slf4j-api/src/main/java/org/slf4j/helpers/Util.java

/**
 * Copyright (c) 2004-2011 QOS.ch
 * All rights reserved.
 *
 * Permission is hereby granted, free  of charge, to any person obtaining
 * a  copy  of this  software  and  associated  documentation files  (the
 * "Software"), to  deal in  the Software without  restriction, including
 * without limitation  the rights to  use, copy, modify,  merge, publish,
 * distribute,  sublicense, and/or sell  copies of  the Software,  and to
 * permit persons to whom the Software  is furnished to do so, subject to
 * the following conditions:
 *
 * The  above  copyright  notice  and  this permission  notice  shall  be
 * included in all copies or substantial portions of the Software.
 *
 * THE  SOFTWARE IS  PROVIDED  "AS  IS", WITHOUT  WARRANTY  OF ANY  KIND,
 * EXPRESS OR  IMPLIED, INCLUDING  BUT NOT LIMITED  TO THE  WARRANTIES OF
 * MERCHANTABILITY,    FITNESS    FOR    A   PARTICULAR    PURPOSE    AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE,  ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 */
package org.slf4j.helpers;


/**
 *
 * An internal utility class.
 *
 * @author Ceki Gülcü
 */
public final class Util {

  private Util() {}

  /**
   * In order to call {@link SecurityManager#getClassContext()}, which is a
   * protected method, we add this wrapper which allows the method to be visible
   * inside this package.
   */
  private static final class ClassContextSecurityManager extends SecurityManager {
    protected Class<?>[] getClassContext() {
      return super.getClassContext();
    }
  };
  private static final ClassContextSecurityManager SECURITY_MANAGER =
      new ClassContextSecurityManager();

  /**
   * Returns the name of the class which called the invoking method.
   * @return the name of the class which called the invoking method.
   */
  public static Class<?> getCallingClass() {
    Class<?>[] trace = SECURITY_MANAGER.getClassContext();
    String thisClassName = Util.class.getName();

    // Advance until Util is found
    int i;
    for (i = 0 ; i < trace.length ; i++) {
      if (thisClassName.equals(trace[i].getName()))
        break;
    }

    // trace[i] = Util; trace[i+1] = caller; trace[i+2] = caller's caller
    if (i >= trace.length || i + 2 >= trace.length) {
      throw new IllegalStateException(
          "Failed to find org.slf4j.helpers.Util or its caller in the stack; " +
          "this should not happen");
    }

    return trace[i+2];
  }

  static final public void report(String msg, Throwable t) {
    System.err.println(msg);
    System.err.println("Reported exception:");
    t.printStackTrace();
  }
  
  static final public void report(String msg) {
    System.err.println("SLF4J: " +msg);
  }
}