类 ClassWriter
- java.lang.Object
- org.springframework.asm.ClassVisitor
- org.springframework.asm.ClassWriter
public class ClassWriter extends ClassVisitor
AClassVisitor
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 moreClassReader
and adapter class visitor to generate a modified class from one or more existing Java classes.- 作者:
- Eric Bruneton
字段概要
字段 修饰符和类型 字段 说明 static int
COMPUTE_FRAMES
Flag to automatically compute the stack map frames of methods from scratch.static int
COMPUTE_MAXS
Flag to automatically compute the maximum stack size and the maximum number of local variables of methods.从类继承的字段 org.springframework.asm.ClassVisitor
api, cv
构造器概要
构造器 构造器 说明 ClassWriter(int flags)
Constructs a newClassWriter
object.ClassWriter(ClassReader classReader, int flags)
Constructs a newClassWriter
object and enables optimizations for "mostly add" bytecode transformations.
方法概要
所有方法 实例方法 具体方法 已过时的方法 修饰符和类型 方法 说明 protected ClassLoader
getClassLoader()
protected String
getCommonSuperClass(String type1, String type2)
Returns the common super type of the two given types.int
newClass(String value)
Adds a class reference to the constant pool of the class being build.int
newConst(Object cst)
Adds a number or string constant to the constant pool of the class being build.int
newField(String owner, String name, String desc)
Adds a field reference to the constant pool of the class being build.int
newHandle(int tag, String owner, String name, String desc)
已过时。this method is superseded bynewHandle(int, String, String, String, boolean)
.int
newHandle(int tag, String owner, String name, String desc, boolean itf)
Adds a handle to the constant pool of the class being build.int
newInvokeDynamic(String name, String desc, Handle bsm, Object... bsmArgs)
Adds an invokedynamic reference to the constant pool of the class being build.int
newMethod(String owner, String name, String desc, boolean itf)
Adds a method reference to the constant pool of the class being build.int
newMethodType(String methodDesc)
Adds a method type reference to the constant pool of the class being build.int
newModule(String moduleName)
Adds a module reference to the constant pool of the class being build.int
newNameType(String name, String desc)
Adds a name and type to the constant pool of the class being build.int
newPackage(String packageName)
Adds a package reference to the constant pool of the class being build.int
newUTF8(String value)
Adds an UTF8 string to the constant pool of the class being build.byte[]
toByteArray()
Returns the bytecode of the class that was build with this class writer.void
visit(int version, int access, String name, String signature, String superName, String[] interfaces)
Visits the header of the class.AnnotationVisitor
visitAnnotation(String desc, boolean visible)
Visits an annotation of the class.void
visitAttribute(Attribute attr)
Visits a non standard attribute of the class.void
visitEnd()
Visits the end of the class.FieldVisitor
visitField(int access, String name, String desc, String signature, Object value)
Visits a field of the class.void
visitInnerClass(String name, String outerName, String innerName, int access)
Visits information about an inner class.MethodVisitor
visitMethod(int access, String name, String desc, String signature, String[] exceptions)
Visits a method of the class.ModuleVisitor
visitModule(String name, int access, String version)
Visit the module corresponding to the class.void
visitOuterClass(String owner, String name, String desc)
Visits the enclosing class of the class.void
visitSource(String file, String debug)
Visits the source of the class.AnnotationVisitor
visitTypeAnnotation(int typeRef, TypePath typePath, String desc, boolean visible)
Visits an annotation on a type in the class signature.
字段详细资料
COMPUTE_MAXS
public static final int COMPUTE_MAXS
Flag to automatically compute the maximum stack size and the maximum number of local variables of methods. If this flag is set, then the arguments of thevisitMaxs
method of theMethodVisitor
returned by thevisitMethod
method will be ignored, and computed automatically from the signature and the bytecode of each method.- 另请参阅:
ClassWriter(int)
, 常量字段值
COMPUTE_FRAMES
public static final int COMPUTE_FRAMES
Flag to automatically compute the stack map frames of methods from scratch. If this flag is set, then the calls to theMethodVisitor.visitFrame(int, int, java.lang.Object[], int, java.lang.Object[])
method are ignored, and the stack map frames are recomputed from the methods bytecode. The arguments of thevisitMaxs
method are also ignored and recomputed from the bytecode. In other words, COMPUTE_FRAMES implies COMPUTE_MAXS.- 另请参阅:
ClassWriter(int)
, 常量字段值
构造器详细资料
ClassWriter
public ClassWriter(int flags)
Constructs a newClassWriter
object.- 参数:
flags
- option flags that can be used to modify the default behavior of this class. SeeCOMPUTE_MAXS
,COMPUTE_FRAMES
.
ClassWriter
public ClassWriter(ClassReader classReader, int flags)
Constructs a newClassWriter
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
receivesMethodVisitor
objects that come from aClassWriter
(and not from any otherClassVisitor
instance).
- 参数:
classReader
- theClassReader
used to read the original class. It will be used to copy the entire constant pool from the original class and also to copy other fragments of original bytecode where applicable.flags
- option flags that can be used to modify the default behavior of this class. These option flags do not affect methods that are copied as is in the new class. This means that neither the maximum stack size nor the stack frames will be computed for these methods. SeeCOMPUTE_MAXS
,COMPUTE_FRAMES
.
方法详细资料
visit
public final void visit(int version, int access, String name, String signature, String superName, String[] interfaces)
从类复制的说明:ClassVisitor
Visits the header of the class.- 覆盖:
visit
在类中ClassVisitor
- 参数:
version
- the class version.access
- the class's access flags (seeOpcodes
). This parameter also indicates if the class is deprecated.name
- the internal name of the class (seegetInternalName
).signature
- the signature of this class. May be null if the class is not a generic one, and does not extend or implement generic classes or interfaces.superName
- the internal of name of the super class (seegetInternalName
). For interfaces, the super class isObject
. May be null, but only for theObject
class.interfaces
- the internal names of the class's interfaces (seegetInternalName
). May be null.
visitSource
public final void visitSource(String file, String debug)
从类复制的说明:ClassVisitor
Visits the source of the class.- 覆盖:
visitSource
在类中ClassVisitor
- 参数:
file
- the name of the source file from which the class was compiled. May be null.debug
- additional debug information to compute the correspondance between source and compiled elements of the class. May be null.
visitModule
public final ModuleVisitor visitModule(String name, int access, String version)
从类复制的说明:ClassVisitor
Visit the module corresponding to the class.- 覆盖:
visitModule
在类中ClassVisitor
- 参数:
name
- module nameaccess
- module flags, amongACC_OPEN
,ACC_SYNTHETIC
andACC_MANDATED
.version
- module version or null.- 返回:
- a visitor to visit the module values, or null if this visitor is not interested in visiting this module.
visitOuterClass
public final void visitOuterClass(String owner, String name, String desc)
从类复制的说明:ClassVisitor
Visits the enclosing class of the class. This method must be called only if the class has an enclosing class.- 覆盖:
visitOuterClass
在类中ClassVisitor
- 参数:
owner
- internal name of the enclosing class of the class.name
- the name of the method that contains the class, or null if the class is not enclosed in a method of its enclosing class.desc
- the descriptor of the method that contains the class, or null if the class is not enclosed in a method of its enclosing class.
visitAnnotation
public final AnnotationVisitor visitAnnotation(String desc, boolean visible)
从类复制的说明:ClassVisitor
Visits an annotation of the class.- 覆盖:
visitAnnotation
在类中ClassVisitor
- 参数:
desc
- the class descriptor of the annotation class.visible
- true if the annotation is visible at runtime.- 返回:
- a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.
visitTypeAnnotation
public final AnnotationVisitor visitTypeAnnotation(int typeRef, TypePath typePath, String desc, boolean visible)
从类复制的说明:ClassVisitor
Visits an annotation on a type in the class signature.- 覆盖:
visitTypeAnnotation
在类中ClassVisitor
- 参数:
typeRef
- a reference to the annotated type. The sort of this type reference must beCLASS_TYPE_PARAMETER
,CLASS_TYPE_PARAMETER_BOUND
orCLASS_EXTENDS
. SeeTypeReference
.typePath
- the path to the annotated type argument, wildcard bound, array element type, or static inner type within 'typeRef'. May be null if the annotation targets 'typeRef' as a whole.desc
- the class descriptor of the annotation class.visible
- true if the annotation is visible at runtime.- 返回:
- a visitor to visit the annotation values, or null if this visitor is not interested in visiting this annotation.
visitAttribute
public final void visitAttribute(Attribute attr)
从类复制的说明:ClassVisitor
Visits a non standard attribute of the class.- 覆盖:
visitAttribute
在类中ClassVisitor
- 参数:
attr
- an attribute.
visitInnerClass
public final void visitInnerClass(String name, String outerName, String innerName, int access)
从类复制的说明:ClassVisitor
Visits information about an inner class. This inner class is not necessarily a member of the class being visited.- 覆盖:
visitInnerClass
在类中ClassVisitor
- 参数:
name
- the internal name of an inner class (seegetInternalName
).outerName
- the internal name of the class to which the inner class belongs (seegetInternalName
). May be null for not member classes.innerName
- the (simple) name of the inner class inside its enclosing class. May be null for anonymous inner classes.access
- the access flags of the inner class as originally declared in the enclosing class.
visitField
public final FieldVisitor visitField(int access, String name, String desc, String signature, Object value)
从类复制的说明:ClassVisitor
Visits a field of the class.- 覆盖:
visitField
在类中ClassVisitor
- 参数:
access
- the field's access flags (seeOpcodes
). This parameter also indicates if the field is synthetic and/or deprecated.name
- the field's name.desc
- the field's descriptor (seeType
).signature
- the field's signature. May be null if the field's type does not use generic types.value
- the field's initial value. This parameter, which may be null if the field does not have an initial value, must be anInteger
, aFloat
, aLong
, aDouble
or aString
(for int, float, long or String fields respectively). This parameter is only used for static fields. Its value is ignored for non static fields, which must be initialized through bytecode instructions in constructors or methods.- 返回:
- a visitor to visit field annotations and attributes, or null if this class visitor is not interested in visiting these annotations and attributes.
visitMethod
public final MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions)
从类复制的说明:ClassVisitor
Visits a method of the class. This method must return a newMethodVisitor
instance (or null) each time it is called, i.e., it should not return a previously returned visitor.- 覆盖:
visitMethod
在类中ClassVisitor
- 参数:
access
- the method's access flags (seeOpcodes
). This parameter also indicates if the method is synthetic and/or deprecated.name
- the method's name.desc
- the method's descriptor (seeType
).signature
- the method's signature. May be null if the method parameters, return type and exceptions do not use generic types.exceptions
- the internal names of the method's exception classes (seegetInternalName
). May be null.- 返回:
- an object to visit the byte code of the method, or null if this class visitor is not interested in visiting the code of this method.
visitEnd
public final void visitEnd()
从类复制的说明:ClassVisitor
Visits the end of the class. This method, which is the last one to be called, is used to inform the visitor that all the fields and methods of the class have been visited.- 覆盖:
visitEnd
在类中ClassVisitor
toByteArray
public byte[] toByteArray()
Returns the bytecode of the class that was build with this class writer.- 返回:
- the bytecode of the class that was build with this class writer.
newConst
public int newConst(Object cst)
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 forAttribute
sub classes, and is normally not needed by class generators or adapters.
newUTF8
public int newUTF8(String value)
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 forAttribute
sub classes, and is normally not needed by class generators or adapters.- 参数:
value
- the String value.- 返回:
- the index of a new or already existing UTF8 item.
newClass
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 forAttribute
sub classes, and is normally not needed by class generators or adapters.- 参数:
value
- the internal name of the class.- 返回:
- the index of a new or already existing class reference item.
newMethodType
public int newMethodType(String methodDesc)
Adds a method type 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 forAttribute
sub classes, and is normally not needed by class generators or adapters.- 参数:
methodDesc
- method descriptor of the method type.- 返回:
- the index of a new or already existing method type reference item.
newModule
public int newModule(String moduleName)
Adds a module 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 forAttribute
sub classes, and is normally not needed by class generators or adapters.- 参数:
moduleName
- name of the module.- 返回:
- the index of a new or already existing module reference item.
newPackage
public int newPackage(String packageName)
Adds a package 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 forAttribute
sub classes, and is normally not needed by class generators or adapters.- 参数:
packageName
- name of the package in its internal form.- 返回:
- the index of a new or already existing module reference item.
newHandle
@Deprecated public int newHandle(int tag, String owner, String name, String desc)
已过时。this method is superseded bynewHandle(int, String, String, String, boolean)
.Adds a handle to the constant pool of the class being build. Does nothing if the constant pool already contains a similar item. This method is intended forAttribute
sub classes, and is normally not needed by class generators or adapters.- 参数:
tag
- the kind of this handle. Must beOpcodes.H_GETFIELD
,Opcodes.H_GETSTATIC
,Opcodes.H_PUTFIELD
,Opcodes.H_PUTSTATIC
,Opcodes.H_INVOKEVIRTUAL
,Opcodes.H_INVOKESTATIC
,Opcodes.H_INVOKESPECIAL
,Opcodes.H_NEWINVOKESPECIAL
orOpcodes.H_INVOKEINTERFACE
.owner
- the internal name of the field or method owner class.name
- the name of the field or method.desc
- the descriptor of the field or method.- 返回:
- the index of a new or already existing method type reference item.
newHandle
public int newHandle(int tag, String owner, String name, String desc, boolean itf)
Adds a handle to the constant pool of the class being build. Does nothing if the constant pool already contains a similar item. This method is intended forAttribute
sub classes, and is normally not needed by class generators or adapters.- 参数:
tag
- the kind of this handle. Must beOpcodes.H_GETFIELD
,Opcodes.H_GETSTATIC
,Opcodes.H_PUTFIELD
,Opcodes.H_PUTSTATIC
,Opcodes.H_INVOKEVIRTUAL
,Opcodes.H_INVOKESTATIC
,Opcodes.H_INVOKESPECIAL
,Opcodes.H_NEWINVOKESPECIAL
orOpcodes.H_INVOKEINTERFACE
.owner
- the internal name of the field or method owner class.name
- the name of the field or method.desc
- the descriptor of the field or method.itf
- true if the owner is an interface.- 返回:
- the index of a new or already existing method type reference item.
newInvokeDynamic
public int newInvokeDynamic(String name, String desc, Handle bsm, Object... bsmArgs)
Adds an invokedynamic 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 forAttribute
sub classes, and is normally not needed by class generators or adapters.- 参数:
name
- name of the invoked method.desc
- descriptor of the invoke method.bsm
- the bootstrap method.bsmArgs
- the bootstrap method constant arguments.- 返回:
- the index of a new or already existing invokedynamic reference item.
newField
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 forAttribute
sub classes, and is normally not needed by class generators or adapters.- 参数:
owner
- the internal name of the field's owner class.name
- the field's name.desc
- the field's descriptor.- 返回:
- the index of a new or already existing field reference item.
newMethod
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 forAttribute
sub classes, and is normally not needed by class generators or adapters.- 参数:
owner
- the internal name of the method's owner class.name
- the method's name.desc
- the method's descriptor.itf
- true if owner is an interface.- 返回:
- the index of a new or already existing method reference item.
newNameType
public int newNameType(String name, String desc)
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 forAttribute
sub classes, and is normally not needed by class generators or adapters.- 参数:
name
- a name.desc
- a type descriptor.- 返回:
- the index of a new or already existing name and type item.
getCommonSuperClass
protected String getCommonSuperClass(String type1, String type2)
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 overridden 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.- 参数:
type1
- the internal name of a class.type2
- the internal name of another class.- 返回:
- the internal name of the common super class of the two given classes.
getClassLoader
protected ClassLoader getClassLoader()