Jackson CsvMapper 将对象与地图映射到 csv

Question

我有一个复杂的 java 对象，我想使用 Jacksons CsvMapper 将其映射到 csv。

public class TestObject {
  private Map<String, Map<String, String>> values;
  @JsonAnyGetter
  public Map<String, Map<String, String>> getValues() {
      return values;
  }

  @JsonAnySetter
  public void setValues(Map<String, Map<String, String>> values) {
    this.values = values;
  }

}

该对象是 TestObjects 列表：

 CsvMapper mapper = new CsvMapper(); 
 CsvSchema schema = mapper.schemaFor(clazz).withUseHeader(true);
 
 ObjectWriter myObjectWriter = mapper.writer(schema);
 return myObjectWriter.writeValueAsString(objectList);

但是，当我尝试将其映射到 csv 时，由于地图中的值（因为它是地图的地图），我收到错误。

Caused by: com.fasterxml.jackson.dataformat.csv.CsvMappingException: Unrecognized column 'test_column': known columns: ....

有谁知道如何让 jacksons csvmapper 正确地将这张地图转换为 csv？

Answer 1

这可能会解决你的问题。完整示例此处

/**
 * @param listOfMap
 * @param writer
 * @throws IOException
 */
public static void csvWriter(List<HashMap<String, String>> listOfMap, Writer writer) throws IOException {
    CsvSchema schema = null;
    CsvSchema.Builder schemaBuilder = CsvSchema.builder();
    if (listOfMap != null && !listOfMap.isEmpty()) {
        for (String col : listOfMap.get(0).keySet()) {
            schemaBuilder.addColumn(col);
        }
        schema = schemaBuilder.build().withLineSeparator(System.lineSeparator()).withHeader();
    }
    CsvMapper mapper = new CsvMapper();
    mapper.writer(schema).writeValues(writer).writeAll(listOfMap);
    writer.flush();
}