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

  • Method Summary

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

    Methods inherited from class org.objectweb.asm.ClassVisitor

    getDelegate, 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 Details

    • 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:
      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 the ASMx values in Opcodes.
      classVisitor - a ClassVisitor to which this visitor will delegate calls.

  • Method Details

    • visit

      public void visit(int version, int access, String name, String signature, String superName, String[] interfaces)
      Overrides:
      visit in class org.objectweb.asm.ClassVisitor

    • visitMethod

      public org.objectweb.asm.MethodVisitor visitMethod(int access, String name, String descriptor, String signature, String[] exceptions)
      Overrides:
      visitMethod in class org.objectweb.asm.ClassVisitor

    • visitField

      public org.objectweb.asm.FieldVisitor visitField(int access, String name, String desc, String signature, Object value)
      Overrides:
      visitField in class org.objectweb.asm.ClassVisitor

    • visitInnerClass

      public void visitInnerClass(String innerClassName, String outerName, 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 IOException
      Computes and returns the value of SVUID.
      Returns:
      the serial version UID.
      Throws:
      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.