cf
Class ClassFile

java.lang.Object
  cf.ClassFile

Direct Known Subclasses:

Obfuscate, View

public class ClassFile
extends Object

An instance of class ClassFile is an in-core representation of a Java class file.

Version:

$Id: ClassFile.java,v 1.135 2003/11/23 06:58:30 rl Exp $

Author:

Zvi Har’El

See Also:

Class source code

Nested Class Summary

protected static class

ClassFile.ByteArray An instance of the inner class ByteArray is an immutable wrapper to a byte[] object.

Field Summary

(package private) short	access Class access modifiers.
(package private) Vector	attributes Attributes of this class.
(package private) Vector	cP Constant pool.
(package private) short	cPCode UTF8 constant for “Code”.
(package private) Hashtable	cPHash Constant pool hash table.
(package private) Vector	fields Fields declared by this class.
(package private) Vector	interfaces Superinterfaces of this class.
(package private) short	major Major version number of this class file.
(package private) Vector	methods Methods declared by this class.
(package private) short	minor Minor version number of this class file.
(package private) short	superClass The direct superclass of this class.
(package private) short	thisClass The class defined by this class file.

Constructor Summary

ClassFile()
Constructs an empty ClassFile object.

ClassFile(DataInputStream in)
Constructs a ClassFile object by reading an input stream.

Method Summary

void	addInterface(String name) Adds a name to the list of interfaces implemented by this class.
private short	cp(byte[] b) Inserts a constant to the pool.
(package private) short	cp(byte tag, double c) Inserts a DOUBLE constant.
(package private) short	cp(byte tag, float c) Inserts a FLOAT constant.
(package private) short	cp(byte tag, int c) Inserts an INTEGER constant.
(package private) short	cp(byte tag, long c) Inserts a LONG constant.
private short	cp(byte tag, short i) Inserts a constant.
private short	cp(byte tag, short i, short j) Inserts a constant.
(package private) short	cp(byte tag, short i, String name, String desc) Inserts a FIELDREF, METHODREF or INTERFACEMETHODREF constant.
(package private) short	cp(byte tag, String s) Inserts a UTF8, CLASS or STRING constant.
(package private) short	cp(byte tag, String name, String desc) Inserts a NAMEANDTYPE constant.
(package private) short	cp(byte tag, String s, String name, String desc) Inserts a FIELDREF, METHODREF or INTERFACEMETHODREF constant.
(package private) static String	desc(Class type) Returns a descriptor of a field.
(package private) static String	desc(Class[] param, Class type) Returns a descriptor of a method.
static InputStream	findClassInPath(String name) Finds a class file in the user class path.
(package private) short	findUTF8(String s) Finds a UTF8 constant in the pool.
byte[]	getBytes() Writes the ClassFile object on a byte array.
static ClassFile	getClassFile(String name) Gets a ClassFile object for a named class by reading a class file from the user class path.
(package private) Object	readAttribute(DataInputStream in) Reads an attribute table from the input stream.
(package private) void	renameClass(short i, String name) Renames a class.
void	setName(String name) Sets the name of this class.
void	setSuper(String name) Sets the name of the direct superclass of this class.
void	strip() Strips attributes.
(package private) static byte[]	toUTF8(String s) Computes the UTF-8 encoding of a string.
void	write(DataOutputStream out) Writes the ClassFile object on an output stream.
void	write(String s) Writes the ClassFile object on a file.
(package private) static void	writeAttribute(DataOutputStream out, byte[] b)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

cP

final Vector cP

Constant pool. Each entry is a ClassFile.ByteArray object.

cPHash

final Hashtable cPHash

Constant pool hash table. Maps byte arrays to pool indices.

cPCode

short cPCode

UTF8 constant for “Code”.

minor

short minor

Minor version number of this class file.

major

short major

Major version number of this class file.

access

short access

Class access modifiers.

thisClass

short thisClass

The class defined by this class file. An index to a CLASS constant.

superClass

short superClass

The direct superclass of this class. An index to a CLASS constant.

interfaces

final Vector interfaces

Superinterfaces of this class. Each entry is a Short object wrapping an index to a CLASS constant.

fields

final Vector fields

Fields declared by this class. Each entry is a MemberInfo object.

methods

final Vector methods

Methods declared by this class. Each entry is a MemberInfo object.

attributes

final Vector attributes

Attributes of this class. The only attribute possible at this level is “SourceFile”. Each entry is a byte array.

Constructor Detail

ClassFile

ClassFile()

Constructs an empty ClassFile object.

ClassFile

public ClassFile(DataInputStream in)
          throws IOException

Constructs a ClassFile object by reading an input stream.

Parameters:

in - the input stream

Throws:

ClassFormatError - if input cannot be interpreted as a class file

IOException - if input error occurs

Method Detail

getClassFile

public static ClassFile getClassFile(String name)
                              throws IOException,
                                     ClassNotFoundException

Gets a ClassFile object for a named class by reading a class file from the user class path.

Parameters:

name - the class name

Throws:

IOException - if input error occurs

ClassFormatError - if input cannot be interpreted as a class file

ClassNotFoundException - if class file is not found

findClassInPath

public static final InputStream findClassInPath(String name)
                                         throws ClassNotFoundException

Finds a class file in the user class path.

Parameters:

name - the class name

Returns:

an input stream

Throws:

ClassNotFoundException - if class file is not found

write

public final void write(DataOutputStream out)
                 throws IOException

Writes the ClassFile object on an output stream.

Parameters:

out - the output stream

Throws:

IOException - if output error occurs

write

public final void write(String s)
                 throws IOException

Writes the ClassFile object on a file.

Parameters:

s - a file name

Throws:

IOException - if output error occurs

getBytes

public final byte[] getBytes()
                      throws IOException

Writes the ClassFile object on a byte array.

Returns:

the byte array

Throws:

IOException - if output error occurs

strip

public final void strip()

Strips attributes.

cp

private final short cp(byte[] b)

Inserts a constant to the pool.

Parameters:

b - a byte array

Returns:

the index of the new constant

cp

private final short cp(byte tag,
                       short i)

Inserts a constant.

Parameters:

tag - a constant pool tag

i - an index to constant pool

Returns:

the index of the new constant

cp

private final short cp(byte tag,
                       short i,
                       short j)

Inserts a constant.

Parameters:

tag - a constant pool tag

i - an index to constant pool

j - an index to constant pool

Returns:

the index of the new constant

cp

final short cp(byte tag,
               String s)

Inserts a UTF8, CLASS or STRING constant. In the latter cases, an intermediate UTF8 constant is created.

Parameters:

tag - a constant pool tag

s - a String value

Returns:

the index of the new constant

See Also:

JVM Spec §4.4.7, §4.4.1, §4.4.3

cp

final short cp(byte tag,
               String name,
               String desc)

Inserts a NAMEANDTYPE constant. Two intermediate UTF8 constants are created.

Parameters:

tag - a constant pool tag

name - a member name

desc - a member descriptor

Returns:

the index of the new the constant

See Also:

JVM Spec §4.4.6

cp

final short cp(byte tag,
               String s,
               String name,
               String desc)

Inserts a FIELDREF, METHODREF or INTERFACEMETHODREF constant. Two intermediate CLASS and NAMEANDTYPE constants are created.

Parameters:

tag - a constant pool tag

s - a class name in internal form

name - a member name

desc - a member descriptor

Returns:

the index of the new constant

See Also:

JVM Spec §4.4.2

cp

final short cp(byte tag,
               short i,
               String name,
               String desc)

Inserts a FIELDREF, METHODREF or INTERFACEMETHODREF constant. An intermediate NAMEANDTYPE constant is created.

Parameters:

tag - a constant pool tag

i - an index to a CLASS constant

name - a member name

desc - a member descriptor

Returns:

the index of the new constant

See Also:

JVM Spec §4.4.2

cp

final short cp(byte tag,
               int c)

Inserts an INTEGER constant. Also called internally to insert a four-byte constant which contains a float value.

Parameters:

tag - a constant pool tag

c - an int value

Returns:

the index of the new constant

See Also:

JVM Spec §4.4.4

cp

final short cp(byte tag,
               float c)

Inserts a FLOAT constant.

Parameters:

tag - a constant pool tag

c - a float value

Returns:

the index of the new constant

See Also:

JVM Spec §4.4.4

cp

final short cp(byte tag,
               long c)

Inserts a LONG constant. Also called internally to insert an eight-byte constant which contains a double value. The next pool entry is marked invalid.

Note:

In retrospect, making eight-byte constants take two constant pool entries was a poor choice.

Parameters:

tag - a constant pool tag

c - a long value

Returns:

the index of the new constant

See Also:

JVM Spec §4.4.5, footnote 2 therein

cp

final short cp(byte tag,
               double c)

Inserts a DOUBLE constant.

Parameters:

tag - a constant pool tag

c - a double value

Returns:

the index of the new constant

See Also:

JVM Spec §4.4.5

toUTF8

static final byte[] toUTF8(String s)

Computes the UTF-8 encoding of a string.

Parameters:

s - a String value

Returns:

the equivalent byte array

See Also:

DataOutput.writeUTF(java.lang.String), RFC2279

findUTF8

final short findUTF8(String s)

Finds a UTF8 constant in the pool.

Parameters:

s - a String value

Returns:

the index of the constant, or zero if not found

setName

public final void setName(String name)

Sets the name of this class.

Parameters:

name - a class name.

setSuper

public final void setSuper(String name)

Sets the name of the direct superclass of this class.

Parameters:

name - a class name.

renameClass

final void renameClass(short i,
                       String name)

Renames a class. The CLASS constant is removed from the pool and a new CLASS constant is inserted in the same place.

Parameters:

i - an index to a CLASS constant

name - a class name in internal form.

See Also:

JVM Spec §4.2

addInterface

public final void addInterface(String name)

Adds a name to the list of interfaces implemented by this class.

Parameters:

name - a class name.

readAttribute

final Object readAttribute(DataInputStream in)
                    throws IOException

Reads an attribute table from the input stream. The attribute is stored in a byte array. Its length is not stored. “Code” attributes are transformed into CodeAttribute objects.

Parameters:

in - the input stream

Returns:

the attribute

Throws:

IOException - if an input error occurs.

See Also:

JVM Spec §4.7

writeAttribute

static final void writeAttribute(DataOutputStream out,
                                 byte[] b)
                          throws IOException

Throws:

IOException

desc

static final String desc(Class type)

Returns a descriptor of a field.

Parameters:

type - the field type

Returns:

the descriptor

See Also:

JVM Spec §4.3.2

desc

static final String desc(Class[] param,
                         Class type)

Returns a descriptor of a method. If the method has no parameters, either null or an empty Class array are acceptable as the parameter types.

Parameters:

param - the parameter types

type - the return type

Returns:

the descriptor

See Also:

JVM Spec §4.3.3