001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      https://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 */
017package org.apache.commons.lang3.exception;
018
019import java.util.List;
020import java.util.Set;
021
022import org.apache.commons.lang3.tuple.Pair;
023
024/**
025 * An exception that provides an easy and safe way to add contextual information.
026 * <p>
027 * An exception trace itself is often insufficient to provide rapid diagnosis of the issue.
028 * Frequently what is needed is a select few pieces of local contextual data.
029 * Providing this data is tricky however, due to concerns over formatting and nulls.
030 * </p><p>
031 * The contexted exception approach allows the exception to be created together with a
032 * list of context label-value pairs. This additional information is automatically included in
033 * the message and printed stack trace.
034 * </p><p>
035 * An unchecked version of this exception is provided by ContextedRuntimeException.
036 * </p>
037 * <p>
038 * To use this class write code as follows:
039 * </p>
040 * <pre>
041 *   try {
042 *     ...
043 *   } catch (Exception e) {
044 *     throw new ContextedException("Error posting account transaction", e)
045 *          .addContextValue("Account Number", accountNumber)
046 *          .addContextValue("Amount Posted", amountPosted)
047 *          .addContextValue("Previous Balance", previousBalance);
048 *   }
049 * }
050 * </pre>
051 * <p>
052 * or improve diagnose data at a higher level:
053 * </p>
054 * <pre>
055 *   try {
056 *     ...
057 *   } catch (ContextedException e) {
058 *     throw e.setContextValue("Transaction Id", transactionId);
059 *   } catch (Exception e) {
060 *     if (e instanceof ExceptionContext) {
061 *       e.setContextValue("Transaction Id", transactionId);
062 *     }
063 *     throw e;
064 *   }
065 * }
066 * </pre>
067 * <p>
068 * The output in a printStacktrace() (which often is written to a log) would look something like the following:
069 * </p>
070 * <pre>
071 * org.apache.commons.lang3.exception.ContextedException: java.lang.Exception: Error posting account transaction
072 *  Exception Context:
073 *  [1:Account Number=null]
074 *  [2:Amount Posted=100.00]
075 *  [3:Previous Balance=-2.17]
076 *  [4:Transaction Id=94ef1d15-d443-46c4-822b-637f26244899]
077 *
078 *  ---------------------------------
079 *  at org.apache.commons.lang3.exception.ContextedExceptionTest.testAddValue(ContextedExceptionTest.java:88)
080 *  ..... (rest of trace)
081 * </pre>
082 *
083 * @see ContextedRuntimeException
084 * @since 3.0
085 */
086public class ContextedException extends Exception implements ExceptionContext {
087
088    /** The serialization version. */
089    private static final long serialVersionUID = 20110706L;
090
091    /** The context where the data is stored. */
092    private final ExceptionContext exceptionContext;
093
094    /**
095     * Instantiates ContextedException without message or cause.
096     * <p>
097     * The context information is stored using a default implementation.
098     */
099    public ContextedException() {
100        exceptionContext = new DefaultExceptionContext();
101    }
102
103    /**
104     * Instantiates ContextedException with message, but without cause.
105     * <p>
106     * The context information is stored using a default implementation.
107     *
108     * @param message  the exception message, may be null
109     */
110    public ContextedException(final String message) {
111        super(message);
112        exceptionContext = new DefaultExceptionContext();
113    }
114
115    /**
116     * Instantiates ContextedException with cause and message.
117     * <p>
118     * The context information is stored using a default implementation.
119     *
120     * @param message  the exception message, may be null
121     * @param cause  the underlying cause of the exception, may be null
122     */
123    public ContextedException(final String message, final Throwable cause) {
124        super(message, cause);
125        exceptionContext = new DefaultExceptionContext();
126    }
127
128    /**
129     * Instantiates ContextedException with cause, message, and ExceptionContext.
130     *
131     * @param message  the exception message, may be null
132     * @param cause  the underlying cause of the exception, may be null
133     * @param context  the context used to store the additional information, null uses default implementation
134     */
135    public ContextedException(final String message, final Throwable cause, ExceptionContext context) {
136        super(message, cause);
137        if (context == null) {
138            context = new DefaultExceptionContext();
139        }
140        exceptionContext = context;
141    }
142
143    /**
144     * Instantiates ContextedException with cause, but without message.
145     * <p>
146     * The context information is stored using a default implementation.
147     *
148     * @param cause  the underlying cause of the exception, may be null
149     */
150    public ContextedException(final Throwable cause) {
151        super(cause);
152        exceptionContext = new DefaultExceptionContext();
153    }
154
155    /**
156     * Adds information helpful to a developer in diagnosing and correcting the problem.
157     * For the information to be meaningful, the value passed should have a reasonable
158     * toString() implementation.
159     * Different values can be added with the same label multiple times.
160     * <p>
161     * Note: This exception is only serializable if the object added is serializable.
162     * </p>
163     *
164     * @param label  a textual label associated with information, {@code null} not recommended
165     * @param value  information needed to understand exception, may be {@code null}
166     * @return {@code this}, for method chaining, not {@code null}
167     */
168    @Override
169    public ContextedException addContextValue(final String label, final Object value) {
170        exceptionContext.addContextValue(label, value);
171        return this;
172    }
173
174    /**
175     * {@inheritDoc}
176     */
177    @Override
178    public List<Pair<String, Object>> getContextEntries() {
179        return this.exceptionContext.getContextEntries();
180    }
181
182    /**
183     * {@inheritDoc}
184     */
185    @Override
186    public Set<String> getContextLabels() {
187        return exceptionContext.getContextLabels();
188    }
189
190    /**
191     * {@inheritDoc}
192     */
193    @Override
194    public List<Object> getContextValues(final String label) {
195        return this.exceptionContext.getContextValues(label);
196    }
197
198    /**
199     * {@inheritDoc}
200     */
201    @Override
202    public Object getFirstContextValue(final String label) {
203        return this.exceptionContext.getFirstContextValue(label);
204    }
205
206    /**
207     * {@inheritDoc}
208     */
209    @Override
210    public String getFormattedExceptionMessage(final String baseMessage) {
211        return exceptionContext.getFormattedExceptionMessage(baseMessage);
212    }
213
214    /**
215     * Provides the message explaining the exception, including the contextual data.
216     *
217     * @see Throwable#getMessage()
218     * @return the message, never null
219     */
220    @Override
221    public String getMessage() {
222        return getFormattedExceptionMessage(super.getMessage());
223    }
224
225    /**
226     * Provides the message explaining the exception without the contextual data.
227     *
228     * @see Throwable#getMessage()
229     * @return the message
230     * @since 3.0.1
231     */
232    public String getRawMessage() {
233        return super.getMessage();
234    }
235
236    /**
237     * Sets information helpful to a developer in diagnosing and correcting the problem.
238     * For the information to be meaningful, the value passed should have a reasonable
239     * toString() implementation.
240     * Any existing values with the same labels are removed before the new one is added.
241     * <p>
242     * Note: This exception is only serializable if the object added as value is serializable.
243     * </p>
244     *
245     * @param label  a textual label associated with information, {@code null} not recommended
246     * @param value  information needed to understand exception, may be {@code null}
247     * @return {@code this}, for method chaining, not {@code null}
248     */
249    @Override
250    public ContextedException setContextValue(final String label, final Object value) {
251        exceptionContext.setContextValue(label, value);
252        return this;
253    }
254}