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