver {
+
+	private static final Collection<Class<? extends Annotation>> JCOMMANDER_ANNOTATIONS =
+			Arrays.asList(Parameter.class, DynamicParameter.class, ParametersDelegate.class);
+
+	@Override
+	public boolean supports(MethodParameter parameter) {
+		AtomicBoolean isSupported = new AtomicBoolean(false);
+
+		Class<?> parameterType = parameter.getParameterType();
+		ReflectionUtils.doWithFields(parameterType, field -> {
+			ReflectionUtils.makeAccessible(field);
+			boolean hasAnnotation = Arrays.asList(field.getAnnotations())
+					.stream()
+					.map(Annotation::annotationType)
+					.anyMatch(JCOMMANDER_ANNOTATIONS::contains);
+			isSupported.compareAndSet(false, hasAnnotation);
+
+		});
+
+		ReflectionUtils.doWithMethods(parameterType, method -> {
+			ReflectionUtils.makeAccessible(method);
+			boolean hasAnnotation = Arrays.asList(method.getAnnotations())
+					.stream()
+					.map(Annotation::annotationType)
+					.anyMatch(Parameter.class::equals);
+			isSupported.compareAndSet(false, hasAnnotation);
+		});
+		return isSupported.get();
+	}
+
+	@Override
+	public Object resolve(MethodParameter methodParameter, List<String> words) {
+		Object pojo = BeanUtils.instantiateClass(methodParameter.getParameterType());
+		JCommander jCommander = new JCommander();
+		jCommander.addObject(pojo);
+		jCommander.setAcceptUnknownOptions(true);
+		jCommander.parse(words.toArray(new String[words.size()]));
+		return pojo;
+	}
+
+}

src/test/java/org/springframework/shell2/jcommander/FieldCollins.java

@@ -0,0 +1,45 @@
+package org.springframework.shell2.jcommander;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import com.beust.jcommander.Parameter;
+
+/**
+ * Created by ericbottard on 15/12/15.
+ */
+public class FieldCollins {
+
+	@Parameter(names = "--name")
+	private String name;
+
+	@Parameter(names = "-level")
+	private int level;
+
+	@Parameter(description = "rest")
+	private List<String> rest = new ArrayList<>();
+
+	public List<String> getRest() {
+		return rest;
+	}
+
+	public void setRest(List<String> rest) {
+		this.rest = rest;
+	}
+
+	public String getName() {
+		return name;
+	}
+
+	public void setName(String name) {
+		this.name = name;
+	}
+
+	public int getLevel() {
+		return level;
+	}
+
+	public void setLevel(int level) {
+		this.level = level;
+	}
+}

src/test/java/org/springframework/shell2/jcommander/JCommanderParameterResolverTest.java

@@ -0,0 +1,45 @@
+package org.springframework.shell2.jcommander;
+
+import static java.util.Arrays.asList;
+import static org.hamcrest.Matchers.contains;
+import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.assertThat;
+
+import java.lang.reflect.Method;
+
+import org.junit.Test;
+
+import org.springframework.core.MethodParameter;
+import org.springframework.util.ReflectionUtils;
+
+/**
+ * Created by ericbottard on 15/12/15.
+ */
+public class JCommanderParameterResolverTest {
+
+	public static final Method COMMAND_METHOD = ReflectionUtils.findMethod(MyLordCommands.class, "genesis", FieldCollins.class);
+
+	private JCommanderParameterResolver resolver = new JCommanderParameterResolver();
+
+	@Test
+	public void testSupportsJCommanderPojos() throws Exception {
+
+		assertThat(resolver.supports(new MethodParameter(COMMAND_METHOD, 0)), is(true));
+	}
+
+	@Test
+	public void testDoesNotSupportsNonJCommanderPojos() throws Exception {
+		Method method = ReflectionUtils.findMethod(MyLordCommands.class, "apocalypse", String.class);
+
+		assertThat(resolver.supports(new MethodParameter(method, 0)), is(false));
+	}
+
+	@Test
+	public void testPojoValuesAreCorrectlySet() {
+		MethodParameter methodParameter = new MethodParameter(COMMAND_METHOD, 0);
+		FieldCollins resolved = (FieldCollins) resolver.resolve(methodParameter, asList("--name foo -level 2 something-else yet-something-else".split(" ")));
+		assertThat(resolved.getName(), is("foo"));
+		assertThat(resolved.getLevel(), is(2));
+		assertThat(resolved.getRest(), contains("something-else", "yet-something-else"));
+	}
+}

src/test/java/org/springframework/shell2/jcommander/MyLordCommands.java

@@ -0,0 +1,16 @@
+package org.springframework.shell2.jcommander;
+
+/**
+ * Created by ericbottard on 15/12/15.
+ */
+public class MyLordCommands {
+
+	public void genesis(FieldCollins fieldCollins) {
+
+	}
+
+	public void apocalypse(String param) {
+
+	}
+
+}