com.baidu.bjf.remoting.protobuf.utils.ClassHelper Maven / Gradle / Ivy
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/*
* Copyright (c) Baidu Inc. All rights reserved.
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.baidu.bjf.remoting.protobuf.utils;
import java.io.File;
import java.lang.reflect.Array;
import java.net.URL;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
/**
* A utility class for class and class loader.
*
* @author xiemalin
* @since 1.0.0
*/
public class ClassHelper {
/**
* package separator char
*/
public static final char PACKAGE_SEPARATOR_CHAR = '.';
/**
* package separator string
*/
public static final String PACKAGE_SEPARATOR = PACKAGE_SEPARATOR_CHAR + "";
/**
* get class internal name from Class.getName(). sub class like A$B to A.B
*
* @param clsName class name
* @return internalname
*/
public static String getInternalName(String clsName) {
if (clsName == null) {
return null;
}
return clsName;
}
public static long getLastModifyTime(Class cls) {
if (cls == null) {
return -1L;
}
String clsName = cls.getName().replace('.', '/') + ".class";
ClassLoader classLoader = cls.getClassLoader();
if (classLoader == null) {
return -1L;
}
URL resource = classLoader.getResource(clsName);
if (resource != null) {
return new File(resource.getFile()).lastModified();
}
return -1L;
}
/**
* To fix name with thread context of class loader
*
* @param name class name
* @return loaded class
* @throws ClassNotFoundException if class not found
*/
public static Class forNameWithThreadContextClassLoader(String name) throws ClassNotFoundException {
return forName(name, Thread.currentThread().getContextClassLoader());
}
/**
* to initialize clss by name from caller.
*
* @param name class name
* @param caller caller of Class type
* @return loaded class
* @throws ClassNotFoundException if class not found
*/
public static Class forNameWithCallerClassLoader(String name, Class caller) throws ClassNotFoundException {
return forName(name, caller.getClassLoader());
}
/**
* get class loader from caller calss
*
* @param caller caller of Class type
* @return loaded class loader
*/
public static ClassLoader getCallerClassLoader(Class caller) {
return caller.getClassLoader();
}
/**
* get class loader
*
* @param cls target class to get ownered class loader
* @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.
*
* 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
* Class.forName, which accepts a null ClassLoader reference as well).
*
* @return the default ClassLoader (never null)
* @see java.lang.Thread#getContextClassLoader()
*/
public static ClassLoader getClassLoader() {
return getClassLoader(ClassHelper.class);
}
/**
* Same as Class.forName(), except that it works for primitive types.
*/
public static Class forName(String name) throws ClassNotFoundException {
return forName(name, getClassLoader());
}
/**
* Replacement for Class.forName() 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 null, 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.
*
* Also supports the JVM's internal class names for primitive arrays. Does not 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 null 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) PRIMIIIVE_TYPE_NAME_MAP.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> PRIMIIIVE_TYPE_NAME_MAP = new HashMap>(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> PRIMITIVE_WRAPPER_TYPE_MAP = new HashMap, Class>(8);
static {
PRIMITIVE_WRAPPER_TYPE_MAP.put(Boolean.class, boolean.class);
PRIMITIVE_WRAPPER_TYPE_MAP.put(Byte.class, byte.class);
PRIMITIVE_WRAPPER_TYPE_MAP.put(Character.class, char.class);
PRIMITIVE_WRAPPER_TYPE_MAP.put(Double.class, double.class);
PRIMITIVE_WRAPPER_TYPE_MAP.put(Float.class, float.class);
PRIMITIVE_WRAPPER_TYPE_MAP.put(Integer.class, int.class);
PRIMITIVE_WRAPPER_TYPE_MAP.put(Long.class, long.class);
PRIMITIVE_WRAPPER_TYPE_MAP.put(Short.class, short.class);
Set> primitiveTypeNames = new HashSet>(16);
primitiveTypeNames.addAll(PRIMITIVE_WRAPPER_TYPE_MAP.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> it = primitiveTypeNames.iterator(); it.hasNext();) {
Class primitiveClass = (Class) it.next();
PRIMIIIVE_TYPE_NAME_MAP.put(primitiveClass.getName(), primitiveClass);
}
}
/**
* To get short message of object instance.
*
* @param obj target object
* @return short message
*/
public static String toShortString(Object obj) {
if (obj == null) {
return "null";
}
return obj.getClass().getSimpleName() + "@" + System.identityHashCode(obj);
}
/**
* get class simple name from {@link Class} instance.
* Here we should take case member class is a little different from common class.
*
* @param cls target class
* @return simple class name
*/
public static String getClassName(Class cls) {
if (cls.isMemberClass()) {
String name = cls.getName();
name = StringUtils.substringAfterLast(name, PACKAGE_SEPARATOR);
return name;
}
return cls.getSimpleName();
}
public static String getPackage(Class cls) {
Package pkg = cls.getPackage();
// maybe null if package is blank or dynamic load class
if (pkg == null) {
String fullName = cls.getName();
int index = fullName.lastIndexOf(PACKAGE_SEPARATOR_CHAR);
if (index != -1) {
return fullName.substring(0, index);
}
return "";
}
return pkg.getName();
}
/**
* To test class if has default constructor method
*
* @param cls target class
* @return true if has default constructor method
*/
public static boolean hasDefaultConstructor(Class cls) {
if (cls == null) {
return false;
}
try {
cls.getConstructor(new Class[0]);
} catch (NoSuchMethodException e2) {
return false;
} catch (SecurityException e2) {
throw new IllegalArgumentException(e2.getMessage(), e2);
}
return true;
}
/**
* get new class name with full package
*
* @return class name
*/
public static String getFullClassName(Class cls) {
return getPackage(cls) + PACKAGE_SEPARATOR + getClassName(cls);
}
}