代码引用自：https://blog.csdn.net/antony9118/article/details/54317637 感谢博主分享：
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List; /**
* This class contains object info generated by ClassIntrospector tool
*/
public class ObjectInfo {
/** Field name */
public final String name;
/** Field type name */
public final String type;
/** Field data formatted as string */
public final String contents;
/** Field offset from the start of parent object */
public final int offset;
/** Memory occupied by this field */
public final int length;
/** Offset of the first cell in the array */
public final int arrayBase;
/** Size of a cell in the array */
public final int arrayElementSize;
/** Memory occupied by underlying array (shallow), if this is array type */
public final int arraySize;
/** This object fields */
public final List<ObjectInfo> children; public ObjectInfo(String name, String type, String contents, int offset, int length, int arraySize,
int arrayBase, int arrayElementSize) {
this.name = name;
this.type = type;
this.contents = contents;
this.offset = offset;
this.length = length;
this.arraySize = arraySize;
this.arrayBase = arrayBase;
this.arrayElementSize = arrayElementSize;
children = new ArrayList<ObjectInfo>(1);
} public void addChild(final ObjectInfo info) {
if (info != null) {
children.add(info);
}
} /**
* Get the full amount of memory occupied by a given object. This value may be slightly less than
* an actual value because we don't worry about memory alignment - possible padding after the last object field.
*
* The result is equal to the last field offset + last field length + all array sizes + all child objects deep sizes
*
* @return Deep object size
*/
public long getDeepSize() {
//return length + arraySize + getUnderlyingSize( arraySize != 0 );
return addPaddingSize(arraySize + getUnderlyingSize(arraySize != 0));
} long size = 0; private long getUnderlyingSize(final boolean isArray) {
//long size = 0;
for (final ObjectInfo child : children)
size += child.arraySize + child.getUnderlyingSize(child.arraySize != 0);
if (!isArray && !children.isEmpty()) {
int tempSize = children.get(children.size() - 1).offset + children.get(children.size() - 1).length;
size += addPaddingSize(tempSize);
} return size;
} private static final class OffsetComparator implements Comparator<ObjectInfo> {
@Override
public int compare(final ObjectInfo o1, final ObjectInfo o2) {
return o1.offset - o2.offset; //safe because offsets are small non-negative numbers
}
} //sort all children by their offset
public void sort() {
Collections.sort(children, new OffsetComparator());
} @Override
public String toString() {
final StringBuilder sb = new StringBuilder();
toStringHelper(sb, 0);
return sb.toString();
} private void toStringHelper(final StringBuilder sb, final int depth) {
depth(sb, depth).append("name=").append(name).append(", type=").append(type)
.append(", contents=").append(contents).append(", offset=").append(offset)
.append(", length=").append(length);
if (arraySize > 0) {
sb.append(", arrayBase=").append(arrayBase);
sb.append(", arrayElemSize=").append(arrayElementSize);
sb.append(", arraySize=").append(arraySize);
}
for (final ObjectInfo child : children) {
sb.append('\n');
child.toStringHelper(sb, depth + 1);
}
} private StringBuilder depth(final StringBuilder sb, final int depth) {
for (int i = 0; i < depth; ++i)
sb.append("\t");
return sb;
} private long addPaddingSize(long size) {
if (size % 8 != 0) {
return (size / 8 + 1) * 8;
}
return size;
} }
ObjectInfo
import java.lang.reflect.Array;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.IdentityHashMap;
import java.util.List;
import java.util.Map; import sun.misc.Unsafe; /**
* This class could be used for any object contents/memory layout printing.
*/
public class ClassIntrospector { private static final Unsafe unsafe;
/** Size of any Object reference */
private static final int objectRefSize;
static {
try {
Field field = Unsafe.class.getDeclaredField("theUnsafe");
field.setAccessible(true);
unsafe = (Unsafe) field.get(null); objectRefSize = unsafe.arrayIndexScale(Object[].class);
} catch (Exception e) {
throw new RuntimeException(e);
}
} /** Sizes of all primitive values */
private static final Map<Class, Integer> primitiveSizes; static {
primitiveSizes = new HashMap<Class, Integer>(10);
primitiveSizes.put(byte.class, 1);
primitiveSizes.put(char.class, 2);
primitiveSizes.put(int.class, 4);
primitiveSizes.put(long.class, 8);
primitiveSizes.put(float.class, 4);
primitiveSizes.put(double.class, 8);
primitiveSizes.put(boolean.class, 1);
} /**
* Get object information for any Java object. Do not pass primitives to
* this method because they will boxed and the information you will get will
* be related to a boxed version of your value.
*
* @param obj
* Object to introspect
* @return Object info
* @throws IllegalAccessException
*/
public ObjectInfo introspect(final Object obj)
throws IllegalAccessException {
try {
return introspect(obj, null);
} finally { // clean visited cache before returning in order to make
// this object reusable
m_visited.clear();
}
} // we need to keep track of already visited objects in order to support
// cycles in the object graphs
private IdentityHashMap<Object, Boolean> m_visited = new IdentityHashMap<Object, Boolean>(
100); private ObjectInfo introspect(final Object obj, final Field fld)
throws IllegalAccessException {
// use Field type only if the field contains null. In this case we will
// at least know what's expected to be
// stored in this field. Otherwise, if a field has interface type, we
// won't see what's really stored in it.
// Besides, we should be careful about primitives, because they are
// passed as boxed values in this method
// (first arg is object) - for them we should still rely on the field
// type.
boolean isPrimitive = fld != null && fld.getType().isPrimitive();
boolean isRecursive = false; // will be set to true if we have already
// seen this object
if (!isPrimitive) {
if (m_visited.containsKey(obj)) {
isRecursive = true;
}
m_visited.put(obj, true);
} final Class type = (fld == null || (obj != null && !isPrimitive)) ? obj
.getClass() : fld.getType();
int arraySize = 0;
int baseOffset = 0;
int indexScale = 0;
if (type.isArray() && obj != null) {
baseOffset = unsafe.arrayBaseOffset(type);
indexScale = unsafe.arrayIndexScale(type);
arraySize = baseOffset + indexScale * Array.getLength(obj);
} final ObjectInfo root;
if (fld == null) {
root = new ObjectInfo("", type.getCanonicalName(), getContents(obj,
type), 0, getShallowSize(type), arraySize, baseOffset,
indexScale);
} else {
final int offset = (int) unsafe.objectFieldOffset(fld);
root = new ObjectInfo(fld.getName(), type.getCanonicalName(),
getContents(obj, type), offset, getShallowSize(type),
arraySize, baseOffset, indexScale);
} if (!isRecursive && obj != null) {
if (isObjectArray(type)) {
// introspect object arrays
final Object[] ar = (Object[]) obj;
for (final Object item : ar)
if (item != null) {
root.addChild(introspect(item, null));
}
} else {
for (final Field field : getAllFields(type)) {
if ((field.getModifiers() & Modifier.STATIC) != 0) {
continue;
}
field.setAccessible(true);
root.addChild(introspect(field.get(obj), field));
}
}
} root.sort(); // sort by offset
return root;
} // get all fields for this class, including all superclasses fields
private static List<Field> getAllFields(final Class type) {
if (type.isPrimitive()) {
return Collections.emptyList();
}
Class cur = type;
final List<Field> res = new ArrayList<Field>(10);
while (true) {
Collections.addAll(res, cur.getDeclaredFields());
if (cur == Object.class) {
break;
}
cur = cur.getSuperclass();
}
return res;
} // check if it is an array of objects. I suspect there must be a more
// API-friendly way to make this check.
private static boolean isObjectArray(final Class type) {
if (!type.isArray()) {
return false;
}
if (type == byte[].class || type == boolean[].class
|| type == char[].class || type == short[].class
|| type == int[].class || type == long[].class
|| type == float[].class || type == double[].class) {
return false;
}
return true;
} // advanced toString logic
private static String getContents(final Object val, final Class type) {
if (val == null) {
return "null";
}
if (type.isArray()) {
if (type == byte[].class) {
return Arrays.toString((byte[]) val);
} else if (type == boolean[].class) {
return Arrays.toString((boolean[]) val);
} else if (type == char[].class) {
return Arrays.toString((char[]) val);
} else if (type == short[].class) {
return Arrays.toString((short[]) val);
} else if (type == int[].class) {
return Arrays.toString((int[]) val);
} else if (type == long[].class) {
return Arrays.toString((long[]) val);
} else if (type == float[].class) {
return Arrays.toString((float[]) val);
} else if (type == double[].class) {
return Arrays.toString((double[]) val);
} else {
return Arrays.toString((Object[]) val);
}
}
return val.toString();
} // obtain a shallow size of a field of given class (primitive or object
// reference size)
private static int getShallowSize(final Class type) {
if (type.isPrimitive()) {
final Integer res = primitiveSizes.get(type);
return res != null ? res : 0;
} else {
return objectRefSize;
}
}
}
ClassIntrospector
使用：
final ClassIntrospector ci = new ClassIntrospector();
ObjectInfo res;
System.out.println("int:" + ci.introspect(new Integer(2)).getDeepSize());
System.out.println("str3:" + ci.introspect("abcd").getDeepSize()); res = ci.introspect(new ObjectA());
System.out.println("ObjectA:" + res.getDeepSize());
其中 ObjectA：
private static class ObjectA {
String str; //
int i1; //
byte b1; //
byte b2; //
int i2; //
byte b3; //
ObjectB obj; //
}
private static class ObjectB {
}