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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *     http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  package org.apache.commons.mail;
19  
20  import java.io.PrintStream;
21  import java.io.PrintWriter;
22  
23  /**
24   * Exception thrown when a checked error occurs in commons-email.
25   * <p>
26   * Supports nesting, emulating JDK 1.4 behavior if necessary.
27   * <p>
28   * Adapted from FunctorException in Commons Collections.
29   *
30   * @author jakarta-commons
31   * @since 1.0
32   * @version $Id: EmailException.java 510812 2007-02-23 04:32:22Z dion $
33   */
34  public class EmailException
35          extends Exception
36  {
37      /** Serializable version identifier */
38      static final long serialVersionUID = 5550674499282474616L;
39  
40      /**
41       * Does JDK support nested exceptions?
42       */
43      private static final boolean JDK_SUPPORTS_NESTED;
44  
45      static
46      {
47          boolean flag = false;
48  
49          try
50          {
51              Throwable.class.getDeclaredMethod("getCause", new Class[0]);
52              flag = true;
53          }
54          catch (NoSuchMethodException ex)
55          {
56              flag = false;
57          }
58  
59          JDK_SUPPORTS_NESTED = flag;
60      }
61  
62      /**
63       * Root cause of the exception
64       */
65      private final Throwable rootCause;
66  
67      /**
68       * Constructs a new <code>EmailException</code> with no
69       * detail message.
70       */
71      public EmailException()
72      {
73          super();
74          this.rootCause = null;
75      }
76  
77      /**
78       * Constructs a new <code>EmailException</code> with specified
79       * detail message.
80       *
81       * @param msg  the error message.
82       */
83      public EmailException(String msg)
84      {
85          super(msg);
86          this.rootCause = null;
87      }
88  
89      /**
90       * Constructs a new <code>EmailException</code> with specified
91       * nested <code>Throwable</code> root cause.
92       *
93       * @param rootCause  the exception or error that caused this exception
94       *                   to be thrown.
95       */
96      public EmailException(Throwable rootCause)
97      {
98          super((rootCause == null) ? null : rootCause.getMessage());
99          this.rootCause = rootCause;
100     }
101 
102     /**
103      * Constructs a new <code>EmailException</code> with specified
104      * detail message and nested <code>Throwable</code> root cause.
105      *
106      * @param msg  the error message.
107      * @param rootCause  the exception or error that caused this exception
108      *                   to be thrown.
109      */
110     public EmailException(String msg, Throwable rootCause)
111     {
112         super(msg);
113         this.rootCause = rootCause;
114     }
115 
116     /**
117      * Gets the cause of this throwable.
118      *
119      * @return  the cause of this throwable, or <code>null</code>
120      */
121     public Throwable getCause()
122     {
123         return rootCause;
124     }
125 
126     /**
127      * Prints the stack trace of this exception to the standard error stream.
128      */
129     public void printStackTrace()
130     {
131         printStackTrace(System.err);
132     }
133 
134     /**
135      * Prints the stack trace of this exception to the specified stream.
136      *
137      * @param out  the <code>PrintStream</code> to use for output
138      */
139     public void printStackTrace(PrintStream out)
140     {
141         synchronized (out)
142         {
143             PrintWriter pw = new PrintWriter(out, false);
144             printStackTrace(pw);
145 
146             // Flush the PrintWriter before it's GC'ed.
147             pw.flush();
148         }
149     }
150 
151     /**
152      * Prints the stack trace of this exception to the specified writer.
153      *
154      * @param out  the <code>PrintWriter</code> to use for output
155      */
156     public void printStackTrace(PrintWriter out)
157     {
158         synchronized (out)
159         {
160             super.printStackTrace(out);
161 
162             if (!JDK_SUPPORTS_NESTED && (rootCause != null))
163             {
164                 out.print("Caused by: ");
165                 rootCause.printStackTrace(out);
166             }
167         }
168     }
169 }