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| 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.Comparator;
import java.util.HashMap;
import java.util.IdentityHashMap;
import java.util.List;
import java.util.Map;
import sun.misc.Unsafe;
/**
* 实现计算对象大小的类
*/
public class ClassIntrospector {
private static final Unsafe unsafe;
/**
* 引用大小
*/
private static final int objectRefSize;
public static int getObjectRefSize() {
return objectRefSize;
}
/**
* 获取unsafe对象
*/
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<>(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);
}
public ObjectInfo introspect(final Object obj) throws IllegalAccessException {
try {
return introspect(obj, null);
} finally {
// 获得对象大小后，清空缓存，以便对象重用
visited.clear();
}
}
private IdentityHashMap<Object, Boolean> visited = new IdentityHashMap<>(100);
private ObjectInfo introspect(final Object obj, final Field fld) throws IllegalAccessException {
boolean isPrimitive = fld != null && fld.getType().isPrimitive();
// will be set to true if we have already
boolean isRecursive = false;
// seen this object
if (!isPrimitive) {
if (visited.containsKey(obj)) {
isRecursive = true;
}
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));
}
}
}
// sort by offset
root.sort();
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;
}
return type != byte[].class && type != boolean[].class
&& type != char[].class && type != short[].class
&& type != int[].class && type != long[].class
&& type != float[].class && type != double[].class;
}
private static String getContents(final Object val, final Class type) {
//advanced toString logic
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;
}
}
public static class ObjectInfo {
public final String name;
public final String type;
public final String contents;
public final int offset;
public final int length;
public final int arrayBase;
public final int arrayElementSize;
public final int arraySize;
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);
}
}
public long getDeepSize() {
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) {
//safe because offsets are small non-negative numbers
return o1.offset - o2.offset;
}
}
public void sort() {
//sort all children by their offset
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;
}
}
}
|
