1 /* 2 * Javassist, a Java-bytecode translator toolkit. 3 * Copyright (C) 1999-2007 Shigeru Chiba. All Rights Reserved. 4 * 5 * The contents of this file are subject to the Mozilla Public License Version 6 * 1.1 (the "License"); you may not use this file except in compliance with 7 * the License. Alternatively, the contents of this file may be used under 8 * the terms of the GNU Lesser General Public License Version 2.1 or later. 9 * 10 * Software distributed under the License is distributed on an "AS IS" basis, 11 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License 12 * for the specific language governing rights and limitations under the 13 * License. 14 */ 15 16 package javassist.bytecode; 17 18 import javassist.CtClass; 19 import javassist.bytecode.annotation.AnnotationsWriter; 20 import javassist.bytecode.annotation.MemberValue; 21 22 import java.io.ByteArrayOutputStream; 23 import java.io.DataInputStream; 24 import java.io.IOException; 25 import java.util.Map; 26 27 /** 28 * A class representing <code>AnnotationDefault_attribute</code>. 29 * 30 * <p>For example, if you declare the following annotation type: 31 * 32 * <ul><pre> 33 * @interface Author { 34 * String name() default "Shakespeare"; 35 * int age() default 99; 36 * } 37 * </pre></ul> 38 * 39 * <p>The defautl values of <code>name</code> and <code>age</code> 40 * are stored as annotation default attributes in <code>Author.class</code>. 41 * The following code snippet obtains the default value of <code>name</code>: 42 * 43 * <ul><pre> 44 * ClassPool pool = ... 45 * CtClass cc = pool.get("Author"); 46 * CtMethod cm = cc.getDeclaredMethod("age"); 47 * MethodInfo minfo = cm.getMethodInfo(); 48 * AnnotationDefaultAttribute ada 49 * = (AnnotationDefaultAttribute) 50 * minfo.getAttribute(AnnotationDefaultAttribute.tag); 51 * MemberValue value = ada.getDefaultValue()); // default value of age 52 * </pre></ul> 53 * 54 * <p>If the following statement is executed after the code above, 55 * the default value of age is set to 80: 56 * 57 * <ul><pre> 58 * ada.setDefaultValue(new IntegerMemberValue(minfo.getConstPool(), 80)); 59 * </pre></ul> 60 * 61 * @see AnnotationsAttribute 62 * @see javassist.bytecode.annotation.MemberValue 63 */ 64 65 public class AnnotationDefaultAttribute extends AttributeInfo { 66 /** 67 * The name of the <code>AnnotationDefault</code> attribute. 68 */ 69 public static final String tag = "AnnotationDefault"; 70 71 /** 72 * Constructs an <code>AnnotationDefault_attribute</code>. 73 * 74 * @param cp constant pool 75 * @param info the contents of this attribute. It does not 76 * include <code>attribute_name_index</code> or 77 * <code>attribute_length</code>. 78 */ 79 public AnnotationDefaultAttribute(ConstPool cp, byte[] info) { 80 super(cp, tag, info); 81 } 82 83 /** 84 * Constructs an empty <code>AnnotationDefault_attribute</code>. 85 * The default value can be set by <code>setDefaultValue()</code>. 86 * 87 * @param cp constant pool 88 * @see #setDefaultValue(javassist.bytecode.annotation.MemberValue) 89 */ 90 public AnnotationDefaultAttribute(ConstPool cp) { 91 this(cp, new byte[] { 0, 0 }); 92 } 93 94 /** 95 * @param n the attribute name. 96 */ 97 AnnotationDefaultAttribute(ConstPool cp, int n, DataInputStream in) 98 throws IOException 99 { 100 super(cp, n, in); 101 } 102 103 /** 104 * Copies this attribute and returns a new copy. 105 */ 106 public AttributeInfo copy(ConstPool newCp, Map classnames) { 107 AnnotationsAttribute.Copier copier 108 = new AnnotationsAttribute.Copier(info, constPool, newCp, classnames); 109 try { 110 copier.memberValue(0); 111 return new AnnotationDefaultAttribute(newCp, copier.close()); 112 } 113 catch (Exception e) { 114 throw new RuntimeException(e.toString()); 115 } 116 } 117 118 /** 119 * Obtains the default value represented by this attribute. 120 */ 121 public MemberValue getDefaultValue() 122 { 123 try { 124 return new AnnotationsAttribute.Parser(info, constPool) 125 .parseMemberValue(); 126 } 127 catch (Exception e) { 128 throw new RuntimeException(e.toString()); 129 } 130 } 131 132 /** 133 * Changes the default value represented by this attribute. 134 * 135 * @param value the new value. 136 * @see javassist.bytecode.annotation.Annotation#createMemberValue(ConstPool, CtClass) 137 */ 138 public void setDefaultValue(MemberValue value) { 139 ByteArrayOutputStream output = new ByteArrayOutputStream(); 140 AnnotationsWriter writer = new AnnotationsWriter(output, constPool); 141 try { 142 value.write(writer); 143 writer.close(); 144 } 145 catch (IOException e) { 146 throw new RuntimeException(e); // should never reach here. 147 } 148 149 set(output.toByteArray()); 150 151 } 152 153 /** 154 * Returns a string representation of this object. 155 */ 156 public String toString() { 157 return getDefaultValue().toString(); 158 } 159 } 160
