| java.lang.Object
 org.objectweb.asm.ClassWriter
| ClassWriter | | public class ClassWriter implements ClassVisitor(Code) | | A
ClassVisitor that generates classes in bytecode form. More
precisely this visitor generates a byte array conforming to the Java class
file format. It can be used alone, to generate a Java class "from scratch",
or with one or more
ClassReader ClassReader and adapter class visitor
to generate a modified class from one or more existing Java classes.
author:
Eric Bruneton |
| Field Summary | |
| final static int | CLASS
The type of CONSTANT_Class constant pool items. | | final public static int | COMPUTE_FRAMES
Flag to automatically compute the stack map frames of methods from
scratch. | | final public static int | COMPUTE_MAXS
Flag to automatically compute the maximum stack size and the maximum
number of local variables of methods. | | final static int | DOUBLE
The type of CONSTANT_Double constant pool items. | | final static int | FIELD
The type of CONSTANT_Fieldref constant pool items. | | final static int | FIELDORMETH_INSN
The type of field and method invocations instructions. | | final static int | FLOAT
The type of CONSTANT_Float constant pool items. | | final static int | IINC_INSN
The type of the IINC instruction. | | final static int | IMETH
The type of CONSTANT_InterfaceMethodref constant pool items. | | final static int | IMPLVAR_INSN
The type of instructions with an implicit local variable index argument. | | final static int | INT
The type of CONSTANT_Integer constant pool items. | | final static int | ITFMETH_INSN
The type of the INVOKEINTERFACE instruction. | | final static int | LABELW_INSN
The type of instructions with a 4 bytes bytecode offset label. | | final static int | LABEL_INSN
The type of instructions with a 2 bytes bytecode offset label. | | final static int | LDCW_INSN
The type of the LDC_W and LDC2_W instructions. | | final static int | LDC_INSN
The type of the LDC instruction. | | final static int | LONG
The type of CONSTANT_Long constant pool items. | | final static int | LOOK_INSN
The type of the LOOKUPSWITCH instruction. | | final static int | MANA_INSN
The type of the MULTIANEWARRAY instruction. | | final static int | METH
The type of CONSTANT_Methodref constant pool items. | | final static int | NAME_TYPE
The type of CONSTANT_NameAndType constant pool items. | | final static int | NOARG_INSN
The type of instructions without any argument. | | final static int | SBYTE_INSN
The type of instructions with an signed byte argument. | | final static int | SHORT_INSN
The type of instructions with an signed short argument. | | final static int | STR
The type of CONSTANT_String constant pool items. | | final static int | TABL_INSN
The type of the TABLESWITCH instruction. | | static byte[] | TYPE
The instruction types of all JVM opcodes. | | final static int | TYPE_INSN
The type of instructions with a type descriptor argument. | | final static int | TYPE_MERGED
Merged type Item stored in the ClassWriter
ClassWriter.typeTable ,
instead of the constant pool, in order to avoid clashes with normal
constant pool items in the ClassWriter constant pool's hash table. | | final static int | TYPE_NORMAL
Normal type Item stored in the ClassWriter
ClassWriter.typeTable ,
instead of the constant pool, in order to avoid clashes with normal
constant pool items in the ClassWriter constant pool's hash table. | | final static int | TYPE_UNINIT
Uninitialized type Item stored in the ClassWriter
ClassWriter.typeTable , instead of the constant pool, in order to
avoid clashes with normal constant pool items in the ClassWriter constant
pool's hash table. | | final static int | UTF8
The type of CONSTANT_Utf8 constant pool items. | | final static int | VAR_INSN
The type of instructions with a local variable index argument. | | final static int | WIDE_INSN
The type of the WIDE instruction. | | ClassReader | cr
The class reader from which this class writer was constructed, if any. | | FieldWriter | firstField
The fields of this class. | | MethodWriter | firstMethod
The methods of this class. | | int | index
Index of the next item to be added in the constant pool. | | boolean | invalidFrames
true if the stack map tables of this class are invalid. | | Item[] | items
The constant pool's hash table data. | | Item | key
A reusable key used to look for items in the
ClassWriter.items hash table. | | Item | key2
A reusable key used to look for items in the
ClassWriter.items hash table. | | Item | key3
A reusable key used to look for items in the
ClassWriter.items hash table. | | FieldWriter | lastField
The fields of this class. | | MethodWriter | lastMethod
The methods of this class. | | ByteVector | pool
The constant pool of this class. | | String | thisName
The internal name of this class. | | int | threshold
The threshold of the constant pool's hash table. | | Item[] | typeTable
A type table used to temporarily store internal names that will not
necessarily be stored in the constant pool. | | int | version
Minor and major version numbers of the class to be generated. |
| Constructor Summary | |
| public | ClassWriter(int flags)
Constructs a new
ClassWriter object.
Parameters:
flags - option flags that can be used to modify the default behaviorof this class. | | public | ClassWriter(ClassReader classReader, int flags)
Constructs a new
ClassWriter object and enables optimizations for
"mostly add" bytecode transformations. |
| Method Summary | |
| int | addType(String type)
Adds the given internal name to
ClassWriter.typeTable and returns its index.
Does nothing if the type table already contains this internal name.
Parameters:
type - the internal name to be added to the type table. | | int | addUninitializedType(String type, int offset)
Adds the given "uninitialized" type to
ClassWriter.typeTable and returns its
index. | | protected String | getCommonSuperClass(String type1, String type2)
Returns the common super type of the two given types. | | int | getMergedType(int type1, int type2)
Returns the index of the common super type of the two given types. | | public int | newClass(String value)
Adds a class reference to the constant pool of the class being build.
Does nothing if the constant pool already contains a similar item.
This method is intended for
Attribute sub classes, and is
normally not needed by class generators or adapters.
Parameters:
value - the internal name of the class. | | Item | newClassItem(String value)
Adds a class reference to the constant pool of the class being build.
Does nothing if the constant pool already contains a similar item.
This method is intended for
Attribute sub classes, and is
normally not needed by class generators or adapters.
Parameters:
value - the internal name of the class. | | public int | newConst(Object cst)
Adds a number or string constant to the constant pool of the class being
build. | | Item | newConstItem(Object cst)
Adds a number or string constant to the constant pool of the class being
build. | | Item | newDouble(double value)
Adds a double to the constant pool of the class being build. | | public int | newField(String owner, String name, String desc)
Adds a field reference to the constant pool of the class being build.
Does nothing if the constant pool already contains a similar item.
This method is intended for
Attribute sub classes, and is
normally not needed by class generators or adapters.
Parameters:
owner - the internal name of the field's owner class.
Parameters:
name - the field's name.
Parameters:
desc - the field's descriptor. | | Item | newFieldItem(String owner, String name, String desc)
Adds a field reference to the constant pool of the class being build.
Does nothing if the constant pool already contains a similar item.
Parameters:
owner - the internal name of the field's owner class.
Parameters:
name - the field's name.
Parameters:
desc - the field's descriptor. | | Item | newFloat(float value)
Adds a float to the constant pool of the class being build. | | Item | newInteger(int value)
Adds an integer to the constant pool of the class being build. | | Item | newLong(long value)
Adds a long to the constant pool of the class being build. | | public int | newMethod(String owner, String name, String desc, boolean itf)
Adds a method reference to the constant pool of the class being build.
Does nothing if the constant pool already contains a similar item.
This method is intended for
Attribute sub classes, and is
normally not needed by class generators or adapters.
Parameters:
owner - the internal name of the method's owner class.
Parameters:
name - the method's name.
Parameters:
desc - the method's descriptor.
Parameters:
itf - true if owner is an interface. | | Item | newMethodItem(String owner, String name, String desc, boolean itf)
Adds a method reference to the constant pool of the class being build.
Does nothing if the constant pool already contains a similar item.
Parameters:
owner - the internal name of the method's owner class.
Parameters:
name - the method's name.
Parameters:
desc - the method's descriptor.
Parameters:
itf - true if owner is an interface. | | public int | newNameType(String name, String desc)
Adds a name and type to the constant pool of the class being build. | | public int | newUTF8(String value)
Adds an UTF8 string to the constant pool of the class being build. | | public byte[] | toByteArray()
Returns the bytecode of the class that was build with this class writer. | | public void | visit(int version, int access, String name, String signature, String superName, String[] interfaces)
| | public AnnotationVisitor | visitAnnotation(String desc, boolean visible)
| | public void | visitAttribute(Attribute attr)
| | public void | visitEnd()
| | public FieldVisitor | visitField(int access, String name, String desc, String signature, Object value)
| | public void | visitInnerClass(String name, String outerName, String innerName, int access)
| | public MethodVisitor | visitMethod(int access, String name, String desc, String signature, String[] exceptions)
| | public void | visitOuterClass(String owner, String name, String desc)
| | public void | visitSource(String file, String debug)
|
| CLASS | | final static int CLASS(Code) | | The type of CONSTANT_Class constant pool items.
|
| COMPUTE_FRAMES | | final public static int COMPUTE_FRAMES(Code) | | Flag to automatically compute the stack map frames of methods from
scratch. If this flag is set, then the calls to the
MethodVisitor.visitFrame method are ignored, and the stack map
frames are recomputed from the methods bytecode. The arguments of the
MethodVisitor.visitMaxs visitMaxs method are also ignored and
recomputed from the bytecode. In other words, computeFrames implies
computeMaxs.
See Also: ClassWriter.ClassWriter(int) |
| DOUBLE | | final static int DOUBLE(Code) | | The type of CONSTANT_Double constant pool items.
|
| FIELD | | final static int FIELD(Code) | | The type of CONSTANT_Fieldref constant pool items.
|
| FIELDORMETH_INSN | | final static int FIELDORMETH_INSN(Code) | | The type of field and method invocations instructions.
|
| FLOAT | | final static int FLOAT(Code) | | The type of CONSTANT_Float constant pool items.
|
| IINC_INSN | | final static int IINC_INSN(Code) | | The type of the IINC instruction.
|
| IMETH | | final static int IMETH(Code) | | The type of CONSTANT_InterfaceMethodref constant pool items.
|
| IMPLVAR_INSN | | final static int IMPLVAR_INSN(Code) | | The type of instructions with an implicit local variable index argument.
|
| INT | | final static int INT(Code) | | The type of CONSTANT_Integer constant pool items.
|
| ITFMETH_INSN | | final static int ITFMETH_INSN(Code) | | The type of the INVOKEINTERFACE instruction.
|
| LABELW_INSN | | final static int LABELW_INSN(Code) | | The type of instructions with a 4 bytes bytecode offset label.
|
| LABEL_INSN | | final static int LABEL_INSN(Code) | | The type of instructions with a 2 bytes bytecode offset label.
|
| LDCW_INSN | | final static int LDCW_INSN(Code) | | The type of the LDC_W and LDC2_W instructions.
|
| LDC_INSN | | final static int LDC_INSN(Code) | | The type of the LDC instruction.
|
| LONG | | final static int LONG(Code) | | The type of CONSTANT_Long constant pool items.
|
| LOOK_INSN | | final static int LOOK_INSN(Code) | | The type of the LOOKUPSWITCH instruction.
|
| MANA_INSN | | final static int MANA_INSN(Code) | | The type of the MULTIANEWARRAY instruction.
|
| METH | | final static int METH(Code) | | The type of CONSTANT_Methodref constant pool items.
|
| NAME_TYPE | | final static int NAME_TYPE(Code) | | The type of CONSTANT_NameAndType constant pool items.
|
| NOARG_INSN | | final static int NOARG_INSN(Code) | | The type of instructions without any argument.
|
| SBYTE_INSN | | final static int SBYTE_INSN(Code) | | The type of instructions with an signed byte argument.
|
| SHORT_INSN | | final static int SHORT_INSN(Code) | | The type of instructions with an signed short argument.
|
| STR | | final static int STR(Code) | | The type of CONSTANT_String constant pool items.
|
| TABL_INSN | | final static int TABL_INSN(Code) | | The type of the TABLESWITCH instruction.
|
| TYPE | | static byte[] TYPE(Code) | | The instruction types of all JVM opcodes.
|
| TYPE_INSN | | final static int TYPE_INSN(Code) | | The type of instructions with a type descriptor argument.
|
| TYPE_MERGED | | final static int TYPE_MERGED(Code) | | Merged type Item stored in the ClassWriter
ClassWriter.typeTable ,
instead of the constant pool, in order to avoid clashes with normal
constant pool items in the ClassWriter constant pool's hash table.
|
| TYPE_NORMAL | | final static int TYPE_NORMAL(Code) | | Normal type Item stored in the ClassWriter
ClassWriter.typeTable ,
instead of the constant pool, in order to avoid clashes with normal
constant pool items in the ClassWriter constant pool's hash table.
|
| TYPE_UNINIT | | final static int TYPE_UNINIT(Code) | | Uninitialized type Item stored in the ClassWriter
ClassWriter.typeTable , instead of the constant pool, in order to
avoid clashes with normal constant pool items in the ClassWriter constant
pool's hash table.
|
| UTF8 | | final static int UTF8(Code) | | The type of CONSTANT_Utf8 constant pool items.
|
| VAR_INSN | | final static int VAR_INSN(Code) | | The type of instructions with a local variable index argument.
|
| WIDE_INSN | | final static int WIDE_INSN(Code) | | The type of the WIDE instruction.
|
| cr | | ClassReader cr(Code) | | The class reader from which this class writer was constructed, if any.
|
| firstField | | FieldWriter firstField(Code) | | The fields of this class. These fields are stored in a linked list of
FieldWriter objects, linked to each other by their
FieldWriter.next field. This field stores the first element of
this list.
|
| firstMethod | | MethodWriter firstMethod(Code) | | The methods of this class. These methods are stored in a linked list of
MethodWriter objects, linked to each other by their
MethodWriter.next field. This field stores the first element of
this list.
|
| index | | int index(Code) | | Index of the next item to be added in the constant pool.
|
| invalidFrames | | boolean invalidFrames(Code) | | true if the stack map tables of this class are invalid. The
MethodWriter.resizeInstructions method cannot transform existing
stack map tables, and so produces potentially invalid classes when it is
executed. In this case the class is reread and rewritten with the
ClassWriter.COMPUTE_FRAMES option (the resizeInstructions method can resize
stack map tables when this option is used).
|
| items | | Item[] items(Code) | | The constant pool's hash table data.
|
| lastField | | FieldWriter lastField(Code) | | The fields of this class. These fields are stored in a linked list of
FieldWriter objects, linked to each other by their
FieldWriter.next field. This field stores the last element of
this list.
|
| lastMethod | | MethodWriter lastMethod(Code) | | The methods of this class. These methods are stored in a linked list of
MethodWriter objects, linked to each other by their
MethodWriter.next field. This field stores the last element of
this list.
|
| thisName | | String thisName(Code) | | The internal name of this class.
|
| threshold | | int threshold(Code) | | The threshold of the constant pool's hash table.
|
| typeTable | | Item[] typeTable(Code) | | A type table used to temporarily store internal names that will not
necessarily be stored in the constant pool. This type table is used by
the control flow and data flow analysis algorithm used to compute stack
map frames from scratch. This array associates to each index i
the Item whose index is i. All Item objects stored in this
array are also stored in the
ClassWriter.items hash table. These two arrays
allow to retrieve an Item from its index or, conversly, to get the index
of an Item from its value. Each Item stores an internal name in its
Item.strVal1 field.
|
| version | | int version(Code) | | Minor and major version numbers of the class to be generated.
|
| ClassWriter | | public ClassWriter(ClassReader classReader, int flags)(Code) | | Constructs a new
ClassWriter object and enables optimizations for
"mostly add" bytecode transformations. These optimizations are the
following:
- The constant pool from the original class is copied as is in
the new class, which saves time. New constant pool entries will be added
at the end if necessary, but unused constant pool entries won't be
removed.
- Methods that are not transformed are copied as
is in the new class, directly from the original class bytecode (i.e.
without emitting visit events for all the method instructions), which
saves a lot of time. Untransformed methods are detected by the
fact that the
ClassReader receives
MethodVisitor objects
that come from a
ClassWriter (and not from a custom
ClassAdapter or any other
ClassVisitor instance).
Parameters:
classReader - the ClassReader used to read the originalclass. It will be used to copy the entire constant pool from theoriginal class and also to copy other fragments of originalbytecode where applicable.
Parameters:
flags - option flags that can be used to modify the default behaviorof this class. See ClassWriter.COMPUTE_MAXS, ClassWriter.COMPUTE_FRAMES. |
| addType | | int addType(String type)(Code) | | Adds the given internal name to
ClassWriter.typeTable and returns its index.
Does nothing if the type table already contains this internal name.
Parameters:
type - the internal name to be added to the type table. the index of this internal name in the type table. |
| addUninitializedType | | int addUninitializedType(String type, int offset)(Code) | | Adds the given "uninitialized" type to
ClassWriter.typeTable and returns its
index. This method is used for UNINITIALIZED types, made of an internal
name and a bytecode offset.
Parameters:
type - the internal name to be added to the type table.
Parameters:
offset - the bytecode offset of the NEW instruction that createdthis UNINITIALIZED type value. the index of this internal name in the type table. |
| getCommonSuperClass | | protected String getCommonSuperClass(String type1, String type2)(Code) | | Returns the common super type of the two given types. The default
implementation of this method loads the two given classes and uses
the java.lang.Class methods to find the common super class. It can be
overriden to compute this common super type in other ways, in particular
without actually loading any class, or to take into account the class
that is currently being generated by this ClassWriter, which can of
course not be loaded since it is under construction.
Parameters:
type1 - the internal name of a class.
Parameters:
type2 - the internal name of another class. the internal name of the common super class of the two givenclasses. |
| getMergedType | | int getMergedType(int type1, int type2)(Code) | | Returns the index of the common super type of the two given types. This
method calls
ClassWriter.getCommonSuperClass and caches the result in the
ClassWriter.items hash table to speedup future calls with the same
parameters.
Parameters:
type1 - index of an internal name in ClassWriter.typeTable.
Parameters:
type2 - index of an internal name in ClassWriter.typeTable. the index of the common super type of the two given types. |
| newClass | | public int newClass(String value)(Code) | | Adds a class reference to the constant pool of the class being build.
Does nothing if the constant pool already contains a similar item.
This method is intended for
Attribute sub classes, and is
normally not needed by class generators or adapters.
Parameters:
value - the internal name of the class. the index of a new or already existing class reference item. |
| newClassItem | | Item newClassItem(String value)(Code) | | Adds a class reference to the constant pool of the class being build.
Does nothing if the constant pool already contains a similar item.
This method is intended for
Attribute sub classes, and is
normally not needed by class generators or adapters.
Parameters:
value - the internal name of the class. a new or already existing class reference item. |
| newConst | | public int newConst(Object cst)(Code) | | Adds a number or string constant to the constant pool of the class being
build. Does nothing if the constant pool already contains a similar item.
This method is intended for
Attribute sub classes, and is
normally not needed by class generators or adapters.
Parameters:
cst - the value of the constant to be added to the constant pool.This parameter must be an Integer, a Float, aLong, a Double or a String. the index of a new or already existing constant item with thegiven value. |
| newConstItem | | Item newConstItem(Object cst)(Code) | | Adds a number or string constant to the constant pool of the class being
build. Does nothing if the constant pool already contains a similar item.
Parameters:
cst - the value of the constant to be added to the constant pool.This parameter must be an Integer, a Float, aLong, a Double, a String or aType. a new or already existing constant item with the given value. |
| newDouble | | Item newDouble(double value)(Code) | | Adds a double to the constant pool of the class being build. Does nothing
if the constant pool already contains a similar item.
Parameters:
value - the double value. a new or already existing double item. |
| newField | | public int newField(String owner, String name, String desc)(Code) | | Adds a field reference to the constant pool of the class being build.
Does nothing if the constant pool already contains a similar item.
This method is intended for
Attribute sub classes, and is
normally not needed by class generators or adapters.
Parameters:
owner - the internal name of the field's owner class.
Parameters:
name - the field's name.
Parameters:
desc - the field's descriptor. the index of a new or already existing field reference item. |
| newFieldItem | | Item newFieldItem(String owner, String name, String desc)(Code) | | Adds a field reference to the constant pool of the class being build.
Does nothing if the constant pool already contains a similar item.
Parameters:
owner - the internal name of the field's owner class.
Parameters:
name - the field's name.
Parameters:
desc - the field's descriptor. a new or already existing field reference item. |
| newFloat | | Item newFloat(float value)(Code) | | Adds a float to the constant pool of the class being build. Does nothing
if the constant pool already contains a similar item.
Parameters:
value - the float value. a new or already existing float item. |
| newInteger | | Item newInteger(int value)(Code) | | Adds an integer to the constant pool of the class being build. Does
nothing if the constant pool already contains a similar item.
Parameters:
value - the int value. a new or already existing int item. |
| newLong | | Item newLong(long value)(Code) | | Adds a long to the constant pool of the class being build. Does nothing
if the constant pool already contains a similar item.
Parameters:
value - the long value. a new or already existing long item. |
| newMethod | | public int newMethod(String owner, String name, String desc, boolean itf)(Code) | | Adds a method reference to the constant pool of the class being build.
Does nothing if the constant pool already contains a similar item.
This method is intended for
Attribute sub classes, and is
normally not needed by class generators or adapters.
Parameters:
owner - the internal name of the method's owner class.
Parameters:
name - the method's name.
Parameters:
desc - the method's descriptor.
Parameters:
itf - true if owner is an interface. the index of a new or already existing method reference item. |
| newMethodItem | | Item newMethodItem(String owner, String name, String desc, boolean itf)(Code) | | Adds a method reference to the constant pool of the class being build.
Does nothing if the constant pool already contains a similar item.
Parameters:
owner - the internal name of the method's owner class.
Parameters:
name - the method's name.
Parameters:
desc - the method's descriptor.
Parameters:
itf - true if owner is an interface. a new or already existing method reference item. |
| newNameType | | public int newNameType(String name, String desc)(Code) | | Adds a name and type to the constant pool of the class being build. Does
nothing if the constant pool already contains a similar item. This
method is intended for
Attribute sub classes, and is normally not
needed by class generators or adapters.
Parameters:
name - a name.
Parameters:
desc - a type descriptor. the index of a new or already existing name and type item. |
| newUTF8 | | public int newUTF8(String value)(Code) | | Adds an UTF8 string to the constant pool of the class being build. Does
nothing if the constant pool already contains a similar item. This
method is intended for
Attribute sub classes, and is normally not
needed by class generators or adapters.
Parameters:
value - the String value. the index of a new or already existing UTF8 item. |
| toByteArray | | public byte[] toByteArray()(Code) | | Returns the bytecode of the class that was build with this class writer.
the bytecode of the class that was build with this class writer. |
| visitEnd | | public void visitEnd()(Code) | | |
|
|