Java tutorial
/* * Copyright (C) The MX4J Contributors. * All rights reserved. * * This software is distributed under the terms of the MX4J License version 1.0. * See the terms of the MX4J License in the documentation provided with this software. */ import java.lang.reflect.Array; import java.lang.reflect.Method; /** * Several utility functions for the JMX implementation * * @version $Revision: 1.18 $ */ public class Utils { /** * This methods load a class given the classloader and the name of the class, and work for * extended names of primitive types. <p> * If you try to do ClassLoader.loadClass("boolean") it barfs it cannot find the class, * so this method cope with this problem. */ public static Class loadClass(ClassLoader loader, String name) throws ClassNotFoundException { if (name == null) throw new ClassNotFoundException("null"); name = name.trim(); if (name.equals("boolean")) return boolean.class; else if (name.equals("byte")) return byte.class; else if (name.equals("char")) return char.class; else if (name.equals("short")) return short.class; else if (name.equals("int")) return int.class; else if (name.equals("long")) return long.class; else if (name.equals("float")) return float.class; else if (name.equals("double")) return double.class; else if (name.equals("java.lang.String")) return String.class; else if (name.equals("java.lang.Object")) return Object.class; else if (name.startsWith("[")) { // It's an array, figure out how many dimensions int dimension = 0; while (name.charAt(dimension) == '[') { ++dimension; } char type = name.charAt(dimension); Class cls = null; switch (type) { case 'Z': cls = boolean.class; break; case 'B': cls = byte.class; break; case 'C': cls = char.class; break; case 'S': cls = short.class; break; case 'I': cls = int.class; break; case 'J': cls = long.class; break; case 'F': cls = float.class; break; case 'D': cls = double.class; break; case 'L': // Strip the semicolon at the end String n = name.substring(dimension + 1, name.length() - 1); cls = loadClass(loader, n); break; } if (cls == null) { throw new ClassNotFoundException(name); } else { int[] dim = new int[dimension]; return Array.newInstance(cls, dim).getClass(); } } else { if (loader != null) return loader.loadClass(name); else return Class.forName(name, false, null); } } /** * Returns the classes whose names are specified by the <code>names</code> argument, loaded with the * specified classloader. */ public static Class[] loadClasses(ClassLoader loader, String[] names) throws ClassNotFoundException { int n = names.length; Class[] cls = new Class[n]; for (int i = 0; i < n; ++i) { String name = names[i]; cls[i] = loadClass(loader, name); } return cls; } /** * Returns true is the given method is a JMX attribute getter method */ public static boolean isAttributeGetter(Method m) { if (m == null) return false; String name = m.getName(); Class retType = m.getReturnType(); Class[] params = m.getParameterTypes(); if (retType != Void.TYPE && params.length == 0) { if (name.startsWith("get") && name.length() > 3) return true; else if (name.startsWith("is") && name.length() > 2 && retType == Boolean.TYPE) return true; } return false; } /** * Returns true if the method is a JMX attribute setter method */ public static boolean isAttributeSetter(Method m) { if (m == null) return false; String name = m.getName(); Class retType = m.getReturnType(); Class[] params = m.getParameterTypes(); if (retType == Void.TYPE && params.length == 1 && name.startsWith("set") && name.length() > 3) { return true; } return false; } public static boolean wildcardMatch(String pattern, String string) { int stringLength = string.length(); int stringIndex = 0; for (int patternIndex = 0; patternIndex < pattern.length(); ++patternIndex) { char c = pattern.charAt(patternIndex); if (c == '*') { // Recurse with the pattern without this '*' and the actual string, until // match is found or we inspected the whole string while (stringIndex < stringLength) { if (wildcardMatch(pattern.substring(patternIndex + 1), string.substring(stringIndex))) { return true; } // No match found, try a shorter string, since we are matching '*' ++stringIndex; } } else if (c == '?') { // Increment the string index, since '?' match a single char in the string ++stringIndex; if (stringIndex > stringLength) { return false; } } else { // A normal character in the pattern, must match the one in the string if (stringIndex >= stringLength || c != string.charAt(stringIndex)) { return false; } ++stringIndex; } } // I've inspected the whole pattern, but not the whole string return stringIndex == stringLength; } public static boolean arrayEquals(Object[] arr1, Object[] arr2) { if (arr1 == null && arr2 == null) return true; if (arr1 == null ^ arr2 == null) return false; if (!arr1.getClass().equals(arr2.getClass())) return false; if (arr1.length != arr2.length) return false; for (int i = 0; i < arr1.length; ++i) { Object obj1 = arr1[i]; Object obj2 = arr2[i]; if (obj1 == null ^ obj2 == null) return false; if (obj1 != null && !obj1.equals(obj2)) return false; } return true; } public static boolean arrayEquals(byte[] arr1, byte[] arr2) { if (arr1 == null && arr2 == null) return true; if (arr1 == null ^ arr2 == null) return false; if (!arr1.getClass().equals(arr2.getClass())) return false; if (arr1.length != arr2.length) return false; for (int i = 0; i < arr1.length; ++i) { byte b1 = arr1[i]; byte b2 = arr2[i]; if (b1 != b2) return false; } return true; } public static int arrayHashCode(Object[] arr) { int hash = 0; if (arr != null) { // Avoid that 2 arrays of length 0 but different classes return same hash hash ^= arr.getClass().hashCode(); for (int i = 0; i < arr.length; ++i) { hash ^= arr[i] == null ? 0 : arr[i].hashCode(); } } return hash; } public static int arrayHashCode(byte[] arr) { int hash = 0; if (arr != null) { // Avoid that 2 arrays of length 0 but different classes return same hash hash ^= arr.getClass().hashCode(); for (int i = 0; i < arr.length; ++i) { hash ^= arr[i]; } } return hash; } public static char[] arrayCopy(char[] chars) { if (chars == null) return null; char[] copy = new char[chars.length]; System.arraycopy(chars, 0, copy, 0, chars.length); return copy; } }