在做了所有这些准备之后
public static IObjectProfileNode profile (Object obj)
{
final IdentityHashMap visited = new IdentityHashMap ();
final ObjectProfileNode root = createProfileTree (obj
CLASS_METADATA_CACHE);
finishProfileTree (root);
return root;
}
private static ObjectProfileNode createProfileTree (Object obj
IdentityHashMap visited
Map metadataMap)
{
final ObjectProfileNode root = new ObjectProfileNode (null
final LinkedList queue = new LinkedList ();
queue
visited
final ClassAccessPrivilegedAction caAction =
new ClassAccessPrivilegedAction ();
final FieldAccessPrivilegedAction faAction =
new FieldAccessPrivilegedAction ();
while (! queue
{
final ObjectProfileNode node = (ObjectProfileNode) queue
obj = node
final Class objClass = obj
if (objClass
{
final int arrayLength = Array
final Class componentType = objClass
// Add shell pseudo
final AbstractShellProfileNode shell =
new ArrayShellProfileNode (node
shell
node
node
if (! componentType
{
// Traverse each array slot:
for (int 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。Tw.WinGwiT.Com如前所述，它缓存了反射元数据来提高性能，并且使用了一个标识散列映射来标记访问过的对象。profile()方法从宽度优先遍历中的具有IObjectProfileNode的生成树的原始对象图形开始，以合计和分配所有节点尺寸的快速后序遍历结束。profile()返回一个 IObjectProfileNode，即产生的生成树的根，它的尺寸就是整个图形的尺寸。
当然， profile()的输出只有当我有一个很好的方法扩展它时才有用。为了这个目的，每个IObjectProfileNode 必须支持由节点访问者和节点过滤器一起进行的测试：
interface IObjectProfileNode
{
interface INodeFilter
{
boolean accept (IObjectProfileNode node);
} // End of nested interface
interface INodeVisitor
{
/**
* Pre-order visit.
*/
void previsit (IObjectProfileNode node);
/**
* Post-order visit.
*/
void postvisit (IObjectProfileNode node);
} // End of nested interface
boolean traverse (INodeFilter filter, INodeVisitor visitor);
...
} // End of interface
节点访问者只有当伴随的过滤器为null或者过滤器接收该节点时才对树节点进行操作。为了简便，节点的子节点只有当节点本身已经测试时才进行测试。前序遍历和后序遍历访问都支持。来自java.lang.Object处理程序的尺寸提供以及所有初级数据都集中放在一个伪码内，这个伪码附属于代表对象实例的每个"真实"节点。这种处理程序节点可通过IObjectProfileNode.shell()访问，也可在IObjectProfileNode.children()列表中显示出来：目的就是能够编写数据过滤器和访问者，使它们可在实例化的数据类型的同一起点上考虑初级数据。
如何实现过滤器和访问者就是你的事了。作为一个起点，类ObjectProfileFilters (见本文的download)提供几种有用的堆栈过滤器，它们可帮助你在节点尺寸、与父节点的尺寸相关的节点尺寸、与根对象相关的节点尺寸等等的基础上剪除大对象树。
ObjectProfilerVisitors类包含IObjectProfileNode.dump()使用的默认访问者，也包含能够为更高级的对象浏览创建XML转储的访问者。将配置文件转换为SwingTreeModel也是很容易的。
为了便于理解，我们创建了一个上文提及的两个字符串排列对象的完整转储：
public class Main
{
public static void main (String [] args)
{
Object obj = new String [] {new String ("JavaWorld"),
new String ("JavaWorld")};
IObjectProfileNode profile = ObjectProfiler.profile (obj);
System.out.println ("obj size = " + profile.size () + " bytes");
System.out.println (profile.dump ());
}
} // End of class
该代码结果如下：
obj size = 106 bytes
106 ->
58 (54.7%) ->
34 (32.1%) -> String#value : char[]
length= prim/ length=
prim/
实际上
简单的sizeof()
ObjectProfiler
