Class Utility

java.lang.Object
org.apache.bcel.classfile.Utility
public abstract class Utility extends Object
Utility functions that do not really belong to any class in particular.

  • Constructor Details

    • Utility

      public Utility()
      Deprecated.
      Will be private in the next major release.
      Constructs a Utility.

  • Method Details

    • accessToString

      public static String accessToString(int accessFlags)
      Convert bit field of flags into string such as 'static final'.
      Parameters:
      accessFlags - Access flags.
      Returns:
      String representation of flags.

    • accessToString

      public static String accessToString(int accessFlags, boolean forClass)
      Convert bit field of flags into string such as 'static final'.

      Special case: Classes compiled with new compilers and with the 'ACC_SUPER' flag would be said to be "synchronized". This is because SUN used the same value for the flags 'ACC_SUPER' and 'ACC_SYNCHRONIZED'.

      Parameters:
      accessFlags - Access flags.
      forClass - access flags are for class qualifiers ?.
      Returns:
      String representation of flags.

    • classOrInterface

      public static String classOrInterface(int accessFlags)
      Gets the class or interface type name.
      Parameters:
      accessFlags - The class flags.
      Returns:
      "class" or "interface", depending on the ACC_INTERFACE flag.

    • clearBit

      public static int clearBit(int flag, int i)
      Clears a bit in a flag.
      Parameters:
      flag - The flag value.
      i - The bit position.
      Returns:
      'flag' with bit 'i' set to 0.

    • codeToString

      public static String codeToString(byte[] code, ConstantPool constantPool, int index, int length)
      Disassembles byte code.
      Parameters:
      code - byte code array.
      constantPool - The constant pool.
      index - offset in code array.
      length - number of opcodes to decompile.
      Returns:
      disassembled string representation.

    • codeToString

      public static String codeToString(byte[] code, ConstantPool constantPool, int index, int length, boolean verbose)
      Disassemble a byte array of JVM byte codes starting from code line 'index' and return the disassembled string representation. Decode only 'num' opcodes (including their operands), use -1 if you want to decompile everything.
      Parameters:
      code - byte code array.
      constantPool - Array of constants.
      index - offset in 'code' array (number of opcodes, not bytes!).
      length - number of opcodes to decompile, -1 for all.
      verbose - be verbose, for example print constant pool index.
      Returns:
      String representation of byte codes.

    • codeToString

      public static String codeToString(ByteSequence bytes, ConstantPool constantPool) throws IOException
      Disassembles byte code.
      Parameters:
      bytes - stream of bytes.
      constantPool - The constant pool.
      Returns:
      disassembled string representation.
      Throws:
      IOException - Thrown if a failure from reading from the bytes argument occurs.

    • codeToString

      public static String codeToString(ByteSequence bytes, ConstantPool constantPool, boolean verbose) throws IOException
      Disassemble a stream of byte codes and return the string representation.
      Parameters:
      bytes - stream of bytes.
      constantPool - Array of constants.
      verbose - be verbose, for example print constant pool index.
      Returns:
      String representation of byte code.
      Throws:
      IOException - Thrown if a failure from reading from the bytes argument occurs

    • compactClassName

      public static String compactClassName(String str)
      Shorten long class names, java/lang/String becomes String.
      Parameters:
      str - The long class name.
      Returns:
      Compacted class name.

    • compactClassName

      public static String compactClassName(String str, boolean chopit)
      Shorten long class names, java/lang/String becomes java.lang.String, for example. If chopit is true the prefix java.lang is also removed.
      Parameters:
      str - The long class name.
      chopit - flag that determines whether chopping is executed or not.
      Returns:
      Compacted class name.

    • compactClassName

      public static String compactClassName(String str, String prefix, boolean chopit)
      Shorten long class name str, that is, chop off the prefix, if the class name starts with this string and the flag chopit is true. Slashes / are converted to dots ..
      Parameters:
      str - The long class name.
      prefix - The prefix the get rid off.
      chopit - flag that determines whether chopping is executed or not.
      Returns:
      Compacted class name.

    • convertString

      public static String convertString(String label)
      Escape all occurrences of newline chars '\n', quotes \", etc.
      Parameters:
      label - The string to convert.
      Returns:
      The converted string.

    • decode

      public static byte[] decode(String s, boolean uncompress) throws IOException
      Decode a string back to a byte array.
      Parameters:
      s - The string to convert.
      uncompress - use gzip to uncompress the stream of bytes.
      Returns:
      The decoded byte array.
      Throws:
      IOException - Thrown if there's a gzip exception or the decompressed data exceeds MAX_DECODED_LENGTH.

    • encode

      public static String encode(byte[] bytes, boolean compress) throws IOException
      Encode byte array it into Java identifier string, that is, a string that only contains the following characters: (a, ... z, A, ... Z, 0, ... 9, _, $). The encoding algorithm itself is not too clever: if the current byte's ASCII value already is a valid Java identifier part, leave it as it is. Otherwise it writes the escape character($) followed by:
      • the ASCII value as a hexadecimal string, if the value is not in the range 200..247
      • a Java identifier char not used in a lowercase hexadecimal string, if the value is in the range 200..247

      This operation inflates the original byte array by roughly 40-50%

      Parameters:
      bytes - The byte array to convert.
      compress - use gzip to minimize string.
      Returns:
      The encoded string.
      Throws:
      IOException - Thrown if there's a gzip exception.

    • fillup

      public static String fillup(String str, int length, boolean leftJustify, char fill)
      Fillup char with up to length characters with char 'fill' and justify it left or right.
      Parameters:
      str - string to format.
      length - length of desired string.
      leftJustify - format left or right.
      fill - fill character.
      Returns:
      formatted string.

    • format

      public static String format(int i, int length, boolean leftJustify, char fill)
      Return a string for an integer justified left or right and filled up with 'fill' characters if necessary.
      Parameters:
      i - integer to format.
      length - length of desired string.
      leftJustify - format left or right.
      fill - fill character.
      Returns:
      formatted int.

    • getSignature

      public static String getSignature(String type)
      Parse Java type such as "char", or "java.lang.String[]" and return the signature in byte code format, for example "C" or "[Ljava/lang/String;" respectively.
      Parameters:
      type - Java type.
      Returns:
      byte code signature.

    • isJavaIdentifierPart

      public static boolean isJavaIdentifierPart(char ch)
      Tests if a character is part of a Java identifier.
      Parameters:
      ch - The character to test if it's part of an identifier.
      Returns:
      true, if character is one of (a, ... z, A, ... Z, 0, ... 9, _).

    • isSet

      public static boolean isSet(int flag, int i)
      Tests if a bit is set.
      Parameters:
      flag - The flag value.
      i - The bit position.
      Returns:
      true, if bit 'i' in 'flag' is set.

    • methodSignatureArgumentTypes

      public static String[] methodSignatureArgumentTypes(String signature) throws ClassFormatException
      Converts argument list portion of method signature to string with all class names compacted.
      Parameters:
      signature - Method signature.
      Returns:
      String Array of argument types.
      Throws:
      ClassFormatException - Thrown if a class is malformed or cannot be interpreted as a class file

    • methodSignatureArgumentTypes

      public static String[] methodSignatureArgumentTypes(String signature, boolean chopit) throws ClassFormatException
      Converts argument list portion of method signature to string.
      Parameters:
      signature - Method signature.
      chopit - flag that determines whether chopping is executed or not.
      Returns:
      String Array of argument types.
      Throws:
      ClassFormatException - Thrown if a class is malformed or cannot be interpreted as a class file

    • methodSignatureReturnType

      public static String methodSignatureReturnType(String signature) throws ClassFormatException
      Converts return type portion of method signature to string with all class names compacted.
      Parameters:
      signature - Method signature.
      Returns:
      String representation of method return type.
      Throws:
      ClassFormatException - Thrown if a class is malformed or cannot be interpreted as a class file

    • methodSignatureReturnType

      public static String methodSignatureReturnType(String signature, boolean chopit) throws ClassFormatException
      Converts return type portion of method signature to string.
      Parameters:
      signature - Method signature.
      chopit - flag that determines whether chopping is executed or not.
      Returns:
      String representation of method return type.
      Throws:
      ClassFormatException - Thrown if a class is malformed or cannot be interpreted as a class file

    • methodSignatureToString

      public static String methodSignatureToString(String signature, String name, String access)
      Converts method signature to string with all class names compacted.
      Parameters:
      signature - to convert.
      name - of method.
      access - flags of method.
      Returns:
      Human readable signature.

    • methodSignatureToString

      public static String methodSignatureToString(String signature, String name, String access, boolean chopit)
      Converts method signature to string.
      Parameters:
      signature - to convert.
      name - of method.
      access - flags of method.
      chopit - flag that determines whether chopping is executed or not.
      Returns:
      Human readable signature.

    • methodSignatureToString

      public static String methodSignatureToString(String signature, String name, String access, boolean chopit, LocalVariableTable vars) throws ClassFormatException
      This method converts a method signature string into a Java type declaration like 'void main(String[])' and throws a 'ClassFormatException' when the parsed type is invalid.
      Parameters:
      signature - Method signature.
      name - Method name.
      access - Method access rights.
      chopit - flag that determines whether chopping is executed or not.
      vars - The LocalVariableTable for the method.
      Returns:
      Java type declaration.
      Throws:
      ClassFormatException - Thrown if a class is malformed or cannot be interpreted as a class file

    • methodTypeToSignature

      public static String methodTypeToSignature(String ret, String[] argv) throws ClassFormatException
      Converts string containing the method return and argument types to a byte code method signature.
      Parameters:
      ret - Return type of method.
      argv - Types of method arguments.
      Returns:
      Byte code representation of method signature.
      Throws:
      ClassFormatException - Thrown if the signature is for Void

    • packageToPath

      public static String packageToPath(String name)
      Converts '.'s to '/'s.
      Parameters:
      name - Source.
      Returns:
      converted value.
      Since:
      6.7.0

    • pathToPackage

      public static String pathToPackage(String str)
      Converts a path to a package name.
      Parameters:
      str - The source path.
      Returns:
      A package name.
      Since:
      6.6.0

    • printArray

      public static String printArray(Object[] obj)
      Prints an array to a string.
      Parameters:
      obj - The array to print.
      Returns:
      The string representation.

    • printArray

      public static String printArray(Object[] obj, boolean braces)
      Prints an array to a string.
      Parameters:
      obj - The array to print.
      braces - whether to include braces.
      Returns:
      The string representation.

    • printArray

      public static String printArray(Object[] obj, boolean braces, boolean quote)
      Prints an array to a string.
      Parameters:
      obj - The array to print.
      braces - whether to include braces.
      quote - whether to quote elements.
      Returns:
      The string representation.

    • printArray

      public static void printArray(PrintStream out, Object[] obj)
      Prints an array to a stream.
      Parameters:
      out - The output stream.
      obj - The array to print.

    • printArray

      public static void printArray(PrintWriter out, Object[] obj)
      Prints an array to a writer.
      Parameters:
      out - The output writer.
      obj - The array to print.

    • replace

      public static String replace(String str, String old, String new_)
      Replace all occurrences of old in str with new.
      Parameters:
      str - String to permute.
      old - String to be replaced.
      new_ - Replacement string.
      Returns:
      new String object.

    • searchOpcode

      public static short searchOpcode(String name)
      Map opcode names to opcode numbers. E.g., return Constants.ALOAD for "aload".
      Parameters:
      name - The opcode name.
      Returns:
      The value.

    • setBit

      public static int setBit(int flag, int i)
      Sets a bit in a flag.
      Parameters:
      flag - The flag value.
      i - The bit position.
      Returns:
      'flag' with bit 'i' set to 1.

    • signatureToString

      public static String signatureToString(String signature)
      Converts a signature to a string with all class names compacted. Class, Method and Type signatures are supported. Enum and Interface signatures are not supported.
      Parameters:
      signature - signature to convert.
      Returns:
      String containg human readable signature.

    • signatureToString

      public static String signatureToString(String signature, boolean chopit)
      Converts a signature to a string. Class, Method and Type signatures are supported. Enum and Interface signatures are not supported.
      Parameters:
      signature - signature to convert.
      chopit - flag that determines whether chopping is executed or not.
      Returns:
      String containg human readable signature.

    • toHexString

      public static String toHexString(byte[] bytes)
      Convert bytes into hexadecimal string
      Parameters:
      bytes - An array of bytes to convert to hexadecimal.
      Returns:
      bytes as hexadecimal string, for example 00 fa 12 ...

    • typeOfMethodSignature

      public static byte typeOfMethodSignature(String signature) throws ClassFormatException
      Return type of method signature as a byte value as defined in Constants
      Parameters:
      signature - in format described above.
      Returns:
      type of method signature.
      Throws:
      ClassFormatException - Thrown if signature is not a method signature
      See Also:

    • typeOfSignature

      public static byte typeOfSignature(String signature) throws ClassFormatException
      Return type of signature as a byte value as defined in Constants
      Parameters:
      signature - in format described above.
      Returns:
      type of signature.
      Throws:
      ClassFormatException - Thrown if signature isn't a known type
      See Also:

    • typeSignatureToString

      public static String typeSignatureToString(String signature, boolean chopit) throws ClassFormatException
      This method converts a type signature string into a Java type declaration such as 'String[]' and throws a 'ClassFormatException' when the parsed type is invalid.
      Parameters:
      signature - type signature.
      chopit - flag that determines whether chopping is executed or not.
      Returns:
      string containing human readable type signature.
      Throws:
      ClassFormatException - Thrown if a class is malformed or cannot be interpreted as a class file
      Since:
      6.4.0