测试我的JSON文件并在java中获得“UnrecognizedPropertyException”错误

Question

我在测试类中读取我的JSON文件时遇到此错误，看它是否有效，我不明白为什么。它已经过验证，因此JSON文件没有任何问题。任何帮助将不胜感激。

我的考试班：

public class ObjectToJsonFile {
    public static void main(String[] args) {
    ObjectMapper mapper = new ObjectMapper();
    File file = new File("question.json");

    try {
        // Deserialize JSON file into Java object.
        Question question= mapper.readValue(file, Question.class);
        System.out.println("category.getCategory() = " + question.getCategory());
    } catch (IOException e) {
        e.printStackTrace();
    }
}

我的答案类看起来像这样：

public class Answer  
 {

@JsonProperty("answer")
private String answer;
@JsonProperty("correct")
private Boolean correct;
//setters and getters
}

我的问题类看起来像这样：public class Question {

@JsonProperty("category")
private String category;
@JsonProperty("clue")
private String clue;
@JsonProperty("Answers")
private List<Answer> answers;
@JsonProperty("questionTitle")
private String questionTitle;
//setters an getters
}

我的问题类：

    public class Questions {

       @JsonProperty("Questions")
       private List<Questions> questions;


      @JsonCreator
      public Questions(List<Questions> questions) {
        super();
         this.questions = questions;
    }
// setters and getters
    }

Answer 1

你有很多小错误。在Questions中缺少注释，错误的字段名称或混淆Question与main()类型。我或多或少地修改了下面的代码，请参阅以下代码中的注释：

回答：

public class Answer {

  @JsonProperty("answer")
  private String answer;
  @JsonProperty("Correct") // was "correct"
  private Boolean correct;

问题：

public class Questions {

  @JsonProperty("Questions")
  private List<Question> questions;

  @JsonCreator
  public Questions(@JsonProperty("Questions") List<Question> questions) { // was missing @JsonProperty
    this.questions = questions;
  }

主要：

public static void main(String[] args) {
  ObjectMapper mapper = new ObjectMapper();
  File file = new File("question.json");

  try {
    Questions question = mapper.readValue(file, Questions.class); // was Question
    System.out.println("category.getCategory() = " + question.getQuestions().get(0).getCategory()); // corrected after changing to Questions
  } catch (IOException e) {
    e.printStackTrace();
  }
}

Answer 2

在编写用于映射json数组的java类时，要非常小心并验证将通过setter方法注入的每个字段。您的问题在于以下代码。你做的只是一个小错误。

   @JsonProperty("Questions")
   private List<Question> questions;//it should be Question object 


  @JsonCreator
  public Questions(List<Question> questions)//change the constructor accordingly

如果您仍然遇到问题，只需检查所有可能的注射是否正确。

祝好运！