Spring boot 如何防止RestController中的递归结果？

课程：

@Entity
@Table(name = "question")
@Data
@NoArgsConstructor
public class Question {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;

@Column
private String text;

@OneToMany(mappedBy="question", fetch = FetchType.LAZY)
private List<Answer> answers;

public void addAnswer(Answer answer){
    answer.setQuestion(this);
    this.answers.add(answer);
}
}

@Entity
@Table(name = "answer")
@Data
@NoArgsConstructor
public class Answer {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;

@Column
private String text;

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name="question_id")
private Question question;
}

它不应该返回这样的结果吗：

{
"text": "something else again",
"question": {
    "id": 4,
    "text": "question 3",
    "answers": [
        {
            "id": 1,
            "text": "something"
         }
    ]
}

---

这取决于将对象序列化为JSON所使用的JSON库。如果您正在使用Jackson，您可以使用

@JsonIgnoreProperties

来打破循环：

@实体
@表（name=“问题”）
公开课问题{
[....]
@JsonIgnoreProperties（“问题”）
公共列表getAnswers（）{
返回答案；
}
}

如果你得到答案，同样的问题可能会发生，因此你可能还需要打破这个循环：

@实体
@表（name=“answer”）
公开课答案{
[....]
@JsonIgnoreProperties（“答案”）
公共问题{
返回问题；
}
}

不要将实体用作控制器方法的返回值。了解3层architecture@Jens谢谢我在学习，所以一步一个脚印。谢谢肯。我安装了Jackson，它解决了这个问题。

{
"text": "something else again",
"question": {
    "id": 4,
    "text": "question 3",
    "answers": [
        {
            "id": 1,
            "text": "something",
            "question": {
                "id": 4,
                "text": "question 3",
                "answers": [
                    {
                        "id": 1,
                        "text": "something",
                        "question": {
                            "id": 4,
                            "text": "question 3",
                            "answers": [
                                {
                                    "id": 1,
                                    "text": "something",
                                    "question": {
                                        "id": 4,
                                        "text": "question 3",
                                        "answers": [
                                            {
                                                "id": 1,
                                                "text": "something",
                                                "question": {
                                                    "id": 4,
                                                    "text": "question 3",
                                                    "answers": [
                                                        {
                                                            "id": 1,
                                                            "text": "something",
                                                            "question": {
                                                                "id": 4,
                                                                "text": "question 3",
                                                                "answers": [
                                                                    {
                                                                        "id": 1,
                                                                        "text": "something",
                                                                        "question": {
                                                                            "id": 4,
                                                                            "text": "question 3",
                                                                            "answers": [
                                                                                {
                                                                                    "id": 1,
                                                                                    "text": "something",
                                                                                    "question": {
                                                                                        "id": 4,
                                                                                        "text": "question 3",
                                                                                        "answers": [
                                                                                            {
                                                                                                "id": 1,
                                                                                                "text": "something",
                                                                                                "question": {
                                                                                                    "id": 4,
                                                                                                    "text": "question 3",
                                                                                                    "answers": [

{
"text": "something else again",
"question": {
    "id": 4,
    "text": "question 3",
    "answers": [
        {
            "id": 1,
            "text": "something"
         }
    ]
}