public class ClassReader extends Object
ClassVisitor
visit a ClassFile structure, as defined in the Java
Virtual Machine Specification (JVMS). This class parses the ClassFile content and calls the
appropriate visit methods of a given ClassVisitor
for each field, method and bytecode
instruction encountered.Modifier and Type | Field and Description |
---|---|
byte[] |
b
Deprecated.
Use
readByte(int) and the other read methods instead. This field will
eventually be deleted. |
static int |
EXPAND_FRAMES
A flag to expand the stack map frames.
|
int |
header
The offset in bytes of the ClassFile's access_flags field.
|
static int |
SKIP_CODE
A flag to skip the Code attributes.
|
static int |
SKIP_DEBUG
A flag to skip the SourceFile, SourceDebugExtension, LocalVariableTable,
LocalVariableTypeTable, LineNumberTable and MethodParameters attributes.
|
static int |
SKIP_FRAMES
A flag to skip the StackMap and StackMapTable attributes.
|
Constructor and Description |
---|
ClassReader(byte[] classFile)
Constructs a new
ClassReader object. |
ClassReader(byte[] classFileBuffer,
int classFileOffset,
int classFileLength)
Constructs a new
ClassReader object. |
ClassReader(InputStream inputStream)
Constructs a new
ClassReader object. |
ClassReader(String className)
Constructs a new
ClassReader object. |
Modifier and Type | Method and Description |
---|---|
void |
accept(ClassVisitor classVisitor,
Attribute[] attributePrototypes,
int parsingOptions)
Makes the given visitor visit the JVMS ClassFile structure passed to the constructor of this
ClassReader . |
void |
accept(ClassVisitor classVisitor,
int parsingOptions)
Makes the given visitor visit the JVMS ClassFile structure passed to the constructor of this
ClassReader . |
int |
getAccess()
Returns the class's access flags (see
Opcodes ). |
String |
getClassName()
Returns the internal name of the class (see
Type.getInternalName() ). |
String[] |
getInterfaces()
Returns the internal names of the implemented interfaces (see
Type.getInternalName() ). |
int |
getItem(int constantPoolEntryIndex)
Returns the start offset in this
ClassReader of a JVMS 'cp_info' structure (i.e. |
int |
getItemCount()
Returns the number of entries in the class's constant pool table.
|
int |
getMaxStringLength()
Returns a conservative estimate of the maximum length of the strings contained in the class's
constant pool table.
|
String |
getSuperName()
Returns the internal name of the super class (see
Type.getInternalName() ). |
int |
readByte(int offset)
Reads a byte value in this
ClassReader . |
protected void |
readBytecodeInstructionOffset(int bytecodeOffset)
Handles the bytecode offset of the next instruction to be visited in
accept(ClassVisitor,int) . |
String |
readClass(int offset,
char[] charBuffer)
Reads a CONSTANT_Class constant pool entry in this
ClassReader . |
Object |
readConst(int constantPoolEntryIndex,
char[] charBuffer)
Reads a numeric or string constant pool entry in this
ClassReader . |
int |
readInt(int offset)
Reads a signed int value in this
ClassReader . |
protected Label |
readLabel(int bytecodeOffset,
Label[] labels)
Returns the label corresponding to the given bytecode offset.
|
long |
readLong(int offset)
Reads a signed long value in this
ClassReader . |
String |
readModule(int offset,
char[] charBuffer)
Reads a CONSTANT_Module constant pool entry in this
ClassReader . |
String |
readPackage(int offset,
char[] charBuffer)
Reads a CONSTANT_Package constant pool entry in this
ClassReader . |
short |
readShort(int offset)
Reads a signed short value in this
ClassReader . |
int |
readUnsignedShort(int offset)
Reads an unsigned short value in this
ClassReader . |
String |
readUTF8(int offset,
char[] charBuffer)
Reads a CONSTANT_Utf8 constant pool entry in this
ClassReader . |
public static final int SKIP_CODE
public static final int SKIP_DEBUG
ClassVisitor.visitSource(java.lang.String, java.lang.String)
, MethodVisitor.visitLocalVariable(java.lang.String, java.lang.String, java.lang.String, jersey.repackaged.org.objectweb.asm.Label, jersey.repackaged.org.objectweb.asm.Label, int)
, MethodVisitor.visitLineNumber(int, jersey.repackaged.org.objectweb.asm.Label)
and MethodVisitor.visitParameter(java.lang.String, int)
are not called).public static final int SKIP_FRAMES
MethodVisitor.visitFrame(int, int, java.lang.Object[], int, java.lang.Object[])
is not 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.public static final int EXPAND_FRAMES
@Deprecated public final byte[] b
readByte(int)
and the other read methods instead. This field will
eventually be deleted.public final int header
public ClassReader(byte[] classFile)
ClassReader
object.classFile
- the JVMS ClassFile structure to be read.public ClassReader(byte[] classFileBuffer, int classFileOffset, int classFileLength)
ClassReader
object.classFileBuffer
- a byte array containing the JVMS ClassFile structure to be read.classFileOffset
- the offset in byteBuffer of the first byte of the ClassFile to be read.classFileLength
- the length in bytes of the ClassFile to be read.public ClassReader(InputStream inputStream) throws IOException
ClassReader
object.inputStream
- an input stream of the JVMS ClassFile structure to be read. This input
stream must contain nothing more than the ClassFile structure itself. It is read from its
current position to its end.IOException
- if a problem occurs during reading.public ClassReader(String className) throws IOException
ClassReader
object.className
- the fully qualified name of the class to be read. The ClassFile structure is
retrieved with the current class loader's ClassLoader.getSystemResourceAsStream(java.lang.String)
.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 String getClassName()
Type.getInternalName()
).ClassVisitor.visit(int, int, String, String, String, String[])
public String getSuperName()
Type.getInternalName()
). For
interfaces, the super class is Object
.Object
class.ClassVisitor.visit(int, int, String, String, String, String[])
public String[] getInterfaces()
Type.getInternalName()
).ClassVisitor.visit(int, int, String, String, String, String[])
public void accept(ClassVisitor classVisitor, int parsingOptions)
ClassReader
.classVisitor
- the visitor that must visit this class.parsingOptions
- the options to use to parse this class. One or more of SKIP_CODE
, SKIP_DEBUG
, SKIP_FRAMES
or EXPAND_FRAMES
.public void accept(ClassVisitor classVisitor, Attribute[] attributePrototypes, int parsingOptions)
ClassReader
.classVisitor
- the visitor that must visit this class.attributePrototypes
- 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.parsingOptions
- the options to use to parse this class. One or more of SKIP_CODE
, SKIP_DEBUG
, SKIP_FRAMES
or EXPAND_FRAMES
.protected void readBytecodeInstructionOffset(int bytecodeOffset)
accept(ClassVisitor,int)
. This method is called just before the instruction and before its
associated label and stack map frame, if any. The default implementation of this method does
nothing. Subclasses can override this method to store the argument in a mutable field, for
instance, so that MethodVisitor
instances can get the bytecode offset of each visited
instruction (if so, the usual concurrency issues related to mutable data should be addressed).bytecodeOffset
- the bytecode offset of the next instruction to be visited.protected Label readLabel(int bytecodeOffset, Label[] labels)
bytecodeOffset
- a bytecode offset in a method.labels
- the already created labels, indexed by their offset. If a label already exists
for bytecodeOffset this method must not create a new one. Otherwise it must store the new
label in this array.public int getItemCount()
public int getItem(int constantPoolEntryIndex)
ClassReader
of a JVMS 'cp_info' structure (i.e. a
constant pool entry), plus one. This method is intended for Attribute
sub classes,
and is normally not needed by class generators or adapters.constantPoolEntryIndex
- the index a constant pool entry in the class's constant pool
table.ClassReader
of the corresponding JVMS 'cp_info'
structure, plus one.public int getMaxStringLength()
public int readByte(int offset)
ClassReader
. This method is intended for Attribute
sub classes, and is normally not needed by class generators or adapters.offset
- the start offset of the value to be read in this ClassReader
.public int readUnsignedShort(int offset)
ClassReader
. This method is intended for
Attribute
sub classes, and is normally not needed by class generators or adapters.offset
- the start index of the value to be read in this ClassReader
.public short readShort(int offset)
ClassReader
. This method is intended for Attribute
sub classes, and is normally not needed by class generators or adapters.offset
- the start offset of the value to be read in this ClassReader
.public int readInt(int offset)
ClassReader
. This method is intended for Attribute
sub classes, and is normally not needed by class generators or adapters.offset
- the start offset of the value to be read in this ClassReader
.public long readLong(int offset)
ClassReader
. This method is intended for Attribute
sub classes, and is normally not needed by class generators or adapters.offset
- the start offset of the value to be read in this ClassReader
.public String readUTF8(int offset, char[] charBuffer)
ClassReader
. This method is
intended for Attribute
sub classes, and is normally not needed by class generators or
adapters.offset
- the start offset of an unsigned short value in this ClassReader
, whose
value is the index of a CONSTANT_Utf8 entry in the class's constant pool table.charBuffer
- the buffer to be used to read the string. This buffer must be sufficiently
large. It is not automatically resized.public String readClass(int offset, char[] charBuffer)
ClassReader
. This method is
intended for Attribute
sub classes, and is normally not needed by class generators or
adapters.offset
- the start offset of an unsigned short value in this ClassReader
, whose
value is the index of a CONSTANT_Class entry in class's constant pool table.charBuffer
- the buffer to be used to read the item. This buffer must be sufficiently
large. It is not automatically resized.public String readModule(int offset, char[] charBuffer)
ClassReader
. This method is
intended for Attribute
sub classes, and is normally not needed by class generators or
adapters.offset
- the start offset of an unsigned short value in this ClassReader
, whose
value is the index of a CONSTANT_Module entry in class's constant pool table.charBuffer
- the buffer to be used to read the item. This buffer must be sufficiently
large. It is not automatically resized.public String readPackage(int offset, char[] charBuffer)
ClassReader
. This method is
intended for Attribute
sub classes, and is normally not needed by class generators or
adapters.offset
- the start offset of an unsigned short value in this ClassReader
, whose
value is the index of a CONSTANT_Package entry in class's constant pool table.charBuffer
- the buffer to be used to read the item. This buffer must be sufficiently
large. It is not automatically resized.public Object readConst(int constantPoolEntryIndex, char[] charBuffer)
ClassReader
. This method is
intended for Attribute
sub classes, and is normally not needed by class generators or
adapters.constantPoolEntryIndex
- the index of a CONSTANT_Integer, CONSTANT_Float, CONSTANT_Long,
CONSTANT_Double, CONSTANT_Class, CONSTANT_String, CONSTANT_MethodType,
CONSTANT_MethodHandle or CONSTANT_Dynamic entry in the class's constant pool.charBuffer
- the buffer to be used to read strings. This buffer must be sufficiently
large. It is not automatically resized.Integer
, Float
, Long
, Double
, String
,
Type
, Handle
or ConstantDynamic
corresponding to the specified
constant pool entry.Copyright © 2007-2023, Oracle and/or its affiliates. All Rights Reserved. Use is subject to license terms.