org.apache.bcel.classfile

Class 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 1.5 2002/04/24 11:01:30 mdahm Exp $
Author:
M. Dahm

Method Summary

static String
accessToString(int access_flags)
Convert bit field of flags into string such as `static final'.
static String
accessToString(int access_flags, boolean for_class)
Convert bit field of flags into string such as `static final'.
static String
classOrInterface(int access_flags)
static int
clearBit(int flag, int i)
static String
codeToString(byte[] code, ConstantPool constant_pool, int index, int length)
static 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 String
codeToString(ByteSequence bytes, ConstantPool constant_pool)
static String
codeToString(ByteSequence bytes, ConstantPool constant_pool, boolean verbose)
Disassemble a stream of byte codes and return the string representation.
static String
compactClassName(String str)
Shorten long class names, java/lang/String becomes String.
static String
compactClassName(String str, 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 String
compactClassName(String str, boolean chopit)
Shorten long class names, java/lang/String becomes java.lang.String, e.g..
static String
convertString(String label)
Escape all occurences of newline chars '\n', quotes \", etc.
static byte[]
decode(String s, boolean uncompress)
Decode a string back to a byte array.
static 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 String
fillup(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 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 String
getSignature(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 String[]
methodSignatureArgumentTypes(String signature)
static String[]
methodSignatureArgumentTypes(String signature, boolean chopit)
static String
methodSignatureReturnType(String signature)
static String
methodSignatureReturnType(String signature, boolean chopit)
static String
methodSignatureToString(String signature, String name, String access)
Converts method signature to string with all class names compacted.
static String
methodSignatureToString(String signature, String name, String access, boolean chopit)
static String
methodSignatureToString(String signature, String name, String access, boolean chopit, LocalVariableTable vars)
A return?type signature represents the return value from a method.
static String
methodTypeToSignature(String ret, String[] argv)
Converts string containing the method return and argument types to a byte code method signature.
static String
printArray(Object[] obj)
static String
printArray(Object[] obj, boolean braces)
static String
printArray(Object[] obj, boolean braces, boolean quote)
static void
printArray(PrintStream out, Object[] obj)
static void
printArray(PrintWriter out, Object[] obj)
static String
replace(String str, String old, String new_)
Replace all occurences of old in str with new.
static short
searchOpcode(String name)
Map opcode names to opcode numbers.
static int
setBit(int flag, int i)
static String
signatureToString(String signature)
Converts signature to string with all class names compacted.
static String
signatureToString(String signature, boolean chopit)
The field signature represents the value of an argument to a function or the value of a variable.
static String
toHexString(byte[] bytes)
Convert bytes into hexidecimal string
static byte
typeOfMethodSignature(String signature)
Return type of method signature as a byte value as defined in Constants
static byte
typeOfSignature(String signature)
Return type of signature as a byte value as defined in Constants

Method Details

accessToString

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

clearBit

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

codeToString

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

codeToString

public static final 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 String codeToString(ByteSequence bytes,
                                        ConstantPool constant_pool)
            throws IOException

codeToString

public static final String codeToString(ByteSequence bytes,
                                        ConstantPool constant_pool,
                                        boolean verbose)
            throws 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

compactClassName

public static final 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 final String compactClassName(String str,
                                            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 String compactClassName(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

convertString

public static final String convertString(String label)
Escape all occurences of newline chars '\n', quotes \", etc.

decode

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

encode

public static String encode(byte[] bytes,
                            boolean compress)
            throws 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

Parameters:
bytes - the byte array to convert
compress - use gzip to minimize string

fillup

public static final String fillup(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

format

public static final 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

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, e.g. "C" or "[Ljava/lang/String;" respectively.
Parameters:
type - Java type
Returns:
byte code signature

isJavaIdentifierPart

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

isSet

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

methodSignatureArgumentTypes

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

methodSignatureArgumentTypes

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

methodSignatureReturnType

public static final String methodSignatureReturnType(String signature)
            throws ClassFormatException
Parameters:
signature - Method signature
Returns:
return type of method

methodSignatureReturnType

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

methodSignatureToString

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

methodSignatureToString

public static final String methodSignatureToString(String signature,
                                                   String name,
                                                   String access,
                                                   boolean chopit,
                                                   LocalVariableTable vars)
            throws ClassFormatException
A return?type 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 `ClassFormatException' when the parsed type is invalid.
Parameters:
signature - Method signature
name - Method name
access - Method access rights
Returns:
Java type declaration

methodTypeToSignature

public static final 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

printArray

public static final String printArray(Object[] obj)

printArray

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

printArray

public static final String printArray(Object[] obj,
                                      boolean braces,
                                      boolean quote)

printArray

public static final void printArray(PrintStream out,
                                    Object[] obj)

printArray

public static final void printArray(PrintWriter out,
                                    Object[] obj)

replace

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

searchOpcode

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

setBit

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

signatureToString

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

signatureToString

public static final String signatureToString(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 `ClassFormatException' when the parsed type is invalid.
Parameters:
signature - Class signature
chopit - Flag that determines whether chopping is executed or not
Returns:
Java type declaration

toHexString

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

typeOfMethodSignature

public static final 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
See Also:
Constants

typeOfSignature

public static final 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
See Also:
Constants