Java Code Examples for org.apache.bcel.Const#CONSTANT_Class

/**
 * Returns the indices of all class symbol references to {@code targetClassName} in the constant
 * pool of {@code sourceJavaClass}.
 */
ImmutableSet<Integer> constantPoolIndexForClass(
    JavaClass sourceJavaClass, String targetClassName) {
  ImmutableSet.Builder<Integer> constantPoolIndicesForTarget = ImmutableSet.builder();

  ConstantPool sourceConstantPool = sourceJavaClass.getConstantPool();
  Constant[] constantPool = sourceConstantPool.getConstantPool();
  // constantPool indexes start from 1. 0th entry is null.
  for (int poolIndex = 1; poolIndex < constantPool.length; poolIndex++) {
    Constant constant = constantPool[poolIndex];
    if (constant != null) {
      byte constantTag = constant.getTag();
      if (constantTag == Const.CONSTANT_Class) {
        ConstantClass constantClass = (ConstantClass) constant;
        ClassSymbol classSymbol = makeSymbol(constantClass, sourceConstantPool, sourceJavaClass);
        if (targetClassName.equals(classSymbol.getClassBinaryName())) {
          constantPoolIndicesForTarget.add(poolIndex);
        }
      }
    }
  }

  return constantPoolIndicesForTarget.build();
}
 

/**
 * Gets string from constant pool and bypass the indirection of
 * `ConstantClass' and `ConstantString' objects. I.e. these classes have
 * an index field that points to another entry of the constant pool of
 * type `ConstantUtf8' which contains the real data.
 *
 * @param  index Index in constant pool
 * @param  tag Tag of expected constant, either ConstantClass or ConstantString
 * @return Contents of string reference
 * @see    ConstantClass
 * @see    ConstantString
 * @throws  ClassFormatException
 */
public String getConstantString( final int index, final byte tag ) throws ClassFormatException {
    Constant c;
    int i;
    c = getConstant(index, tag);
    /* This switch() is not that elegant, since the four classes have the
     * same contents, they just differ in the name of the index
     * field variable.
     * But we want to stick to the JVM naming conventions closely though
     * we could have solved these more elegantly by using the same
     * variable name or by subclassing.
     */
    switch (tag) {
        case Const.CONSTANT_Class:
            i = ((ConstantClass) c).getNameIndex();
            break;
        case Const.CONSTANT_String:
            i = ((ConstantString) c).getStringIndex();
            break;
        case Const.CONSTANT_Module:
            i = ((ConstantModule) c).getNameIndex();
            break;
        case Const.CONSTANT_Package:
            i = ((ConstantPackage) c).getNameIndex();
            break;
        default:
            throw new IllegalArgumentException("getConstantString called with illegal tag " + tag);
    }
    // Finally get the string from the constant pool
    c = getConstant(i, Const.CONSTANT_Utf8);
    return ((ConstantUtf8) c).getBytes();
}
 

@Override
public void visitConstantClass(final ConstantClass obj) {
    if (obj.getTag() != Const.CONSTANT_Class) {
        throw new ClassConstraintException("Wrong constant tag in '"+tostring(obj)+"'.");
    }
    checkIndex(obj, obj.getNameIndex(), CONST_Utf8);

}
 

private static SymbolReferences.Builder findSymbolReferences(
    ClassFile source, JavaClass javaClass) {
  SymbolReferences.Builder builder = new SymbolReferences.Builder();

  ConstantPool constantPool = javaClass.getConstantPool();
  Constant[] constants = constantPool.getConstantPool();
  for (Constant constant : constants) {
    if (constant == null) {
       continue;
    }

    byte constantTag = constant.getTag();
    switch (constantTag) {
      case Const.CONSTANT_Class:
        ConstantClass constantClass = (ConstantClass) constant;
        ClassSymbol classSymbol = makeSymbol(constantClass, constantPool, javaClass);
        // skip array class because it is provided by runtime
        if (classSymbol.getClassBinaryName().startsWith("[")) {
          break;
        }
        builder.addClassReference(source, classSymbol);
        break;
      case Const.CONSTANT_Methodref:
      case Const.CONSTANT_InterfaceMethodref:
        // Both ConstantMethodref and ConstantInterfaceMethodref are subclass of ConstantCP
        ConstantCP constantMethodref = (ConstantCP) constant;
        builder.addMethodReference(source, makeSymbol(constantMethodref, constantPool));
        break;
      case Const.CONSTANT_Fieldref:
        ConstantFieldref constantFieldref = (ConstantFieldref) constant;
        builder.addFieldReference(source, makeSymbol(constantFieldref, constantPool));
        break;
      default:
        break;
    }
  }

  for (String interfaceName : javaClass.getInterfaceNames()) {
    builder.addClassReference(source, new InterfaceSymbol(interfaceName));
  }

  return builder;
}
 

public ConstantPool(JavaClass cls) {
    org.apache.bcel.classfile.ConstantPool cp = cls.getConstantPool();
   final int size = cp.getLength();
   add(new EmptyEntry(0)); // slot 0

   for (int i = 1; i < size; i++) {
      final Constant constant = cp.getConstant(i);
      if (constant != null) {
          final byte tag = constant.getTag();
          switch (tag) {
              case Const.CONSTANT_Class:
                  final int ni = ((ConstantClass) constant).getNameIndex();
                  add(new ClassEntry(ni, i));
                  break;
              case Const.CONSTANT_String:
                  final int si = ((ConstantString) constant).getStringIndex();
                  add(new StringEntry(si, i));
                  break;
              case Const.CONSTANT_Utf8:
                  add(new UTF8Entry(((ConstantUtf8) constant).getBytes(), i));
                  break;
              case Const.CONSTANT_Double:
                  add(new DoubleEntry(((ConstantDouble) constant).getBytes(), i));
                  break;
              case Const.CONSTANT_Float:
                  add(new FloatEntry(((ConstantFloat) constant).getBytes(), i));
                  break;
              case Const.CONSTANT_Long:
                  add(new LongEntry(((ConstantLong) constant).getBytes(), i));
                  break;
              case Const.CONSTANT_Integer:
                  add(new IntegerEntry(((ConstantInteger) constant).getBytes(), i));
                  break;
              case Const.CONSTANT_NameAndType:
                  final int ntInd = ((ConstantNameAndType) constant).getNameIndex();
                  final int siNT = ((ConstantNameAndType) constant).getSignatureIndex();
                  add(new NameAndTypeEntry(ntInd, siNT, i));
                  break;
              case Const.CONSTANT_InterfaceMethodref:
                  final int refClassIndexIMR = ((ConstantCP) constant).getClassIndex();
                  final int nameAndTypeIndIMR = ((ConstantCP) constant).getNameAndTypeIndex();
                  add(new InterfaceMethodEntry(refClassIndexIMR, nameAndTypeIndIMR, i));
                  break;
              case Const.CONSTANT_Methodref:
                  final int refClassIndexM = ((ConstantCP) constant).getClassIndex();
                  final int nameAndTypeIndM = ((ConstantCP) constant).getNameAndTypeIndex();
                  add(new MethodEntry(refClassIndexM, nameAndTypeIndM, i));
                  break;
              case Const.CONSTANT_Fieldref:
                  final int refClassIndex = ((ConstantCP) constant).getClassIndex();
                  final int nameAndTypeInd = ((ConstantCP) constant).getNameAndTypeIndex();
                  add(new FieldEntry(refClassIndex, nameAndTypeInd, i));
                  break;
              case Const.CONSTANT_MethodHandle:
                  final ConstantMethodHandle cmh = (ConstantMethodHandle) constant;
                  final int refKind = cmh.getReferenceKind();
                  final int refInd = cmh.getReferenceIndex();
                  add(new MethodHandleEntry(refKind, refInd, i));
                  break;
              case Const.CONSTANT_MethodType:
                  final ConstantMethodType cmt = (ConstantMethodType) constant;
                  final int descInd = cmt.getDescriptorIndex();
                  add(new MethodTypeEntry(descInd, i));
                  break;
              case Const.CONSTANT_InvokeDynamic:
                  final ConstantInvokeDynamic cid = (ConstantInvokeDynamic) constant;
                  final int bsMethAttInd = cid.getBootstrapMethodAttrIndex();
                  final int ntIndID = cid.getNameAndTypeIndex();
                  add(new InvokeDynamicEntry(bsMethAttInd, ntIndID, i));
                  break;
              default:
                  System.out.printf("slot %04x unexpected Constant constantPoolType = %s\n", i, constant);
          }
      } else {
          add(new EmptyEntry(i));
      }
   }
}
 

/**
 * Resolves constant to a string representation.
 *
 * @param  c Constant to be printed
 * @return String representation
 */
public String constantToString( Constant c ) throws ClassFormatException {
    String str;
    int i;
    final byte tag = c.getTag();
    switch (tag) {
        case Const.CONSTANT_Class:
            i = ((ConstantClass) c).getNameIndex();
            c = getConstant(i, Const.CONSTANT_Utf8);
            str = Utility.compactClassName(((ConstantUtf8) c).getBytes(), false);
            break;
        case Const.CONSTANT_String:
            i = ((ConstantString) c).getStringIndex();
            c = getConstant(i, Const.CONSTANT_Utf8);
            str = "\"" + escape(((ConstantUtf8) c).getBytes()) + "\"";
            break;
        case Const.CONSTANT_Utf8:
            str = ((ConstantUtf8) c).getBytes();
            break;
        case Const.CONSTANT_Double:
            str = String.valueOf(((ConstantDouble) c).getBytes());
            break;
        case Const.CONSTANT_Float:
            str = String.valueOf(((ConstantFloat) c).getBytes());
            break;
        case Const.CONSTANT_Long:
            str = String.valueOf(((ConstantLong) c).getBytes());
            break;
        case Const.CONSTANT_Integer:
            str = String.valueOf(((ConstantInteger) c).getBytes());
            break;
        case Const.CONSTANT_NameAndType:
            str = constantToString(((ConstantNameAndType) c).getNameIndex(),
                    Const.CONSTANT_Utf8)
                    + " " + constantToString(((ConstantNameAndType) c).getSignatureIndex(),
                    Const.CONSTANT_Utf8);
            break;
        case Const.CONSTANT_InterfaceMethodref:
        case Const.CONSTANT_Methodref:
        case Const.CONSTANT_Fieldref:
            str = constantToString(((ConstantCP) c).getClassIndex(), Const.CONSTANT_Class)
                    + "." + constantToString(((ConstantCP) c).getNameAndTypeIndex(),
                    Const.CONSTANT_NameAndType);
            break;
        case Const.CONSTANT_MethodHandle:
            // Note that the ReferenceIndex may point to a Fieldref, Methodref or
            // InterfaceMethodref - so we need to peek ahead to get the actual type.
            final ConstantMethodHandle cmh = (ConstantMethodHandle) c;
            str = Const.getMethodHandleName(cmh.getReferenceKind())
                    + " " + constantToString(cmh.getReferenceIndex(),
                    getConstant(cmh.getReferenceIndex()).getTag());
            break;
        case Const.CONSTANT_MethodType:
            final ConstantMethodType cmt = (ConstantMethodType) c;
            str = constantToString(cmt.getDescriptorIndex(), Const.CONSTANT_Utf8);
            break;
        case Const.CONSTANT_InvokeDynamic:
            final ConstantInvokeDynamic cid = (ConstantInvokeDynamic) c;
            str = cid.getBootstrapMethodAttrIndex()
                    + ":" + constantToString(cid.getNameAndTypeIndex(),
                    Const.CONSTANT_NameAndType);
            break;
        case Const.CONSTANT_Module:
            i = ((ConstantModule) c).getNameIndex();
            c = getConstant(i, Const.CONSTANT_Utf8);
            str = Utility.compactClassName(((ConstantUtf8) c).getBytes(), false);
            break;
        case Const.CONSTANT_Package:
            i = ((ConstantPackage) c).getNameIndex();
            c = getConstant(i, Const.CONSTANT_Utf8);
            str = Utility.compactClassName(((ConstantUtf8) c).getBytes(), false);
            break;
        default: // Never reached
            throw new IllegalArgumentException("Unknown constant type " + tag);
    }
    return str;
}
 

/**
 * Reads one constant from the given input, the type depends on a tag byte.
 *
 * @param dataInput Input stream
 * @return Constant object
 * @throws IOException if an I/O error occurs reading from the given {@code dataInput}.
 * @throws ClassFormatException if the next byte is not recognized
 * @since 6.0 made public
 */
public static Constant readConstant(final DataInput dataInput) throws IOException, ClassFormatException {
    final byte b = dataInput.readByte(); // Read tag byte
    switch (b) {
    case Const.CONSTANT_Class:
        return new ConstantClass(dataInput);
    case Const.CONSTANT_Fieldref:
        return new ConstantFieldref(dataInput);
    case Const.CONSTANT_Methodref:
        return new ConstantMethodref(dataInput);
    case Const.CONSTANT_InterfaceMethodref:
        return new ConstantInterfaceMethodref(dataInput);
    case Const.CONSTANT_String:
        return new ConstantString(dataInput);
    case Const.CONSTANT_Integer:
        return new ConstantInteger(dataInput);
    case Const.CONSTANT_Float:
        return new ConstantFloat(dataInput);
    case Const.CONSTANT_Long:
        return new ConstantLong(dataInput);
    case Const.CONSTANT_Double:
        return new ConstantDouble(dataInput);
    case Const.CONSTANT_NameAndType:
        return new ConstantNameAndType(dataInput);
    case Const.CONSTANT_Utf8:
        return ConstantUtf8.getInstance(dataInput);
    case Const.CONSTANT_MethodHandle:
        return new ConstantMethodHandle(dataInput);
    case Const.CONSTANT_MethodType:
        return new ConstantMethodType(dataInput);
    case Const.CONSTANT_Dynamic:
        return new ConstantDynamic(dataInput);
    case Const.CONSTANT_InvokeDynamic:
        return new ConstantInvokeDynamic(dataInput);
    case Const.CONSTANT_Module:
        return new ConstantModule(dataInput);
    case Const.CONSTANT_Package:
        return new ConstantPackage(dataInput);
    default:
        throw new ClassFormatException("Invalid byte tag in constant pool: " + b);
    }
}
 

/**
 * @param nameIndex Name index in constant pool.  Should refer to a
 * ConstantUtf8.
 */
public ConstantClass(final int nameIndex) {
    super(Const.CONSTANT_Class);
    this.nameIndex = nameIndex;
}