org.apache.juneau.rest.arg.DefaultArg Maven / Gradle / Ivy

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// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
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package org.apache.juneau.rest.arg;

import static org.apache.juneau.common.internal.StringUtils.*;

import java.lang.annotation.*;

import org.apache.juneau.cp.*;
import org.apache.juneau.reflect.*;
import org.apache.juneau.rest.*;
import org.apache.juneau.rest.annotation.*;

/**
 * Resolves method parameters on {@link RestOp}-annotated Java methods by retrieving them by type from the REST object bean store.
 *
 * 
 * The parameter value is resolved using:
 * 

 * 	opSession
 * 		.{@link RestOpSession#getBeanStore() getBeanStore}()
 * 		.{@link BeanStore#getBean(Class) getBean}(type);
 * 
 *
 * 
 * This is the default parameter resolver if no other applicable parameter resolvers could be found.
 *
 * 
See Also:

 * 	Java Method Parameters
 * 
 */
public class DefaultArg implements RestOpArg {

	private final Class type;
	private final String name;
	private final ParamInfo paramInfo;

	/**
	 * Static creator.
	 *
	 * @param paramInfo The Java method parameter being resolved.
	 * @return A new {@link DefaultArg}, never null.
	 */
	public static DefaultArg create(ParamInfo paramInfo) {
		return new DefaultArg(paramInfo);
	}

	/**
	 * Constructor.
	 *
	 * @param paramInfo The Java method parameter being resolved.
	 */
	protected DefaultArg(ParamInfo paramInfo) {
		this.type = paramInfo.getParameterType().inner();
		this.paramInfo = paramInfo;
		this.name = findBeanName(paramInfo);
	}

	//-----------------------------------------------------------------------------------------------------------------
	// Helper methods
	//-----------------------------------------------------------------------------------------------------------------
	private String findBeanName(ParamInfo pi) {
		Annotation n = pi.getAnnotation(Annotation.class, x -> x.annotationType().getSimpleName().equals("Named"));
		if (n != null)
			return AnnotationInfo.of((ClassInfo)null, n).getValue(String.class, "value", NOT_EMPTY).orElse(null);
		return null;
	}

	@Override /* RestOpArg */
	public Object resolve(RestOpSession opSession) throws Exception {
		return opSession.getBeanStore().getBean(type, name).orElseThrow(()->new ArgException(paramInfo, "Could not resolve bean type {0}", type.getName()));
	}
}