1 /**
2 * Copyright (c) 2004-2011 QOS.ch
3 * All rights reserved.
4 *
5 * Permission is hereby granted, free of charge, to any person obtaining
6 * a copy of this software and associated documentation files (the
7 * "Software"), to deal in the Software without restriction, including
8 * without limitation the rights to use, copy, modify, merge, publish,
9 * distribute, sublicense, and/or sell copies of the Software, and to
10 * permit persons to whom the Software is furnished to do so, subject to
11 * the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be
14 * included in all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
19 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
20 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
21 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
22 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23 *
24 */
25 package org.slf4j.helpers;
26
27 /**
28 * An internal utility class.
29 *
30 * @author Alexander Dorokhine
31 * @author Ceki Gülcü
32 */
33 public final class Util {
34
35
36 private Util() {
37 }
38
39 public static String safeGetSystemProperty(String key) {
40 if (key == null)
41 throw new IllegalArgumentException("null input");
42
43 String result = null;
44 try {
45 result = System.getProperty(key);
46 } catch (java.lang.SecurityException sm) {
47 ; // ignore
48 }
49 return result;
50 }
51
52 public static boolean safeGetBooleanSystemProperty(String key) {
53 String value = safeGetSystemProperty(key);
54 if (value == null)
55 return false;
56 else
57 return value.equalsIgnoreCase("true");
58 }
59
60 /**
61 * In order to call {@link SecurityManager#getClassContext()}, which is a
62 * protected method, we add this wrapper which allows the method to be visible
63 * inside this package.
64 */
65 private static final class ClassContextSecurityManager extends SecurityManager {
66 protected Class<?>[] getClassContext() {
67 return super.getClassContext();
68 }
69 }
70
71 private static ClassContextSecurityManager SECURITY_MANAGER;
72 private static boolean SECURITY_MANAGER_CREATION_ALREADY_ATTEMPTED = false;
73
74 private static ClassContextSecurityManager getSecurityManager() {
75 if (SECURITY_MANAGER != null)
76 return SECURITY_MANAGER;
77 else if (SECURITY_MANAGER_CREATION_ALREADY_ATTEMPTED)
78 return null;
79 else {
80 SECURITY_MANAGER = safeCreateSecurityManager();
81 SECURITY_MANAGER_CREATION_ALREADY_ATTEMPTED = true;
82 return SECURITY_MANAGER;
83 }
84 }
85
86 private static ClassContextSecurityManager safeCreateSecurityManager() {
87 try {
88 return new ClassContextSecurityManager();
89 } catch (java.lang.SecurityException sm) {
90 return null;
91 }
92 }
93
94 /**
95 * Returns the name of the class which called the invoking method.
96 *
97 * @return the name of the class which called the invoking method.
98 */
99 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 }