001package runwar.util;
002/*
003 * Copyright 2002-2005 the original author or authors.
004 * 
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 * 
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 * 
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018
019/**
020 * Utility class for diagnostic purposes, to analyze the
021 * ClassLoader hierarchy for any given object or class loader.
022 *
023 * @author Rod Johnson
024 * @author Juergen Hoeller
025 * @since 02 April 2001
026 * @see java.lang.ClassLoader
027 */
028public abstract class ClassLoaderUtils {
029
030  /**
031   * Show the class loader hierarchy for this class.
032   * Uses default line break and tab text characters.
033   * @param obj object to analyze loader hierarchy for
034   * @param role a description of the role of this class in the application
035   * (e.g., "servlet" or "EJB reference")
036   * @return a String showing the class loader hierarchy for this class
037   */
038  public static String showClassLoaderHierarchy(Object obj, String role) {
039    return showClassLoaderHierarchy(obj, role, "\n", "\t");
040  }
041
042  /**
043   * Show the class loader hierarchy for this class.
044   * @param obj object to analyze loader hierarchy for
045   * @param role a description of the role of this class in the application
046   * (e.g., "servlet" or "EJB reference")
047   * @param lineBreak line break
048   * @param tabText text to use to set tabs
049   * @return a String showing the class loader hierarchy for this class
050   */
051  public static String showClassLoaderHierarchy(Object obj, String role, String lineBreak, String tabText) {
052    String s = "object of " + obj.getClass() + ": role is " + role + lineBreak;
053    return s + showClassLoaderHierarchy(obj.getClass().getClassLoader(), lineBreak, tabText, 0);
054  }
055
056  /**
057   * Show the class loader hierarchy for the given class loader.
058   * Uses default line break and tab text characters.
059   * @param cl class loader to analyze hierarchy for
060   * @return a String showing the class loader hierarchy for this class
061   */
062  public static String showClassLoaderHierarchy(ClassLoader cl) {
063    return showClassLoaderHierarchy(cl, "\n", "\t");
064  }
065
066  /**
067   * Show the class loader hierarchy for the given class loader.
068   * @param cl class loader to analyze hierarchy for
069   * @param lineBreak line break
070   * @param tabText text to use to set tabs
071   * @return a String showing the class loader hierarchy for this class
072   */
073  public static String showClassLoaderHierarchy(ClassLoader cl, String lineBreak, String tabText) {
074    return showClassLoaderHierarchy(cl, lineBreak, tabText, 0);
075  }
076
077  /**
078   * Show the class loader hierarchy for the given class loader.
079   * @param cl class loader to analyze hierarchy for
080   * @param lineBreak line break
081   * @param tabText text to use to set tabs
082   * @param indent nesting level (from 0) of this loader; used in pretty printing
083   * @return a String showing the class loader hierarchy for this class
084   */
085  private static String showClassLoaderHierarchy(ClassLoader cl, String lineBreak, String tabText, int indent) {
086    if (cl == null) {
087      ClassLoader ccl = Thread.currentThread().getContextClassLoader();
088      return "context class loader=[" + ccl + "] hashCode=" + ccl.hashCode();
089    }
090    StringBuffer buf = new StringBuffer();
091    for (int i = 0; i < indent; i++) {
092      buf.append(tabText);
093    }
094    buf.append("[").append(cl).append("] hashCode=").append(cl.hashCode()).append(lineBreak);
095    ClassLoader parent = cl.getParent();
096    return buf.toString() + showClassLoaderHierarchy(parent, lineBreak, tabText, indent + 1);
097  }
098
099}