001/** 002 * Copyright (c) 2004-2011 QOS.ch 003 * All rights reserved. 004 * 005 * Permission is hereby granted, free of charge, to any person obtaining 006 * a copy of this software and associated documentation files (the 007 * "Software"), to deal in the Software without restriction, including 008 * without limitation the rights to use, copy, modify, merge, publish, 009 * distribute, sublicense, and/or sell copies of the Software, and to 010 * permit persons to whom the Software is furnished to do so, subject to 011 * the following conditions: 012 * 013 * The above copyright notice and this permission notice shall be 014 * included in all copies or substantial portions of the Software. 015 * 016 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 017 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 018 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 019 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE 020 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 021 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 022 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 023 * 024 */ 025package org.slf4j.helpers; 026 027/** 028 * An internal utility class. 029 * 030 * @author Alexander Dorokhine 031 * @author Ceki Gülcü 032 */ 033public final class Util { 034 035 036 private Util() { 037 } 038 039 public static String safeGetSystemProperty(String key) { 040 if (key == null) 041 throw new IllegalArgumentException("null input"); 042 043 String result = null; 044 try { 045 result = System.getProperty(key); 046 } catch (java.lang.SecurityException sm) { 047 ; // ignore 048 } 049 return result; 050 } 051 052 public static boolean safeGetBooleanSystemProperty(String key) { 053 String value = safeGetSystemProperty(key); 054 if (value == null) 055 return false; 056 else 057 return value.equalsIgnoreCase("true"); 058 } 059 060 /** 061 * In order to call {@link SecurityManager#getClassContext()}, which is a 062 * protected method, we add this wrapper which allows the method to be visible 063 * inside this package. 064 */ 065 private static final class ClassContextSecurityManager extends SecurityManager { 066 protected Class<?>[] getClassContext() { 067 return super.getClassContext(); 068 } 069 } 070 071 private static ClassContextSecurityManager SECURITY_MANAGER; 072 private static boolean SECURITY_MANAGER_CREATION_ALREADY_ATTEMPTED = false; 073 074 private static ClassContextSecurityManager getSecurityManager() { 075 if (SECURITY_MANAGER != null) 076 return SECURITY_MANAGER; 077 else if (SECURITY_MANAGER_CREATION_ALREADY_ATTEMPTED) 078 return null; 079 else { 080 SECURITY_MANAGER = safeCreateSecurityManager(); 081 SECURITY_MANAGER_CREATION_ALREADY_ATTEMPTED = true; 082 return SECURITY_MANAGER; 083 } 084 } 085 086 private static ClassContextSecurityManager safeCreateSecurityManager() { 087 try { 088 return new ClassContextSecurityManager(); 089 } catch (java.lang.SecurityException sm) { 090 return null; 091 } 092 } 093 094 /** 095 * Returns the name of the class which called the invoking method. 096 * 097 * @return the name of the class which called the invoking method. 098 */ 099 public static Class<?> getCallingClass() { 100 ClassContextSecurityManager securityManager = getSecurityManager(); 101 if (securityManager == null) 102 return null; 103 Class<?>[] trace = securityManager.getClassContext(); 104 String thisClassName = Util.class.getName(); 105 106 // Advance until Util is found 107 int i; 108 for (i = 0; i < trace.length; i++) { 109 if (thisClassName.equals(trace[i].getName())) 110 break; 111 } 112 113 // trace[i] = Util; trace[i+1] = caller; trace[i+2] = caller's caller 114 if (i >= trace.length || i + 2 >= trace.length) { 115 throw new IllegalStateException("Failed to find org.slf4j.helpers.Util or its caller in the stack; " + "this should not happen"); 116 } 117 118 return trace[i + 2]; 119 } 120 121 static final public void report(String msg, Throwable t) { 122 System.err.println(msg); 123 System.err.println("Reported exception:"); 124 t.printStackTrace(); 125 } 126 127 static final public void report(String msg) { 128 System.err.println("SLF4J: " + msg); 129 } 130 131 132 133}