package com.taobao.tddl.common.utils;
import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
public class ClassHelper {
public static Class<?> forNameWithThreadContextClassLoader(String name) throws ClassNotFoundException {
return forName(name, Thread.currentThread().getContextClassLoader());
}
public static Class<?> forNameWithCallerClassLoader(String name, Class<?> caller) throws ClassNotFoundException {
return forName(name, caller.getClassLoader());
}
public static ClassLoader getCallerClassLoader(Class<?> caller) {
return caller.getClassLoader();
}
/**
* get class loader
*
* @param cls
* @return class loader
*/
public static ClassLoader getClassLoader(Class<?> cls) {
ClassLoader cl = null;
try {
cl = Thread.currentThread().getContextClassLoader();
} catch (Throwable ex) {
// Cannot access thread context ClassLoader - falling back to system
// class loader...
}
if (cl == null) {
// No thread context class loader -> use class loader of this class.
cl = cls.getClassLoader();
}
return cl;
}
/**
* Return the default ClassLoader to use: typically the thread context
* ClassLoader, if available; the ClassLoader that loaded the ClassUtils
* class will be used as fallback.
* <p>
* Call this method if you intend to use the thread context ClassLoader in a
* scenario where you absolutely need a non-null ClassLoader reference: for
* example, for class path resource loading (but not necessarily for
* <code>Class.forName</code>, which accepts a <code>null</code> ClassLoader
* reference as well).
*
* @return the default ClassLoader (never <code>null</code>)
* @see java.lang.Thread#getContextClassLoader()
*/
public static ClassLoader getClassLoader() {
return getClassLoader(ClassHelper.class);
}
/**
* Same as <code>Class.forName()</code>, except that it works for primitive
* types.
*/
public static Class<?> forName(String name) throws ClassNotFoundException {
return forName(name, getClassLoader());
}
/**
* Replacement for <code>Class.forName()</code> that also returns Class
* instances for primitives (like "int") and array class names (like
* "String[]").
*
* @param name the name of the Class
* @param classLoader the class loader to use (may be <code>null</code>,
* which indicates the default class loader)
* @return Class instance for the supplied name
* @throws ClassNotFoundException if the class was not found
* @throws LinkageError if the class file could not be loaded
* @see Class#forName(String, boolean, ClassLoader)
*/
public static Class<?> forName(String name, ClassLoader classLoader) throws ClassNotFoundException, LinkageError {
Class<?> clazz = resolvePrimitiveClassName(name);
if (clazz != null) {
return clazz;
}
// "java.lang.String[]" style arrays
if (name.endsWith(ARRAY_SUFFIX)) {
String elementClassName = name.substring(0, name.length() - ARRAY_SUFFIX.length());
Class<?> elementClass = forName(elementClassName, classLoader);
return Array.newInstance(elementClass, 0).getClass();
}
// "[Ljava.lang.String;" style arrays
int internalArrayMarker = name.indexOf(INTERNAL_ARRAY_PREFIX);
if (internalArrayMarker != -1 && name.endsWith(";")) {
String elementClassName = null;
if (internalArrayMarker == 0) {
elementClassName = name.substring(INTERNAL_ARRAY_PREFIX.length(), name.length() - 1);
} else if (name.startsWith("[")) {
elementClassName = name.substring(1);
}
Class<?> elementClass = forName(elementClassName, classLoader);
return Array.newInstance(elementClass, 0).getClass();
}
ClassLoader classLoaderToUse = classLoader;
if (classLoaderToUse == null) {
classLoaderToUse = getClassLoader();
}
return classLoaderToUse.loadClass(name);
}
/**
* Resolve the given class name as primitive class, if appropriate,
* according to the JVM's naming rules for primitive classes.
* <p>
* Also supports the JVM's internal class names for primitive arrays. Does
* <i>not</i> support the "[]" suffix notation for primitive arrays; this is
* only supported by {@link #forName}.
*
* @param name the name of the potentially primitive class
* @return the primitive class, or <code>null</code> if the name does not
* denote a primitive class or primitive array class
*/
public static Class<?> resolvePrimitiveClassName(String name) {
Class<?> result = null;
// Most class names will be quite long, considering that they
// SHOULD sit in a package, so a length check is worthwhile.
if (name != null && name.length() <= 8) {
// Could be a primitive - likely.
result = (Class<?>) primitiveTypeNameMap.get(name);
}
return result;
}
/** Suffix for array class names: "[]" */
public static final String ARRAY_SUFFIX = "[]";
/** Prefix for internal array class names: "[L" */
private static final String INTERNAL_ARRAY_PREFIX = "[L";
/**
* Map with primitive type name as key and corresponding primitive type as
* value, for example: "int" -> "int.class".
*/
private static final Map<String, Class<?>> primitiveTypeNameMap = new HashMap<String, Class<?>>(16);
/**
* Map with primitive wrapper type as key and corresponding primitive type
* as value, for example: Integer.class -> int.class.
*/
private static final Map<Class<?>, Class<?>> primitiveWrapperTypeMap = new HashMap<Class<?>, Class<?>>(8);
static {
primitiveWrapperTypeMap.put(Boolean.class, boolean.class);
primitiveWrapperTypeMap.put(Byte.class, byte.class);
primitiveWrapperTypeMap.put(Character.class, char.class);
primitiveWrapperTypeMap.put(Double.class, double.class);
primitiveWrapperTypeMap.put(Float.class, float.class);
primitiveWrapperTypeMap.put(Integer.class, int.class);
primitiveWrapperTypeMap.put(Long.class, long.class);
primitiveWrapperTypeMap.put(Short.class, short.class);
Set<Class<?>> primitiveTypeNames = new HashSet<Class<?>>(16);
primitiveTypeNames.addAll(primitiveWrapperTypeMap.values());
primitiveTypeNames.addAll(Arrays.asList(new Class<?>[] { boolean[].class, byte[].class, char[].class,
double[].class, float[].class, int[].class, long[].class, short[].class }));
for (Iterator<Class<?>> it = primitiveTypeNames.iterator(); it.hasNext();) {
Class<?> primitiveClass = (Class<?>) it.next();
primitiveTypeNameMap.put(primitiveClass.getName(), primitiveClass);
}
}
public static String toShortString(Object obj) {
if (obj == null) {
return "null";
}
return obj.getClass().getSimpleName() + "@" + System.identityHashCode(obj);
}
}