org.objectweb.asm.commons

Class SerialVersionUIDAdder

java.lang.Object

org.objectweb.asm.ClassVisitor

org.objectweb.asm.commons.SerialVersionUIDAdder

public class SerialVersionUIDAdder
extends org.objectweb.asm.ClassVisitor

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:

1. The class name written using UTF encoding.
2. The class modifiers written as a 32-bit integer.
3. The name of each interface sorted by name written using UTF encoding.
4. For each field of the class sorted by field name (except private static and private transient fields):
   1. The name of the field in UTF encoding.
   2. The modifiers of the field written as a 32-bit integer.
   3. The descriptor of the field in UTF encoding
5. If a class initializer exists, write out the following:
   1. The name of the method, <clinit>, in UTF encoding.
   2. The modifier of the method, STATIC, written as a 32-bit integer.
   3. The descriptor of the method, ()V, in UTF encoding.
6. For each non-private constructor sorted by method name and signature:
   1. The name of the method, <init>, in UTF encoding.
   2. The modifiers of the method written as a 32-bit integer.
   3. The descriptor of the method in UTF encoding.
7. For each non-private method sorted by method name and signature:
   1. The name of the method in UTF encoding.
   2. The modifiers of the method written as a 32-bit integer.
   3. The descriptor of the method in UTF encoding.
8. The SHA-1 algorithm is executed on the stream of bytes produced by DataOutputStream and produces five 32-bit values sha[0..4].
9. 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;

Field Summary

Fields inherited from class org.objectweb.asm.ClassVisitor

api, cv

Constructor Summary

Constructors

Modifier	Constructor and Description
	SerialVersionUIDAdder(org.objectweb.asm.ClassVisitor classVisitor) Constructs a new SerialVersionUIDAdder.
protected	SerialVersionUIDAdder(int api, org.objectweb.asm.ClassVisitor classVisitor) Constructs a new SerialVersionUIDAdder.

Method Summary

Modifier and Type	Method and Description
protected 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	computeSVUID() 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, java.lang.String name, java.lang.String signature, java.lang.String superName, java.lang.String[] interfaces)
void	visitEnd()
org.objectweb.asm.FieldVisitor	visitField(int access, java.lang.String name, java.lang.String desc, java.lang.String signature, java.lang.Object value)
void	visitInnerClass(java.lang.String innerClassName, java.lang.String outerName, java.lang.String innerName, int innerClassAccess)
org.objectweb.asm.MethodVisitor	visitMethod(int access, java.lang.String name, java.lang.String descriptor, java.lang.String signature, java.lang.String[] exceptions)

Methods inherited from class org.objectweb.asm.ClassVisitor

visitAnnotation, visitAttribute, visitModule, visitNestHost, visitNestMember, visitOuterClass, visitPermittedSubclass, visitRecordComponent, visitSource, visitTypeAnnotation

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SerialVersionUIDAdder

public SerialVersionUIDAdder(org.objectweb.asm.ClassVisitor classVisitor)

Constructs a new SerialVersionUIDAdder. Subclasses must not use this constructor. Instead, they must use the SerialVersionUIDAdder(int, ClassVisitor) version.

Parameters:

classVisitor - a ClassVisitor to which this visitor will delegate calls.

Throws:

java.lang.IllegalStateException - If a subclass calls this constructor.

SerialVersionUIDAdder

protected SerialVersionUIDAdder(int api,
                                org.objectweb.asm.ClassVisitor classVisitor)

Constructs a new SerialVersionUIDAdder.

Parameters:

api - the ASM API version implemented by this visitor. Must be one of Opcodes.ASM4, Opcodes.ASM5, Opcodes.ASM6, Opcodes.ASM7, Opcodes.ASM8 or Opcodes.ASM9.

classVisitor - a ClassVisitor to which this visitor will delegate calls.

Method Detail

visit

public void visit(int version,
                  int access,
                  java.lang.String name,
                  java.lang.String signature,
                  java.lang.String superName,
                  java.lang.String[] interfaces)

Overrides:

visit in class org.objectweb.asm.ClassVisitor

visitMethod

public org.objectweb.asm.MethodVisitor visitMethod(int access,
                                                   java.lang.String name,
                                                   java.lang.String descriptor,
                                                   java.lang.String signature,
                                                   java.lang.String[] exceptions)

Overrides:

visitMethod in class org.objectweb.asm.ClassVisitor

visitField

public org.objectweb.asm.FieldVisitor visitField(int access,
                                                 java.lang.String name,
                                                 java.lang.String desc,
                                                 java.lang.String signature,
                                                 java.lang.Object value)

Overrides:

visitField in class org.objectweb.asm.ClassVisitor

visitInnerClass

public void visitInnerClass(java.lang.String innerClassName,
                            java.lang.String outerName,
                            java.lang.String innerName,
                            int innerClassAccess)

Overrides:

visitInnerClass in class org.objectweb.asm.ClassVisitor

visitEnd

public void visitEnd()

Overrides:

visitEnd in class org.objectweb.asm.ClassVisitor

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.

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.

computeSVUID

protected long computeSVUID()
                     throws java.io.IOException

Computes and returns the value of SVUID.

Returns:

the serial version UID.

Throws:

java.io.IOException - if an I/O error occurs.

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.