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bcel API: Class Utility
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org.apache.bcel.classfile
Class Utility

java.lang.Object
  |
  +--org.apache.bcel.classfile.Utility
public abstract class Utility
extends java.lang.Object

Utility functions that do not really belong to any class in particular.

Version:
$Id: Utility.java,v 1.1.1.1 2001/10/29 20:00:05 jvanzyl Exp $
Author:
M. Dahm

Constructor Summary
Utility()
           
 
Method Summary
static java.lang.String accessToString(int access_flags)
          Convert bit field of flags into string such as `static final'.
static java.lang.String accessToString(int access_flags, boolean for_class)
          Convert bit field of flags into string such as `static final'.
static java.lang.String classOrInterface(int access_flags)
           
static int clearBit(int flag, int i)
           
static java.lang.String codeToString(byte[] code, ConstantPool constant_pool, int index, int length)
           
static java.lang.String codeToString(byte[] code, ConstantPool constant_pool, 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.
static java.lang.String codeToString(ByteSequence bytes, ConstantPool constant_pool)
           
static java.lang.String codeToString(ByteSequence bytes, ConstantPool constant_pool, boolean verbose)
          Disassemble a stream of byte codes and return the string representation.
static java.lang.String compactClassName(java.lang.String str)
          Shorten long class names, java/lang/String becomes String.
static java.lang.String compactClassName(java.lang.String str, boolean chopit)
          Shorten long class names, java/lang/String becomes java.lang.String, e.g..
static java.lang.String compactClassName(java.lang.String str, java.lang.String prefix, boolean chopit)
          Shorten long class name str, i.e., chop off the prefix, if the class name starts with this string and the flag chopit is true.
static byte[] decode(java.lang.String s, boolean uncompress)
          Decode a string back to a byte array.
static java.lang.String encode(byte[] bytes, boolean compress)
          Encode byte array it into Java identifier string, i.e., a string that only contains the following characters: (a, ...
static java.lang.String fillup(java.lang.String str, int length, boolean left_justify, char fill)
          Fillup char with up to length characters with char `fill' and justify it left or right.
static java.lang.String format(int i, int length, boolean left_justify, char fill)
          Return a string for an integer justified left or right and filled up with `fill' characters if necessary.
static java.lang.String getSignature(java.lang.String type)
          Parse Java type such as "char", or "java.lang.String[]" and return the signature in byte code format, e.g.
static boolean isJavaIdentifierPart(char ch)
           
static boolean isSet(int flag, int i)
           
static java.lang.String[] methodSignatureArgumentTypes(java.lang.String signature)
           
static java.lang.String[] methodSignatureArgumentTypes(java.lang.String signature, boolean chopit)
           
static java.lang.String methodSignatureReturnType(java.lang.String signature)
           
static java.lang.String methodSignatureReturnType(java.lang.String signature, boolean chopit)
           
static java.lang.String methodSignatureToString(java.lang.String signature, java.lang.String name, java.lang.String access)
          Converts method signature to string with all class names compacted.
static java.lang.String methodSignatureToString(java.lang.String signature, java.lang.String name, java.lang.String access, boolean chopit)
           
static java.lang.String methodSignatureToString(java.lang.String signature, java.lang.String name, java.lang.String access, boolean chopit, LocalVariableTable vars)
          A return­type signature represents the return value from a method.
static java.lang.String methodTypeToSignature(java.lang.String ret, java.lang.String[] argv)
          Converts string containing the method return and argument types to a byte code method signature.
static java.lang.String printArray(java.lang.Object[] obj)
           
static java.lang.String printArray(java.lang.Object[] obj, boolean braces)
           
static void printArray(java.io.PrintStream out, java.lang.Object[] obj)
           
static void printArray(java.io.PrintWriter out, java.lang.Object[] obj)
           
static java.lang.String replace(java.lang.String str, java.lang.String old, java.lang.String new_)
          Replace all occurences of old in str with new.
static short searchOpcode(java.lang.String name)
          Map opcode names to opcode numbers.
static int setBit(int flag, int i)
           
static java.lang.String signatureToString(java.lang.String signature)
          Converts signature to string with all class names compacted.
static java.lang.String signatureToString(java.lang.String signature, boolean chopit)
          The field signature represents the value of an argument to a function or the value of a variable.
static java.lang.String toHexString(byte[] bytes)
          Convert bytes into hexidecimal string
static byte typeOfMethodSignature(java.lang.String signature)
          Return type of method signature as a byte value as defined in Constants
static byte typeOfSignature(java.lang.String signature)
          Return type of signature as a byte value as defined in Constants
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

Utility

public Utility()
Method Detail

accessToString

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

accessToString

public static final java.lang.String accessToString(int access_flags,
                                                    boolean for_class)
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:
access_flags - Access flags
for_class - access flags are for class qualifiers ?
Returns:
String representation of flags

classOrInterface

public static final java.lang.String classOrInterface(int access_flags)
Returns:
"class" or "interface", depending on the ACC_INTERFACE flag

codeToString

public static final java.lang.String codeToString(byte[] code,
                                                  ConstantPool constant_pool,
                                                  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
constant_pool - 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, e.g. print constant pool index
Returns:
String representation of byte codes

codeToString

public static final java.lang.String codeToString(byte[] code,
                                                  ConstantPool constant_pool,
                                                  int index,
                                                  int length)

codeToString

public static final java.lang.String codeToString(ByteSequence bytes,
                                                  ConstantPool constant_pool,
                                                  boolean verbose)
                                           throws java.io.IOException
Disassemble a stream of byte codes and return the string representation.
Parameters:
bytes - stream of bytes
constant_pool - Array of constants
verbose - be verbose, e.g. print constant pool index
Returns:
String representation of byte code

codeToString

public static final java.lang.String codeToString(ByteSequence bytes,
                                                  ConstantPool constant_pool)
                                           throws java.io.IOException

compactClassName

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

compactClassName

public static final java.lang.String compactClassName(java.lang.String str,
                                                      java.lang.String prefix,
                                                      boolean chopit)
Shorten long class name str, i.e., 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

compactClassName

public static final java.lang.String compactClassName(java.lang.String str,
                                                      boolean chopit)
Shorten long class names, java/lang/String becomes java.lang.String, e.g.. 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

setBit

public static final int setBit(int flag,
                               int i)
Returns:
`flag' with bit `i' set to 1

clearBit

public static final int clearBit(int flag,
                                 int i)
Returns:
`flag' with bit `i' set to 0

isSet

public static final boolean isSet(int flag,
                                  int i)
Returns:
true, if bit `i' in `flag' is set

methodTypeToSignature

public static final java.lang.String methodTypeToSignature(java.lang.String ret,
                                                           java.lang.String[] argv)
                                                    throws java.lang.ClassFormatError
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

methodSignatureArgumentTypes

public static final java.lang.String[] methodSignatureArgumentTypes(java.lang.String signature)
                                                             throws java.lang.ClassFormatError
Parameters:
signature - Method signature
Returns:
Array of argument types

methodSignatureArgumentTypes

public static final java.lang.String[] methodSignatureArgumentTypes(java.lang.String signature,
                                                                    boolean chopit)
                                                             throws java.lang.ClassFormatError
Parameters:
signature - Method signature
chopit - Shorten class names ?
Returns:
Array of argument types

methodSignatureReturnType

public static final java.lang.String methodSignatureReturnType(java.lang.String signature)
                                                        throws java.lang.ClassFormatError
Parameters:
signature - Method signature
Returns:
return type of method

methodSignatureReturnType

public static final java.lang.String methodSignatureReturnType(java.lang.String signature,
                                                               boolean chopit)
                                                        throws java.lang.ClassFormatError
Parameters:
signature - Method signature
chopit - Shorten class names ?
Returns:
return type of method

methodSignatureToString

public static final java.lang.String methodSignatureToString(java.lang.String signature,
                                                             java.lang.String name,
                                                             java.lang.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 final java.lang.String methodSignatureToString(java.lang.String signature,
                                                             java.lang.String name,
                                                             java.lang.String access,
                                                             boolean chopit)

methodSignatureToString

public static final java.lang.String methodSignatureToString(java.lang.String signature,
                                                             java.lang.String name,
                                                             java.lang.String access,
                                                             boolean chopit,
                                                             LocalVariableTable vars)
                                                      throws java.lang.ClassFormatError
A return­type signature represents the return value from a method. It is a series of bytes in the following grammar: ::= | V The character V indicates that the method returns no value. Otherwise, the signature indicates the type of the return value. An argument signature represents an argument passed to a method: ::= A method signature represents the arguments that the method expects, and the value that it returns. ::= () ::= * This method converts such a string into a Java type declaration like `void main(String[])' and throws a `ClassFormatError' when the parsed type is invalid.
Parameters:
signature - Method signature
name - Method name
access - Method access rights
Returns:
Java type declaration

replace

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

signatureToString

public static final java.lang.String signatureToString(java.lang.String signature)
Converts signature to string with all class names compacted.
Parameters:
signature - to convert
Returns:
Human readable signature

signatureToString

public static final java.lang.String signatureToString(java.lang.String signature,
                                                       boolean chopit)
The field signature represents the value of an argument to a function or the value of a variable. It is a series of bytes generated by the following grammar: 
  ::= 
       ::= ||
        ::= B|C|D|F|I|J|S|Z
      ::= L;
       ::= [

 The meaning of the base types is as follows:
 B byte signed byte
 C char character
 D double double precision IEEE float
 F float single precision IEEE float
 I int integer
 J long long integer
 L; ... an object of the given class
 S short signed short
 Z boolean true or false
 [ ... array
This method converts this string into a Java type declaration such as `String[]' and throws a `ClassFormatError' when the parsed type is invalid.
Parameters:
signature - Class signature
chopit - Flag that determines whether chopping is executed or not
Returns:
Java type declaration
Throws:
java.lang.ClassFormatError -  

getSignature

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

typeOfMethodSignature

public static final byte typeOfMethodSignature(java.lang.String signature)
                                        throws java.lang.ClassFormatError
Return type of method signature as a byte value as defined in Constants
Parameters:
signature - in format described above
Returns:
type of method signature
See Also:
Constants

typeOfSignature

public static final byte typeOfSignature(java.lang.String signature)
                                  throws java.lang.ClassFormatError
Return type of signature as a byte value as defined in Constants
Parameters:
signature - in format described above
Returns:
type of signature
See Also:
Constants

searchOpcode

public static short searchOpcode(java.lang.String name)
Map opcode names to opcode numbers. E.g., return Constants.ALOAD for "aload"

toHexString

public static final java.lang.String toHexString(byte[] bytes)
Convert bytes into hexidecimal string
Returns:
bytes as hexidecimal string, e.g. 00 FA 12 ...

format

public static final java.lang.String format(int i,
                                            int length,
                                            boolean left_justify,
                                            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
left_justify - format left or right
fill - fill character
Returns:
formatted int

fillup

public static final java.lang.String fillup(java.lang.String str,
                                            int length,
                                            boolean left_justify,
                                            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
left_justify - format left or right
fill - fill character
Returns:
formatted string

printArray

public static final void printArray(java.io.PrintStream out,
                                    java.lang.Object[] obj)

printArray

public static final void printArray(java.io.PrintWriter out,
                                    java.lang.Object[] obj)

printArray

public static final java.lang.String printArray(java.lang.Object[] obj)

printArray

public static final java.lang.String printArray(java.lang.Object[] obj,
                                                boolean braces)

isJavaIdentifierPart

public static boolean isJavaIdentifierPart(char ch)
Returns:
true, if character is one of (a, ... z, A, ... Z, 0, ... 9, _)

encode

public static java.lang.String encode(byte[] bytes,
                                      boolean compress)
                               throws java.io.IOException
Encode byte array it into Java identifier string, i.e., 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

decode

public static byte[] decode(java.lang.String s,
                            boolean uncompress)
                     throws java.io.IOException
Decode a string back to a byte array.
Parameters:
bytes - the byte array to convert
uncompress - use gzip to uncompress the stream of bytes
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