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Java中类似于C语言中Sizeof功能实现(二)

2019-11-18 10:49:31
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  在做了所有这些预备之后,下面就是这种图形遍历的标准实现:
  public static IObjectPRofileNode profile (Object obj)
  {
  final IdentityHashMap visited = new IdentityHashMap ();
  
  final ObjectProfileNode root = createProfileTree (obj, visited,
  CLASS_METADATA_CACHE);
  finishProfileTree (root);
  
  return root;
  }
  
  private static ObjectProfileNode createProfileTree (Object obj,
  IdentityHashMap visited,
  Map metadataMap)
  {
  final ObjectProfileNode root = new ObjectProfileNode (null, obj, null);
  
  final LinkedList queue = new LinkedList ();
  
  queue.addFirst (root);
  visited.put (obj, root);
  
  final ClassaccessPrivilegedAction caAction =
  new ClassAccessPrivilegedAction ();
  final FieldAccessPrivilegedAction faAction =
  new FieldAccessPrivilegedAction ();
  
  while (! queue.isEmpty ())
  {
  final ObjectProfileNode node = (ObjectProfileNode) queue.removeFirst ();
  
  obj = node.m_obj;
  final Class objClass = obj.getClass ();
  
  if (objClass.isArray ())
  {
  final int arrayLength = Array.getLength (obj);
  final Class componentType = objClass.getComponentType ();
  
  // Add shell pseudo-node:
  final AbstractShellProfileNode shell =
  new ArrayShellProfileNode (node, objClass, arrayLength);
  shell.m_size = sizeofArrayShell (arrayLength, componentType);
  
  node.m_shell = shell;
  node.addFieldRef (shell);
  
  if (! componentType.isPrimitive ())
  {
  // Traverse each array slot:
  for (int i = 0; i < arrayLength; ++ i)
  {
  final Object ref = Array.get (obj, i);
  
  if (ref != null)
  {
  ObjectProfileNode child =
  (ObjectProfileNode) visited.get (ref);
  if (child != null)
  ++ child.m_refcount;
  else
  {
  child = new ObjectProfileNode (node, ref,
  new ArrayIndexLink (node.m_link, i));
  node.addFieldRef (child);
  
  queue.addLast (child);
  visited.put (ref, child);
  }
  }
  }
  }
  }
  else // the object is of a non-array type
  {
  final ClassMetadata metadata =
  getClassMetadata (objClass, metadataMap, caAction, faAction);
  final Field [] fields = metadata.m_refFields;
  
  // Add shell pseudo-node:
  final AbstractShellProfileNode shell =
  new ObjectShellProfileNode (node,
  metadata.m_primitiveFieldCount,
  metadata.m_refFields.length);
  shell.m_size = metadata.m_shellSize;
  
  node.m_shell = shell;
  node.addFieldRef (shell);
  
  // Traverse all non-null ref fields:
  for (int f = 0, fLimit = fields.length; f < fLimit; ++ f)
  {
  final Field field = fields [f];
  
  final Object ref;
  try // to get the field value:
  {
  ref = field.get (obj);
  }
  catch (Exception e)
  {
  throw new RuntimeException ("cannot get field [" +
  field.getName () + "] of class [" +
  field.getDeclaringClass ().getName () +
  "]: " + e.toString ());
  }
  
  if (ref != null)
  {
  ObjectProfileNode child =
  (ObjectProfileNode) visited.get (ref);
  if (child != null)
  ++ child.m_refcount;
  else
  {
  child = new ObjectProfileNode (node, ref,
  new ClassFieldLink (field));
  node.addFieldRef (child);
  
  queue.addLast (child);
  visited.put (ref, child);
  }
  }
  }
  }
  }
  
  return root;
  }
  
  private static void finishProfileTree (ObjectProfileNode node)
  {
  final LinkedList queue = new LinkedList ();
  IObjectProfileNode lastFinished = null;
  
  while (node != null)
  {
  // Note that an unfinished nonshell node has its child count
  // in m_size and m_children[0] is its shell node:
  
  if ((node.m_size == 1) (lastFinished == node.m_children [1]))
  {
  node.finish ();
  lastFinished = node;
  }
  else
  {
  queue.addFirst (node);
  for (int i = 1; i < node.m_size; ++ i)
  {
  final IObjectProfileNode child = node.m_children [i];
  queue.addFirst (child);
  }
  }
  
  if (queue.isEmpty ())
  return;
  else
  node = (ObjectProfileNode) queue.removeFirst ();
  }
  }
  
  该代码是上一篇java Q&A, "Attack of the Clones."使用的"通过反射克隆"实现的远亲。

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