Java tutorial
// ASM: a very small and fast Java bytecode manipulation framework // Copyright (c) 2000-2011 INRIA, France Telecom // All rights reserved. // // Redistribution and use in source and binary forms, with or without // modification, are permitted provided that the following conditions // are met: // 1. Redistributions of source code must retain the above copyright // notice, this list of conditions and the following disclaimer. // 2. Redistributions in binary form must reproduce the above copyright // notice, this list of conditions and the following disclaimer in the // documentation and/or other materials provided with the distribution. // 3. Neither the name of the copyright holders nor the names of its // contributors may be used to endorse or promote products derived from // this software without specific prior written permission. // // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE // ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE // LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR // CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN // CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF // THE POSSIBILITY OF SUCH DAMAGE. package org.springframework.asm; /** * A visitor to visit a Java annotation. The methods of this class must be called in the following * order: ( {@code visit} | {@code visitEnum} | {@code visitAnnotation} | {@code visitArray} )* * {@code visitEnd}. * * @author Eric Bruneton * @author Eugene Kuleshov */ public abstract class AnnotationVisitor { /** * The ASM API version implemented by this visitor. The value of this field must be one of {@link * Opcodes#ASM4}, {@link Opcodes#ASM5}, {@link Opcodes#ASM6} or {@link Opcodes#ASM7}. */ protected final int api; /** * The annotation visitor to which this visitor must delegate method calls. May be {@literal * null}. */ protected AnnotationVisitor av; /** * Constructs a new {@link AnnotationVisitor}. * * @param api the ASM API version implemented by this visitor. Must be one of {@link * Opcodes#ASM4}, {@link Opcodes#ASM5}, {@link Opcodes#ASM6} or {@link Opcodes#ASM7}. */ public AnnotationVisitor(final int api) { this(api, null); } /** * Constructs a new {@link AnnotationVisitor}. * * @param api the ASM API version implemented by this visitor. Must be one of {@link * Opcodes#ASM4}, {@link Opcodes#ASM5}, {@link Opcodes#ASM6} or {@link Opcodes#ASM7}. * @param annotationVisitor the annotation visitor to which this visitor must delegate method * calls. May be {@literal null}. */ public AnnotationVisitor(final int api, final AnnotationVisitor annotationVisitor) { if (api != Opcodes.ASM7 && api != Opcodes.ASM6 && api != Opcodes.ASM5 && api != Opcodes.ASM4) { throw new IllegalArgumentException("Unsupported api " + api); } this.api = api; this.av = annotationVisitor; } /** * Visits a primitive value of the annotation. * * @param name the value name. * @param value the actual value, whose type must be {@link Byte}, {@link Boolean}, {@link * Character}, {@link Short}, {@link Integer} , {@link Long}, {@link Float}, {@link Double}, * {@link String} or {@link Type} of {@link Type#OBJECT} or {@link Type#ARRAY} sort. This * value can also be an array of byte, boolean, short, char, int, long, float or double values * (this is equivalent to using {@link #visitArray} and visiting each array element in turn, * but is more convenient). */ public void visit(final String name, final Object value) { if (av != null) { av.visit(name, value); } } /** * Visits an enumeration value of the annotation. * * @param name the value name. * @param descriptor the class descriptor of the enumeration class. * @param value the actual enumeration value. */ public void visitEnum(final String name, final String descriptor, final String value) { if (av != null) { av.visitEnum(name, descriptor, value); } } /** * Visits a nested annotation value of the annotation. * * @param name the value name. * @param descriptor the class descriptor of the nested annotation class. * @return a visitor to visit the actual nested annotation value, or {@literal null} if this * visitor is not interested in visiting this nested annotation. <i>The nested annotation * value must be fully visited before calling other methods on this annotation visitor</i>. */ public AnnotationVisitor visitAnnotation(final String name, final String descriptor) { if (av != null) { return av.visitAnnotation(name, descriptor); } return null; } /** * Visits an array value of the annotation. Note that arrays of primitive types (such as byte, * boolean, short, char, int, long, float or double) can be passed as value to {@link #visit * visit}. This is what {@link ClassReader} does. * * @param name the value name. * @return a visitor to visit the actual array value elements, or {@literal null} if this visitor * is not interested in visiting these values. The 'name' parameters passed to the methods of * this visitor are ignored. <i>All the array values must be visited before calling other * methods on this annotation visitor</i>. */ public AnnotationVisitor visitArray(final String name) { if (av != null) { return av.visitArray(name); } return null; } /** Visits the end of the annotation. */ public void visitEnd() { if (av != null) { av.visitEnd(); } } }