Java Jackson：将 csv 文件解析为包含对象列表的对象
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Java Hymanson: Parsing a csv file into an object containing a List of objects
提问by DanF7
I am trying to parse a csv file using Hymanson CsvParser into an object that also contains a list of another class.
我正在尝试使用 Hymanson CsvParser 将 csv 文件解析为一个对象，该对象还包含另一个类的列表。
So the first 2 columns contain data that needs to be bound to the parent class and the data afterwards would need to be bound to another class.
所以前两列包含需要绑定到父类的数据，之后的数据需要绑定到另一个类。
public class Person {
private String name;
private String age;
private List<CarDetails> carDetails;
//Getters+setters
}
public class CarDetails {
private String carMake;
private String carRegistration;
//Getters+setters
}
The log to be parsed would look like:
要解析的日志如下所示：
John Doe, 30, Honda, D32GHF
Or in another log of users all with 2 cars it may look like:
或者在另一个所有拥有 2 辆车的用户日志中，它可能看起来像：
Jane Doe, 29, Mini, F64RTZ, BMW, T56DFG
To parse the initial 2 items of data to the "Person" class is no problem.
将最初的 2 项数据解析到“Person”类是没有问题的。
CsvMapper mapper = new CsvMapper();
CsvSchema schema = CsvSchema.builder()
.addColumn("name")
.addColumn("age")
for(numberOfCars=2; numberOfCars!=0 ; numberOfCars--)
schema = schema.rebuild()
.addColumn("carMake")
.addColumn("carRegistration")
MappingIterator<Map.Entry> it = mapper
.reader(Person.class)
.with(schema)
.readValues(personLog);
List<Person> people = new ArrayList<Person>();
while (it.hasNextValue()) {
Person person = (Person) it.nextValue();
people.add(person);
}
But I do not know how to parse the CarDetails. It seems like I have to be able to search for the value, create a new CarDetails object and add it to the Person object, but I can't see how to extract that information.
但我不知道如何解析 CarDetails。似乎我必须能够搜索该值，创建一个新的 CarDetails 对象并将其添加到 Person 对象，但我看不到如何提取该信息。
My solution is the following:
我的解决方案如下：
List<Person> people = new ArrayList<Person>();
MappingIterator<Map<?,?>> it = mapper.reader(schema).withType(Map.class).readValues(personLog);
while(it.hasNextValue()) {
Person person = new Person();
CarDetails = new CarDetails();
Map<?,?> result = it.nextValue();
person.setName(result.get("name").toString());
carDetails.setCarMake(result.get("carMake").toString());
person.addCarDetails(carDetails);
people.add(person);
}
采纳答案by David Grant
If you look at the Javadoc for CsvMapper.readerWithSchemaFor, it states:
如果您查看CsvMapper.readerWithSchemaFor的 Javadoc ，它会指出：
no CSV types can be mapped to arrays or Collections
没有 CSV 类型可以映射到数组或集合
