org.objectweb.asm
Class ClassReader
A Java class parser to make a
ClassVisitor
visit an
existing class. This class parses a byte array conforming to the Java class
file format and calls the appropriate visit methods of a given class visitor
for each field, method and bytecode instruction encountered.
byte[] | b - The class to be parsed.
|
void | accept(ClassVisitor classVisitor, boolean skipDebug) - Makes the given visitor visit the Java class of this
ClassReader .
|
void | accept(ClassVisitor classVisitor, Attribute[] attrs, boolean skipDebug) - Makes the given visitor visit the Java class of this
ClassReader .
|
int | getItem(int item) - Returns the start index of the constant pool item in
b , plus
one.
|
protected Attribute | readAttribute(Attribute[] attrs, String type, int off, int len, char[] buf, int codeOff, Label[] labels) - Reads an attribute in
b .
|
int | readByte(int index) - Reads a byte value in
b .
|
String | readClass(int index, char[] buf) - Reads a class constant pool item in
b .
|
Object | readConst(int item, char[] buf) - Reads a numeric or string constant pool item in
b .
|
int | readInt(int index) - Reads a signed int value in
b .
|
long | readLong(int index) - Reads a signed long value in
b .
|
short | readShort(int index) - Reads a signed short value in
b .
|
String | readUTF8(int index, char[] buf) - Reads an UTF8 string constant pool item in
b .
|
int | readUnsignedShort(int index) - Reads an unsigned short value in
b .
|
b
public final byte[] b
The class to be parsed.
The content of this array must not be
modified. This field is intended for Attribute
sub classes, and is
normally not needed by class generators or adapters.
ClassReader
public ClassReader(InputStream is)
throws IOException
is
- an input stream from which to read the class.
ClassReader
public ClassReader(String name)
throws IOException
name
- the fully qualified name of the class to be read.
ClassReader
public ClassReader(byte[] b)
b
- the bytecode of the class to be read.
ClassReader
public ClassReader(byte[] b,
int off,
int len)
b
- the bytecode of the class to be read.off
- the start offset of the class data.len
- the length of the class data.
accept
public void accept(ClassVisitor classVisitor,
boolean skipDebug)
Makes the given visitor visit the Java class of this
ClassReader
. This class is the one specified in the constructor (see
ClassReader
).
classVisitor
- the visitor that must visit this class.skipDebug
- true if the debug information of the class must
not be visited. In this case the visitLocalVariable
and visitLineNumber
methods will not be called.
accept
public void accept(ClassVisitor classVisitor,
Attribute[] attrs,
boolean skipDebug)
Makes the given visitor visit the Java class of this
ClassReader
. This class is the one specified in the constructor (see
ClassReader
).
classVisitor
- the visitor that must visit this class.attrs
- prototypes of the attributes that must be parsed during the
visit of the class. Any attribute whose type is not equal to the type
of one the prototypes will be ignored.skipDebug
- true if the debug information of the class must
not be visited. In this case the visitLocalVariable
and visitLineNumber
methods will not be called.
getItem
public int getItem(int item)
Returns the start index of the constant pool item in
b
, plus
one.
This method is intended for Attribute
sub classes, and is
normally not needed by class generators or adapters.
item
- the index a constant pool item.
- the start index of the constant pool item in
b
, plus
one.
readAttribute
protected Attribute readAttribute(Attribute[] attrs,
String type,
int off,
int len,
char[] buf,
int codeOff,
Label[] labels)
attrs
- prototypes of the attributes that must be parsed during the
visit of the class. Any attribute whose type is not equal to the type
of one the prototypes is ignored (i.e. an empty Attribute
instance is returned).type
- the type of the attribute.off
- index of the first byte of the attribute's content in b
. The 6 attribute header bytes, containing the type and the length
of the attribute, are not taken into account here (they have already
been read).len
- the length of the attribute's content.buf
- buffer to be used to call readUTF8
, readClass
or readConst
.codeOff
- index of the first byte of code's attribute content in
b
, or -1 if the attribute to be read is not a code
attribute. The 6 attribute header bytes, containing the type and the
length of the attribute, are not taken into account here.labels
- the labels of the method's code, or null if the
attribute to be read is not a code attribute.
- the attribute that has been read, or null to skip this
attribute.
readByte
public int readByte(int index)
Reads a byte value in
b
.
This method is intended
for Attribute
sub classes, and is normally not needed by class
generators or adapters.
index
- the start index of the value to be read in b
.
readClass
public String readClass(int index,
char[] buf)
Reads a class constant pool item in
b
.
This method is
intended for Attribute
sub classes, and is normally not needed by
class generators or adapters.
index
- the start index of an unsigned short value in b
,
whose value is the index of a class constant pool item.buf
- buffer to be used to read the item. This buffer must be
sufficiently large. It is not automatically resized.
- the String corresponding to the specified class item.
readConst
public Object readConst(int item,
char[] buf)
Reads a numeric or string constant pool item in
b
.
This
method is intended for Attribute
sub classes, and is normally not
needed by class generators or adapters.
item
- the index of a constant pool item.buf
- buffer to be used to read the item. This buffer must be
sufficiently large. It is not automatically resized.
readInt
public int readInt(int index)
Reads a signed int value in
b
.
This method is intended
for Attribute
sub classes, and is normally not needed by class
generators or adapters.
index
- the start index of the value to be read in b
.
readLong
public long readLong(int index)
Reads a signed long value in
b
.
This method is intended
for Attribute
sub classes, and is normally not needed by class
generators or adapters.
index
- the start index of the value to be read in b
.
readShort
public short readShort(int index)
Reads a signed short value in
b
.
This method is intended
for Attribute
sub classes, and is normally not needed by class
generators or adapters.
index
- the start index of the value to be read in b
.
readUTF8
public String readUTF8(int index,
char[] buf)
Reads an UTF8 string constant pool item in
b
.
This method is
intended for Attribute
sub classes, and is normally not needed by
class generators or adapters.
index
- the start index of an unsigned short value in b
,
whose value is the index of an UTF8 constant pool item.buf
- buffer to be used to read the item. This buffer must be
sufficiently large. It is not automatically resized.
- the String corresponding to the specified UTF8 item.
readUnsignedShort
public int readUnsignedShort(int index)
Reads an unsigned short value in
b
.
This method is intended
for Attribute
sub classes, and is normally not needed by class
generators or adapters.
index
- the start index of the value to be read in b
.