View Javadoc

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  package org.apache.logging.log4j.core.appender.db.jpa.converter;
18  
19  import java.io.IOException;
20  import java.util.List;
21  
22  import javax.persistence.AttributeConverter;
23  import javax.persistence.PersistenceException;
24  
25  import org.apache.logging.log4j.ThreadContext;
26  import org.apache.logging.log4j.spi.DefaultThreadContextStack;
27  
28  import com.fasterxml.jackson.core.type.TypeReference;
29  
30  /**
31   * A JPA 2.1 attribute converter for {@link ThreadContext.ContextStack}s in
32   * {@link org.apache.logging.log4j.core.LogEvent}s. This converter is capable of converting both to and from
33   * {@link String}s.
34   *
35   * In addition to other optional dependencies required by the JPA appender, this converter requires the Jackson Data
36   * Processor.
37   */
38  public class ContextStackJsonAttributeConverter implements AttributeConverter<ThreadContext.ContextStack, String> {
39      @Override
40      public String convertToDatabaseColumn(final ThreadContext.ContextStack contextStack) {
41          try {
42              return ContextMapJsonAttributeConverter.OBJECT_MAPPER.writeValueAsString(contextStack.asList());
43          } catch (IOException e) {
44              throw new PersistenceException("Failed to convert stack list to JSON string.", e);
45          }
46      }
47  
48      @Override
49      public ThreadContext.ContextStack convertToEntityAttribute(final String s) {
50          if (s == null || s.length() == 0) {
51              return null;
52          }
53  
54          List<String> list;
55          try {
56              list = ContextMapJsonAttributeConverter.OBJECT_MAPPER.readValue(s, new TypeReference<List<String>>() { });
57          } catch (IOException e) {
58              throw new PersistenceException("Failed to convert JSON string to list for stack.", e);
59          }
60  
61          DefaultThreadContextStack result = new DefaultThreadContextStack(true);
62          result.addAll(list);
63          return result;
64      }
65  }