injectexternallinkannotationworker.java

tapestry4.0应用,特别适用于初学者

package com.cucu.tapestry.annotation;

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

import org.apache.hivemind.ApplicationRuntimeException;
import org.apache.hivemind.Location;
import org.apache.hivemind.service.BodyBuilder;
import org.apache.hivemind.service.MethodSignature;
import org.apache.tapestry.Tapestry;
import org.apache.tapestry.annotations.AnnotationUtils;
import org.apache.tapestry.annotations.MethodAnnotationEnhancementWorker;
import org.apache.tapestry.engine.ILink;
import org.apache.tapestry.enhance.EnhancementOperation;
import org.apache.tapestry.spec.IComponentSpecification;

/**
 * @author Chris
 * @version $Id$
 */
public class InjectExternalLinkAnnotationWorker implements MethodAnnotationEnhancementWorker {
    public void performEnhancement(EnhancementOperation op, IComponentSpecification spec, Method method, Location location) {
        if (!method.getReturnType().equals(ILink.class))
            throw new ApplicationRuntimeException("injectExternalLink annotation must return ILink");
        InjectExternalLink injectExternalLink = method.getAnnotation(InjectExternalLink.class);
        String pageName = injectExternalLink.value();
        BodyBuilder builder = new BodyBuilder();
        builder.begin();
        Class[] parameterTypes = method.getParameterTypes();
        int paramCount = Tapestry.size(parameterTypes);
        if (paramCount > 0) {
            if (parameterTypes[0].isArray()) {
                builder.addln("return getPage().getRequestCycle().getInfrastructure().getServiceMap().getService(org.apache.tapestry.Tapestry.EXTERNAL_SERVICE).getLink(false, new org.apache.tapestry.engine.ExternalServiceParameter(\"{0}\",$1));", pageName);
            } else {
                builder.addln("java.lang.Object[] params = new java.lang.Object[{0}];", paramCount);
                for (int i = 0; i < paramCount; i++) {
                    builder.add("params[{0}] = ", i);
                    if (parameterTypes[i].isPrimitive())
                        builder.add("($w) ");   // Parameter $0 is this, so $1 is the first real parameter.
                    builder.addln("${0};", i + 1);
                }
                builder.addln("return getPage().getRequestCycle().getInfrastructure().getServiceMap().getService(org.apache.tapestry.Tapestry.EXTERNAL_SERVICE).getLink(false, new org.apache.tapestry.engine.ExternalServiceParameter(\"{0}\",params));", pageName);
            }
        }
        builder.end();
        op.addMethod(Modifier.PUBLIC, new MethodSignature(method), builder.toString(), location);
        if (isGetter(method)) op.claimReadonlyProperty(AnnotationUtils.getPropertyName(method));
    }

    boolean isGetter(Method method) {          // We already know the return type is String
        return method.getName().startsWith("get") && method.getParameterTypes().length == 0;
    }
}