Package org.objectweb.asm.commons
Class SerialVersionUIDAdder
java.lang.Object
org.objectweb.asm.ClassVisitor
org.objectweb.asm.commons.SerialVersionUIDAdder
A
ClassVisitor
that adds a serial version unique identifier to a class if missing. A
typical usage of this class is:
ClassWriter classWriter = new ClassWriter(...); ClassVisitor svuidAdder = new SerialVersionUIDAdder(classWriter); ClassVisitor classVisitor = new MyClassAdapter(svuidAdder); new ClassReader(orginalClass).accept(classVisitor, 0);
The SVUID algorithm can be found at https://docs.oracle.com/javase/10/docs/specs/serialization/class.html#stream-unique-identifiers:
The serialVersionUID is computed using the signature of a stream of bytes that reflect the class definition. The National Institute of Standards and Technology (NIST) Secure Hash Algorithm (SHA-1) is used to compute a signature for the stream. The first two 32-bit quantities are used to form a 64-bit hash. A java.lang.DataOutputStream is used to convert primitive data types to a sequence of bytes. The values input to the stream are defined by the Java Virtual Machine (VM) specification for classes.
The sequence of items in the stream is as follows:
- The class name written using UTF encoding.
- The class modifiers written as a 32-bit integer.
- The name of each interface sorted by name written using UTF encoding.
- For each field of the class sorted by field name (except private static and private
transient fields):
- The name of the field in UTF encoding.
- The modifiers of the field written as a 32-bit integer.
- The descriptor of the field in UTF encoding
- If a class initializer exists, write out the following:
- The name of the method, <clinit>, in UTF encoding.
- The modifier of the method, STATIC, written as a 32-bit integer.
- The descriptor of the method, ()V, in UTF encoding.
- For each non-private constructor sorted by method name and signature:
- The name of the method, <init>, in UTF encoding.
- The modifiers of the method written as a 32-bit integer.
- The descriptor of the method in UTF encoding.
- For each non-private method sorted by method name and signature:
- The name of the method in UTF encoding.
- The modifiers of the method written as a 32-bit integer.
- The descriptor of the method in UTF encoding.
- The SHA-1 algorithm is executed on the stream of bytes produced by DataOutputStream and produces five 32-bit values sha[0..4].
- The hash value is assembled from the first and second 32-bit values of the SHA-1 message digest. If the result of the message digest, the five 32-bit words H0 H1 H2 H3 H4, is in an array of five int values named sha, the hash value would be computed as follows: long hash = ((sha[0] >>> 24) & 0xFF) | ((sha[0] >>> 16) & 0xFF) << 8 | ((sha[0] >>> 8) & 0xFF) << 16 | ((sha[0] >>> 0) & 0xFF) << 24 | ((sha[1] >>> 24) & 0xFF) << 32 | ((sha[1] >>> 16) & 0xFF) << 40 | ((sha[1] >>> 8) & 0xFF) << 48 | ((sha[1] >>> 0) & 0xFF) << 56;
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Field Summary
Fields inherited from class org.objectweb.asm.ClassVisitor
api, cv
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Constructor Summary
ModifierConstructorDescriptionprotected
SerialVersionUIDAdder
(int api, ClassVisitor classVisitor) Constructs a newSerialVersionUIDAdder
.SerialVersionUIDAdder
(ClassVisitor classVisitor) Constructs a newSerialVersionUIDAdder
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Method Summary
Modifier and TypeMethodDescriptionprotected void
addSVUID
(long svuid) Adds a final static serialVersionUID field to the class, with the given value.protected byte[]
computeSHAdigest
(byte[] value) Returns the SHA-1 message digest of the given value.protected long
Computes and returns the value of SVUID.boolean
hasSVUID()
Returns true if the class already has a SVUID field.void
visit
(int version, int access, String name, String signature, String superName, String[] interfaces) Visits the header of the class.void
visitEnd()
Visits the end of the class.visitField
(int access, String name, String desc, String signature, Object value) Visits a field of the class.void
visitInnerClass
(String innerClassName, String outerName, String innerName, int innerClassAccess) Visits information about an inner class.visitMethod
(int access, String name, String descriptor, String signature, String[] exceptions) Visits a method of the class.Methods inherited from class org.objectweb.asm.ClassVisitor
getDelegate, visitAnnotation, visitAttribute, visitModule, visitNestHost, visitNestMember, visitOuterClass, visitPermittedSubclass, visitRecordComponent, visitSource, visitTypeAnnotation
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Constructor Details
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SerialVersionUIDAdder
Constructs a newSerialVersionUIDAdder
. Subclasses must not use this constructor. Instead, they must use theSerialVersionUIDAdder(int, ClassVisitor)
version.- Parameters:
classVisitor
- aClassVisitor
to which this visitor will delegate calls.- Throws:
IllegalStateException
- If a subclass calls this constructor.
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SerialVersionUIDAdder
Constructs a newSerialVersionUIDAdder
.- Parameters:
api
- the ASM API version implemented by this visitor. Must be one of theASM
x values inOpcodes
.classVisitor
- aClassVisitor
to which this visitor will delegate calls.
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Method Details
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visit
public void visit(int version, int access, String name, String signature, String superName, String[] interfaces) Description copied from class:ClassVisitor
Visits the header of the class.- Overrides:
visit
in classClassVisitor
- Parameters:
version
- the class version. The minor version is stored in the 16 most significant bits, and the major version in the 16 least significant bits.access
- the class's access flags (seeOpcodes
). This parameter also indicates if the class is deprecatedOpcodes.ACC_DEPRECATED
or a recordOpcodes.ACC_RECORD
.name
- the internal name of the class (seeType.getInternalName()
).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 (seeType.getInternalName()
). For interfaces, the super class isObject
. May be null, but only for theObject
class.interfaces
- the internal names of the class's interfaces (seeType.getInternalName()
). May be null.
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visitMethod
public MethodVisitor visitMethod(int access, String name, String descriptor, String signature, String[] exceptions) Description copied from class: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.- Overrides:
visitMethod
in classClassVisitor
- Parameters:
access
- the method's access flags (seeOpcodes
). This parameter also indicates if the method is synthetic and/or deprecated.name
- the method's name.descriptor
- 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 (seeType.getInternalName()
). May be null.- Returns:
- 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.
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visitField
public FieldVisitor visitField(int access, String name, String desc, String signature, Object value) Description copied from class:ClassVisitor
Visits a field of the class.- Overrides:
visitField
in classClassVisitor
- Parameters:
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
(forint
,float
,long
orString
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.- Returns:
- a visitor to visit field annotations and attributes, or null if this class visitor is not interested in visiting these annotations and attributes.
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visitInnerClass
public void visitInnerClass(String innerClassName, String outerName, String innerName, int innerClassAccess) Description copied from class:ClassVisitor
Visits information about an inner class. This inner class is not necessarily a member of the class being visited. More precisely, every class or interface C which is referenced by this class and which is not a package member must be visited with this method. This class must reference its nested class or interface members, and its enclosing class, if any. See the JVMS 4.7.6 section for more details.- Overrides:
visitInnerClass
in classClassVisitor
- Parameters:
innerClassName
- the internal name of C (seeType.getInternalName()
).outerName
- the internal name of the class or interface C is a member of (seeType.getInternalName()
). Must be null if C is not the member of a class or interface (e.g. for local or anonymous classes).innerName
- the (simple) name of C. Must be null for anonymous inner classes.innerClassAccess
- the access flags of C originally declared in the source code from which this class was compiled.
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visitEnd
public void visitEnd()Description copied from class: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.- Overrides:
visitEnd
in classClassVisitor
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hasSVUID
public boolean hasSVUID()Returns true if the class already has a SVUID field. The result of this method is only valid when visitEnd has been called.- Returns:
- true if the class already has a SVUID field.
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addSVUID
protected void addSVUID(long svuid) Adds a final static serialVersionUID field to the class, with the given value.- Parameters:
svuid
- the serialVersionUID field value.
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computeSVUID
Computes and returns the value of SVUID.- Returns:
- the serial version UID.
- Throws:
IOException
- if an I/O error occurs.
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computeSHAdigest
protected byte[] computeSHAdigest(byte[] value) Returns the SHA-1 message digest of the given value.- Parameters:
value
- the value whose SHA message digest must be computed.- Returns:
- the SHA-1 message digest of the given value.
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