递归对象写入平面csv文件

我需要写这样的东西

class User {
    UUID id;
    String name;
    Role role;
}

class Role {
    String name;
    LocalDate activeFrom;
    Authority owner;
}

class Authority {
    String name;
}

一个棘手的想法是csv编写应该通过对象树递归地工作。还需要将LocalDate写为类似2019-11-05 f.e.的字符串

生成的csv文件应该是平面的，看起来像：

user.id，user.name，user.role.name，user.role.activeFrom，user.role.owner.name

//示例值

---

我已经尝试过OpenCsv：

        StatefulBeanToCsv<User> beanToCsv = new StatefulBeanToCsvBuilder<User>(printWriter).build();
        try {
            beanToCsv.write(users);
        } catch (CsvDataTypeMismatchException | CsvRequiredFieldEmptyException e) {
            e.printStackTrace();
        }
        printWriter.close();

到目前为止运气不好。它们只能序列化为csv顶级对象。在OpenCsv中，我还遇到了序列化LocalDate的问题。

---

你能帮助我吗？建议方法或库？

由于我没有得到任何答案，我将描述我的解决方案。 我使用了图书馆：

和扩展：

代码：

以及如何测试它：

@Test
void status_written_in_csv_format() {
    // Setup
    WriteCsvToResponse objectUnderTest = new WriteCsvToResponse ();
    StringWriter stringWriter = new StringWriter();
    PrintWriter printWriter = new PrintWriter(stringWriter);

    // Given
    Status status = ...

    // When
    objectUnderTest.writeStatus(printWriter, status);

    // Then
    String actualCsv = stringWriter.toString();
    assertThat(actualCsv.split("\n"))
       .as("Produced CSV")
       .containsExactly(
         "id,storeId,status",
         "42,142,OK");
}

---

在univocity解析器上，无需任何映射，只需使用

@nested

注释嵌套对象即可

class User {
    ...

    @Nested
    Role role;
}

@Test
void status_written_in_csv_format() {
    // Setup
    WriteCsvToResponse objectUnderTest = new WriteCsvToResponse ();
    StringWriter stringWriter = new StringWriter();
    PrintWriter printWriter = new PrintWriter(stringWriter);

    // Given
    Status status = ...

    // When
    objectUnderTest.writeStatus(printWriter, status);

    // Then
    String actualCsv = stringWriter.toString();
    assertThat(actualCsv.split("\n"))
       .as("Produced CSV")
       .containsExactly(
         "id,storeId,status",
         "42,142,OK");
}

class User {
    ...

    @Nested
    Role role;
}