Class Descriptor

java.lang.Object
javassist.bytecode.Descriptor
public class Descriptor extends Object
A support class for dealing with descriptors.

See chapter 4.3 in "The Java Virtual Machine Specification (2nd ed.)"

  • Constructor Details

    • Descriptor

      public Descriptor()

  • Method Details

    • toJvmName

      public static String toJvmName(String classname)
      Converts a class name into the internal representation used in the JVM.

      Note that toJvmName(toJvmName(s)) is equivalent to toJvmName(s).

    • toJavaName

      public static String toJavaName(String classname)
      Converts a class name from the internal representation used in the JVM to the normal one used in Java. This method does not deal with an array type name such as "[Ljava/lang/Object;" and "[I;". For such names, use toClassName().
      See Also:

    • toJvmName

      public static String toJvmName(CtClass clazz)
      Returns the internal representation of the class name in the JVM.

    • toClassName

      public static String toClassName(String descriptor)
      Converts to a Java class name from a descriptor.
      Parameters:
      descriptor - type descriptor.

    • of

      public static String of(String classname)
      Converts to a descriptor from a Java class name

    • rename

      public static String rename(String desc, String oldname, String newname)
      Substitutes a class name in the given descriptor string.
      Parameters:
      desc - descriptor string
      oldname - replaced JVM class name
      newname - substituted JVM class name
      See Also:

    • rename

      public static String rename(String desc, Map<String,String> map)
      Substitutes class names in the given descriptor string according to the given map.
      Parameters:
      map - a map between replaced and substituted JVM class names.
      See Also:

    • of

      public static String of(CtClass type)
      Returns the descriptor representing the given type.

    • ofConstructor

      public static String ofConstructor(CtClass[] paramTypes)
      Returns the descriptor representing a constructor receiving the given parameter types.
      Parameters:
      paramTypes - parameter types

    • ofMethod

      public static String ofMethod(CtClass returnType, CtClass[] paramTypes)
      Returns the descriptor representing a method that receives the given parameter types and returns the given type.
      Parameters:
      returnType - return type
      paramTypes - parameter types

    • ofParameters

      public static String ofParameters(CtClass[] paramTypes)
      Returns the descriptor representing a list of parameter types. For example, if the given parameter types are two int, then this method returns "(II)".
      Parameters:
      paramTypes - parameter types

    • appendParameter

      public static String appendParameter(String classname, String desc)
      Appends a parameter type to the parameter list represented by the given descriptor.

      classname must not be an array type.

      Parameters:
      classname - parameter type (not primitive type)
      desc - descriptor

    • insertParameter

      public static String insertParameter(String classname, String desc)
      Inserts a parameter type at the beginning of the parameter list represented by the given descriptor.

      classname must not be an array type.

      Parameters:
      classname - parameter type (not primitive type)
      desc - descriptor

    • appendParameter

      public static String appendParameter(CtClass type, String descriptor)
      Appends a parameter type to the parameter list represented by the given descriptor. The appended parameter becomes the last parameter.
      Parameters:
      type - the type of the appended parameter.
      descriptor - the original descriptor.

    • insertParameter

      public static String insertParameter(CtClass type, String descriptor)
      Inserts a parameter type at the beginning of the parameter list represented by the given descriptor.
      Parameters:
      type - the type of the inserted parameter.
      descriptor - the descriptor of the method.

    • changeReturnType

      public static String changeReturnType(String classname, String desc)
      Changes the return type included in the given descriptor.

      classname must not be an array type.

      Parameters:
      classname - return type
      desc - descriptor

    • getParameterTypes

      public static CtClass[] getParameterTypes(String desc, ClassPool cp) throws NotFoundException
      Returns the CtClass objects representing the parameter types specified by the given descriptor.
      Parameters:
      desc - descriptor
      cp - the class pool used for obtaining a CtClass object.
      Throws:
      NotFoundException

    • eqParamTypes

      public static boolean eqParamTypes(String desc1, String desc2)
      Returns true if the list of the parameter types of desc1 is equal to that of desc2. For example, "(II)V" and "(II)I" are equal.

    • getParamDescriptor

      public static String getParamDescriptor(String decl)
      Returns the signature of the given descriptor. The signature does not include the return type. For example, the signature of "(I)V" is "(I)".

    • getReturnType

      public static CtClass getReturnType(String desc, ClassPool cp) throws NotFoundException
      Returns the CtClass object representing the return type specified by the given descriptor.
      Parameters:
      desc - descriptor
      cp - the class pool used for obtaining a CtClass object.
      Throws:
      NotFoundException

    • numOfParameters

      public static int numOfParameters(String desc)
      Returns the number of the prameters included in the given descriptor.
      Parameters:
      desc - descriptor

    • toCtClass

      public static CtClass toCtClass(String desc, ClassPool cp) throws NotFoundException
      Returns a CtClass object representing the type specified by the given descriptor.

      This method works even if the package-class separator is not / but . (period). For example, it accepts Ljava.lang.Object; as well as Ljava/lang/Object;.

      Parameters:
      desc - descriptor.
      cp - the class pool used for obtaining a CtClass object.
      Throws:
      NotFoundException

    • arrayDimension

      public static int arrayDimension(String desc)
      Computes the dimension of the array represented by the given descriptor. For example, if the descriptor is "[[I", then this method returns 2.
      Parameters:
      desc - the descriptor.
      Returns:
      0 if the descriptor does not represent an array type.

    • toArrayComponent

      public static String toArrayComponent(String desc, int dim)
      Returns the descriptor of the type of the array component. For example, if the given descriptor is "[[Ljava/lang/String;" and the given dimension is 2, then this method returns "Ljava/lang/String;".
      Parameters:
      desc - the descriptor.
      dim - the array dimension.

    • dataSize

      public static int dataSize(String desc)
      Computes the data size specified by the given descriptor. For example, if the descriptor is "D", this method returns 2.

      If the descriptor represents a method type, this method returns (the size of the returned value) - (the sum of the data sizes of all the parameters). For example, if the descriptor is "(I)D", then this method returns 1 (= 2 - 1).

      Parameters:
      desc - descriptor

    • paramSize

      public static int paramSize(String desc)
      Computes the data size of parameters. If one of the parameters is double type, the size of that parameter is 2 words. For example, if the given descriptor is "(IJ)D", then this method returns 3. The size of the return type is not computed.
      Parameters:
      desc - a method descriptor.

    • toString

      public static String toString(String desc)
      Returns a human-readable representation of the given descriptor. For example, Ljava/lang/Object; is converted into java.lang.Object. (I[I)V is converted into (int, int[]) (the return type is ignored).