annotationsattribute.java

Javassist是一个开源的分析、编辑和创建Java字节码的类库。是由东京技术学院的数学和计算机科学系的 Shigeru Chiba 所创建的。它已加入了开放源代码JBoss 应用服务器项目,通过使

        int annotationArray(int pos, int num) throws Exception {
            for (int i = 0; i < num; ++i)
                pos = annotation(pos);

            return pos;
        }

        final int annotation(int pos) throws Exception {
            int type = ByteArray.readU16bit(info, pos);
            int numPairs = ByteArray.readU16bit(info, pos + 2);
            return annotation(pos + 4, type, numPairs);
        }

        int annotation(int pos, int type, int numPairs) throws Exception {
            for (int j = 0; j < numPairs; ++j)
                pos = memberValuePair(pos);

            return pos;
        }

        final int memberValuePair(int pos) throws Exception {
            int nameIndex = ByteArray.readU16bit(info, pos);
            return memberValuePair(pos + 2, nameIndex);
        }

        int memberValuePair(int pos, int nameIndex) throws Exception {
            return memberValue(pos);
        }

        final int memberValue(int pos) throws Exception {
            int tag = info[pos] & 0xff;
            if (tag == 'e') {
                int typeNameIndex = ByteArray.readU16bit(info, pos + 1);
                int constNameIndex = ByteArray.readU16bit(info, pos + 3);
                enumMemberValue(typeNameIndex, constNameIndex);
                return pos + 5;
            }
            else if (tag == 'c') {
                int index = ByteArray.readU16bit(info, pos + 1);
                classMemberValue(index);
                return pos + 3;
            }
            else if (tag == '@')
                return annotationMemberValue(pos + 1);
            else if (tag == '[') {
                int num = ByteArray.readU16bit(info, pos + 1);
                return arrayMemberValue(pos + 3, num);
            }
            else { // primitive types or String.
                int index = ByteArray.readU16bit(info, pos + 1);
                constValueMember(tag, index);
                return pos + 3;
            }
        }

        void constValueMember(int tag, int index) throws Exception {}

        void enumMemberValue(int typeNameIndex, int constNameIndex)
            throws Exception {
        }

        void classMemberValue(int index) throws Exception {}

        int annotationMemberValue(int pos) throws Exception {
            return annotation(pos);
        }

        int arrayMemberValue(int pos, int num) throws Exception {
            for (int i = 0; i < num; ++i) {
                pos = memberValue(pos);
            }

            return pos;
        }
    }

    static class Copier extends Walker {
        ByteArrayOutputStream output;
        AnnotationsWriter writer;
        ConstPool srcPool, destPool;
        Map classnames;

        /**
         * Constructs a copier.  This copier renames some class names
         * into the new names specified by <code>map</code> when it copies
         * an annotation attribute.
         *
         * @param info      the source attribute.
         * @param src       the constant pool of the source class.
         * @param dest      the constant pool of the destination class.
         * @param map       pairs of replaced and substituted class names.
         *                  It can be null.
         */
        Copier(byte[] info, ConstPool src, ConstPool dest, Map map) {
            super(info);
            output = new ByteArrayOutputStream();
            writer = new AnnotationsWriter(output, dest);
            srcPool = src;
            destPool = dest;
            classnames = map;
        }

        byte[] close() throws IOException {
            writer.close();
            return output.toByteArray();
        }

        void parameters(int numParam, int pos) throws Exception {
            writer.numParameters(numParam);
            super.parameters(numParam, pos);
        }

        int annotationArray(int pos, int num) throws Exception {
            writer.numAnnotations(num);
            return super.annotationArray(pos, num);
        }

        int annotation(int pos, int type, int numPairs) throws Exception {
            writer.annotation(copy(type), numPairs);
            return super.annotation(pos, type, numPairs);
        }

        int memberValuePair(int pos, int nameIndex) throws Exception {
            writer.memberValuePair(copy(nameIndex));
            return super.memberValuePair(pos, nameIndex);
        }

        void constValueMember(int tag, int index) throws Exception {
            writer.constValueIndex(tag, copy(index));
            super.constValueMember(tag, index);
        }

        void enumMemberValue(int typeNameIndex, int constNameIndex)
            throws Exception
        {
            writer.enumConstValue(copy(typeNameIndex), copy(constNameIndex));
            super.enumMemberValue(typeNameIndex, constNameIndex);
        }

        void classMemberValue(int index) throws Exception {
            writer.classInfoIndex(copy(index));
            super.classMemberValue(index);
        }

        int annotationMemberValue(int pos) throws Exception {
            writer.annotationValue();
            return super.annotationMemberValue(pos);
        }

        int arrayMemberValue(int pos, int num) throws Exception {
            writer.arrayValue(num);
            return super.arrayMemberValue(pos, num);
        }

        /**
         * Copies a constant pool entry into the destination constant pool
         * and returns the index of the copied entry.
         *
         * @param srcIndex      the index of the copied entry into the source
         *                      constant pool.
         * @return the index of the copied item into the destination
         *         constant pool.
         */
        int copy(int srcIndex) {
            return srcPool.copy(srcIndex, destPool, classnames);
        }
    }

    static class Parser extends Walker {
        ConstPool pool;
        Annotation[][] allParams;   // all parameters
        Annotation[] allAnno;       // all annotations
        Annotation currentAnno;     // current annotation
        MemberValue currentMember;  // current member

        /**
         * Constructs a parser.  This parser constructs a parse tree of
         * the annotations.
         *
         * @param info      the attribute.
         * @param src       the constant pool.
         */
        Parser(byte[] info, ConstPool cp) {
            super(info);
            pool = cp;
        }

        Annotation[][] parseParameters() throws Exception {
            parameters();
            return allParams;
        }

        Annotation[] parseAnnotations() throws Exception {
            annotationArray();
            return allAnno;
        }

        MemberValue parseMemberValue() throws Exception {
            memberValue(0);
            return currentMember;
        }

        void parameters(int numParam, int pos) throws Exception {
            Annotation[][] params = new Annotation[numParam][];
            for (int i = 0; i < numParam; ++i) {
                pos = annotationArray(pos);
                params[i] = allAnno;
            }

            allParams = params;
        }

        int annotationArray(int pos, int num) throws Exception {
            Annotation[] array = new Annotation[num];
            for (int i = 0; i < num; ++i) {
                pos = annotation(pos);
                array[i] = currentAnno;
            }

            allAnno = array;
            return pos;
        }

        int annotation(int pos, int type, int numPairs) throws Exception {
            currentAnno = new Annotation(type, pool);
            return super.annotation(pos, type, numPairs);
        }

        int memberValuePair(int pos, int nameIndex) throws Exception {
            pos = super.memberValuePair(pos, nameIndex);
            currentAnno.addMemberValue(nameIndex, currentMember);
            return pos;
        }

        void constValueMember(int tag, int index) throws Exception {
            MemberValue m;
            ConstPool cp = pool;
            switch (tag) {
            case 'B' :
                m = new ByteMemberValue(index, cp);
                break;
            case 'C' :
                m = new CharMemberValue(index, cp);
                break;
            case 'D' :
                m = new DoubleMemberValue(index, cp);
                break;
            case 'F' :
                m = new FloatMemberValue(index, cp);
                break;
            case 'I' :
                m = new IntegerMemberValue(index, cp);
                break;
            case 'J' :
                m = new LongMemberValue(index, cp);
                break;
            case 'S' :
                m = new ShortMemberValue(index, cp);
                break;
            case 'Z' :
                m = new BooleanMemberValue(index, cp);
                break;
            case 's' :
                m = new StringMemberValue(index, cp);
                break;
            default :
                throw new RuntimeException("unknown tag:" + tag);
            }

            currentMember = m;
            super.constValueMember(tag, index);
        }

        void enumMemberValue(int typeNameIndex, int constNameIndex)
            throws Exception
        {
            currentMember = new EnumMemberValue(typeNameIndex,
                                              constNameIndex, pool);
            super.enumMemberValue(typeNameIndex, constNameIndex);
        }

        void classMemberValue(int index) throws Exception {
            currentMember = new ClassMemberValue(index, pool);
            super.classMemberValue(index);
        }

        int annotationMemberValue(int pos) throws Exception {
            Annotation anno = currentAnno;
            pos = super.annotationMemberValue(pos);
            currentMember = new AnnotationMemberValue(currentAnno, pool);
            currentAnno = anno;
            return pos;
        }

        int arrayMemberValue(int pos, int num) throws Exception {
            ArrayMemberValue amv = new ArrayMemberValue(pool);
            MemberValue[] elements = new MemberValue[num];
            for (int i = 0; i < num; ++i) {
                pos = memberValue(pos);
                elements[i] = currentMember;
            }

            amv.setValue(elements);
            currentMember = amv;
            return pos;
        }
    }
}