public class ClassReader
extends java.lang.Object
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.Modifier and Type | Field and Description |
---|---|
byte[] |
b
The class to be parsed.
|
static int |
EXPAND_FRAMES
Flag to expand the stack map frames.
|
int |
header
Start index of the class header information (access, name...) in
b . |
static int |
SKIP_CODE
Flag to skip method code.
|
static int |
SKIP_DEBUG
Flag to skip the debug information in the class.
|
static int |
SKIP_FRAMES
Flag to skip the stack map frames in the class.
|
Constructor and Description |
---|
ClassReader(byte[] b)
Constructs a new
ClassReader object. |
ClassReader(byte[] b,
int off,
int len)
Constructs a new
ClassReader object. |
ClassReader(java.io.InputStream is)
Constructs a new
ClassReader object. |
ClassReader(java.lang.String name)
Constructs a new
ClassReader object. |
Modifier and Type | Method and Description |
---|---|
void |
accept(ClassVisitor classVisitor,
Attribute[] attrs,
int flags)
Makes the given visitor visit the Java class of this
ClassReader . |
void |
accept(ClassVisitor classVisitor,
int flags)
Makes the given visitor visit the Java class of this
ClassReader
. |
int |
getAccess()
Returns the class's access flags (see
Opcodes ). |
java.lang.String |
getClassName()
Returns the internal name of the class (see
getInternalName ). |
java.lang.String[] |
getInterfaces()
Returns the internal names of the class's interfaces (see
getInternalName ). |
int |
getItem(int item)
Returns the start index of the constant pool item in
b , plus
one. |
int |
getItemCount()
Returns the number of constant pool items in
b . |
int |
getMaxStringLength()
Returns the maximum length of the strings contained in the constant pool
of the class.
|
java.lang.String |
getSuperName()
Returns the internal of name of the super class (see
getInternalName ). |
int |
readByte(int index)
Reads a byte value in
b . |
java.lang.String |
readClass(int index,
char[] buf)
Reads a class constant pool item in
b . |
java.lang.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 . |
protected Label |
readLabel(int offset,
Label[] labels)
Returns the label corresponding to the given offset.
|
long |
readLong(int index)
Reads a signed long value in
b . |
short |
readShort(int index)
Reads a signed short value in
b . |
int |
readUnsignedShort(int index)
Reads an unsigned short value in
b . |
java.lang.String |
readUTF8(int index,
char[] buf)
Reads an UTF8 string constant pool item in
b . |
public static final int SKIP_CODE
CODE
attribute won't be visited. This can be used, for example, to retrieve
annotations for methods and method parameters.public static final int SKIP_DEBUG
visitLocalVariable
and
visitLineNumber
methods will not be
called.public static final int SKIP_FRAMES
visitFrame
method will not be called.
This flag is useful when the ClassWriter.COMPUTE_FRAMES
option is
used: it avoids visiting frames that will be ignored and recomputed from
scratch in the class writer.public static final int EXPAND_FRAMES
public final byte[] b
Attribute
sub classes, and
is normally not needed by class generators or adapters.public final int header
b
.public ClassReader(byte[] b)
ClassReader
object.b
- the bytecode of the class to be read.public ClassReader(byte[] b, int off, int len)
ClassReader
object.b
- the bytecode of the class to be read.off
- the start offset of the class data.len
- the length of the class data.public ClassReader(java.io.InputStream is) throws java.io.IOException
ClassReader
object.is
- an input stream from which to read the class.java.io.IOException
- if a problem occurs during reading.public ClassReader(java.lang.String name) throws java.io.IOException
ClassReader
object.name
- the binary qualified name of the class to be read.java.io.IOException
- if an exception occurs during reading.public int getAccess()
Opcodes
). This value may
not reflect Deprecated and Synthetic flags when bytecode is before 1.5
and those flags are represented by attributes.ClassVisitor.visit(int, int, String, String, String, String[])
public java.lang.String getClassName()
getInternalName
).ClassVisitor.visit(int, int, String, String, String, String[])
public java.lang.String getSuperName()
getInternalName
). For interfaces, the
super class is Object
.Object
class.ClassVisitor.visit(int, int, String, String, String, String[])
public java.lang.String[] getInterfaces()
getInternalName
).ClassVisitor.visit(int, int, String, String, String, String[])
public void accept(ClassVisitor classVisitor, int flags)
ClassReader
. This class is the one specified in the constructor (see
ClassReader
).classVisitor
- the visitor that must visit this class.flags
- option flags that can be used to modify the default behavior
of this class. See SKIP_DEBUG
, EXPAND_FRAMES
, SKIP_FRAMES
, SKIP_CODE
.public void accept(ClassVisitor classVisitor, Attribute[] attrs, int flags)
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 not be parsed: its byte
array value will be passed unchanged to the ClassWriter.
This may corrupt it if this value contains references to
the constant pool, or has syntactic or semantic links with a
class element that has been transformed by a class adapter
between the reader and the writer.flags
- option flags that can be used to modify the default behavior
of this class. See SKIP_DEBUG
, EXPAND_FRAMES
, SKIP_FRAMES
, SKIP_CODE
.protected Label readLabel(int offset, Label[] labels)
offset
- a bytecode offset in a method.labels
- the already created labels, indexed by their offset. If a
label already exists for offset this method must not create a
new one. Otherwise it must store the new label in this array.public int getItemCount()
b
.b
.public int getItem(int item)
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.b
, plus
one.public int getMaxStringLength()
public int readByte(int index)
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
.public int readUnsignedShort(int index)
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
.public short readShort(int index)
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
.public int readInt(int index)
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
.public long readLong(int index)
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
.public java.lang.String readUTF8(int index, char[] buf)
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.public java.lang.String readClass(int index, char[] buf)
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.public java.lang.Object readConst(int item, char[] buf)