Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, * software distributed under the License is distributed on an * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * KIND, either express or implied. See the License for the * specific language governing permissions and limitations * under the License. */ package org.apache.felix.ipojo.manipulator.metadata.annotation; import org.apache.felix.ipojo.manipulator.Reporter; import org.apache.felix.ipojo.manipulator.metadata.annotation.registry.BindingRegistry; import org.apache.felix.ipojo.metadata.Attribute; import org.apache.felix.ipojo.metadata.Element; import org.objectweb.asm.*; import org.objectweb.asm.tree.ClassNode; import org.objectweb.asm.tree.FieldNode; import org.objectweb.asm.tree.MethodNode; /** * @author <a href="mailto:dev@felix.apache.org">Felix Project Team</a> */ public class ClassMetadataCollector extends ClassVisitor { /** * Binding's registry. */ private BindingRegistry registry; /** * Output information. */ private Reporter reporter; /** * Workbench where produced Elements will be merged and hierarchically organized. */ private ComponentWorkbench workbench; /** * Class currently being analyzed. */ private ClassNode node; private Element componentMetadata; private Element instanceMetadata; public ClassMetadataCollector(BindingRegistry registry, Reporter reporter) { super(Opcodes.ASM5); this.registry = registry; this.reporter = reporter; node = new ClassNode(); } /** * Build metadata. May be {@literal null} if no "component type" was found. * * @return Build metadata. May be {@literal null} if no "component type" was found. */ public Element getComponentMetadata() { return componentMetadata; } /** * Build instance metadata. May be {@literal null} if no "component type" was found. * * @return Build metadata. May be {@literal null} if no "component type" was found. */ public Element getInstanceMetadata() { return instanceMetadata; } @Override public void visit(int version, int access, String name, String signature, String superName, String[] interfaces) { node.visit(version, access, name, signature, superName, interfaces); workbench = new ComponentWorkbench(registry, node); } /** * Visit class annotations. * This method detects @component and @provides annotations. * * @param desc : annotation descriptor. * @param visible : is the annotation visible at runtime. * @return the annotation visitor. * @see org.objectweb.asm.ClassVisitor#visitAnnotation(java.lang.String, boolean) */ public AnnotationVisitor visitAnnotation(String desc, boolean visible) { //TODO we should find a better way to do this. // Cannot retrieve the class object as @Configuration is in iPOJO runtime. if (Type.getType(desc).getClassName().equals("org.apache.felix.ipojo.configuration.Configuration")) { workbench.ignore(true); return null; } // Return the visitor to be executed (may be null) return registry.selection(workbench).type(this, node).annotatedWith(desc).get(); } /** * Visit a field. * Call the field collector visitor. * * @param access : field access. * @param name : field name * @param desc : field descriptor * @param signature : field signature * @param value : field value (static field only) * @return the field visitor. * @see org.objectweb.asm.ClassVisitor#visitField(int, java.lang.String, java.lang.String, java.lang.String, * java.lang.Object) */ public FieldVisitor visitField(int access, String name, String desc, String signature, Object value) { return new FieldMetadataCollector(workbench, new FieldNode(access, name, desc, signature, value)); } /** * Visit a method. * Call the method collector visitor. * * @param access : method access * @param name : method name * @param desc : method descriptor * @param signature : method signature * @param exceptions : method exceptions * @return the Method Visitor. * @see org.objectweb.asm.ClassVisitor#visitMethod(int, java.lang.String, java.lang.String, java.lang.String, java.lang.String[]) */ public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) { return new MethodMetadataCollector(workbench, new MethodNode(access, name, desc, signature, exceptions), reporter); } /** * End of the visit : compute final elements. * * @see org.objectweb.asm.ClassVisitor#visitEnd() */ @Override public void visitEnd() { // Only process real class (no annotations, no interfaces) if (!(is(Opcodes.ACC_ANNOTATION) || is(Opcodes.ACC_INTERFACE) || is(Opcodes.ACC_ABSTRACT))) { if (workbench.getRoot() == null) { // No 'top-level' element has been contributed if (workbench.ignore()) { // Ignore this class. return; } if (!workbench.getElements().isEmpty()) { // There are other annotation's contribution on this type (additional handler declaration/configuration) // That means that there is a missing 'component type' annotation reporter.warn( "Class %s has not been marked as a component type (no @Component, @Handler, " + "...). It will be ignored by the iPOJO manipulator.", workbench.getType().getClassName()); return; } // else: no root and no elements return; } componentMetadata = workbench.build(); instanceMetadata = workbench.getInstance(); // If we have an instance declared and the component metadata has a name, we update the component's attribute // of the instance (https://issues.apache.org/jira/browse/FELIX-4052). if (componentMetadata != null && componentMetadata.containsAttribute("name") && instanceMetadata != null) { // Update the component attribute instanceMetadata.addAttribute(new Attribute("component", componentMetadata.getAttribute("name"))); } } } private boolean is(int flags) { return (node.access & flags) == flags; } }