org.apache.bcel.classfile

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.

Version:

$Id: Utility.java 386056 2006-03-15 11:31:56Z tcurdt $

Author:

M. Dahm

Constructor Summary

Constructors

Constructor and Description
Utility()

Method Summary

Methods

Modifier and Type	Method and Description
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, boolean chopit) Shorten long class names, java/lang/String becomes java.lang.String, e.g..
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	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 return­type 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

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 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

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(byte[] code,
                  ConstantPool constant_pool,
                  int index,
                  int length)

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

Throws:

IOException

codeToString

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

Throws:

IOException

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

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 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

methodSignatureArgumentTypes

public static final String[] methodSignatureArgumentTypes(String signature)
                                                   throws ClassFormatException

Parameters:

signature - Method signature

Returns:

Array of argument types

Throws:

ClassFormatException

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

Throws:

ClassFormatException

methodSignatureReturnType

public static final String methodSignatureReturnType(String signature)
                                              throws ClassFormatException

Parameters:

signature - Method signature

Returns:

return type of method

Throws:

ClassFormatException

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

Throws:

ClassFormatException

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 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 `ClassFormatException' when the parsed type is invalid.

Parameters:

signature - Method signature

name - Method name

access - Method access rights

Returns:

Java type declaration

Throws:

ClassFormatException

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

new_ - Replacement string

Returns:

new String object

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

Throws:

ClassFormatException

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

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

Throws:

ClassFormatException

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

Throws:

ClassFormatException

See Also:

Constants

searchOpcode

public static short searchOpcode(String name)

Map opcode names to opcode numbers. E.g., return Constants.ALOAD for "aload"

toHexString

public static final String toHexString(byte[] bytes)

Convert bytes into hexidecimal string

Returns:

bytes as hexidecimal string, e.g. 00 FA 12 ...

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

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

printArray

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

printArray

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

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)

isJavaIdentifierPart

public static boolean isJavaIdentifierPart(char ch)

Returns:

true, if character is one of (a, ... z, A, ... Z, 0, ... 9, _)

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

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

Parameters:

bytes - the byte array to convert

compress - use gzip to minimize string

Throws:

IOException

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

Throws:

IOException

convertString

public static final String convertString(String label)

Escape all occurences of newline chars '\n', quotes \", etc.