Java 在Spring boot中使用post方法保存多个实体时的无限循环

为了解释我正在处理的问题，我将首先提供代码

往复式控制器 用户控制器 例外情况 问题

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因此，当我调用该方法添加配方时，我希望数据库知道有一个新配方，并且新配方链接到添加它的用户。当我删除保存用户实体的部分时，根本不进行映射。但是，当我使用userRepository告诉数据库已经进行了更改（将配方添加到他们的列表中）时，似乎有一个无限的添加新用户的循环。

回答您的问题并包括您评论中的最后要求

如果您想打破循环，但有些人想以某种方式保留嵌套对象，我建议编写一个自定义序列化程序，并将导致无休止递归的对象替换为其他字段（在下面的示例中，我使用了author username，它是

String

，而不是

author

对象）

为了重现这个案例，我创建了一个模拟模型，它与您的模型类似

配方：

public class Recipe {

    private EvaUser author;
    private String name = "test";
    private String ingridients = "carrots, tomatos";

    public EvaUser getAuthor() {
        return author;
    }

    public void setAuthor(EvaUser author) {
        this.author = author;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getIngridients() {
        return ingridients;
    }

    public void setIngridients(String ingridients) {
        this.ingridients = ingridients;
    }
}

public class EvaUser {

    private List<Recipe> myRecipes = new ArrayList<>();
    private List<Recipe> favoriteRecipes = new ArrayList<>();
    private String username;

    public List<Recipe> getMyRecipes() {
        return myRecipes;
    }

    public void setMyRecipes(List<Recipe> myRecipes) {
        this.myRecipes = myRecipes;
    }

    public List<Recipe> getFavoriteRecipes() {
        return favoriteRecipes;
    }

    public void setFavoriteRecipes(List<Recipe> favoriteRecipes) {
        this.favoriteRecipes = favoriteRecipes;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }
}

EvaUser：

public class Recipe {

    private EvaUser author;
    private String name = "test";
    private String ingridients = "carrots, tomatos";

    public EvaUser getAuthor() {
        return author;
    }

    public void setAuthor(EvaUser author) {
        this.author = author;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getIngridients() {
        return ingridients;
    }

    public void setIngridients(String ingridients) {
        this.ingridients = ingridients;
    }
}

public class EvaUser {

    private List<Recipe> myRecipes = new ArrayList<>();
    private List<Recipe> favoriteRecipes = new ArrayList<>();
    private String username;

    public List<Recipe> getMyRecipes() {
        return myRecipes;
    }

    public void setMyRecipes(List<Recipe> myRecipes) {
        this.myRecipes = myRecipes;
    }

    public List<Recipe> getFavoriteRecipes() {
        return favoriteRecipes;
    }

    public void setFavoriteRecipes(List<Recipe> favoriteRecipes) {
        this.favoriteRecipes = favoriteRecipes;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }
}

来自控制器的

EvaUser

的JSON响应主体（前一个是

StackOverflowerError

）：

---

可能重复：@MehrajMalik这个问题和答案似乎有点过时了。我觉得这个对我没什么帮助。无论如何，谢谢。所有的技巧对当前任务也有效。这是由保存操作引起的吗？在我看来，Jackson似乎正试图在你的

getAllUsers（）

中序列化你的

EvaUser

，因为它引用了

Recipe

，并且

Recipe

引用了

EvaUser

，它无法正确地序列化它，并最终进入映射该链的无限循环。通过添加

@JsonIgnore

来打破该链的@MehrajMalik提供的答案实际上是一个正确的解决方案，并且没有过时。只是偶然发现了答案。我确实犯了一个错误，使用author作为一个对象，其中也包含recipe，导致了一个循环。非常感谢。

Failed to write HTTP message: 
org.springframework.http.converter.HttpMessageNotWritableException: Could 
not write content: Infinite recursion

public class Recipe {

    private EvaUser author;
    private String name = "test";
    private String ingridients = "carrots, tomatos";

    public EvaUser getAuthor() {
        return author;
    }

    public void setAuthor(EvaUser author) {
        this.author = author;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getIngridients() {
        return ingridients;
    }

    public void setIngridients(String ingridients) {
        this.ingridients = ingridients;
    }
}

public class EvaUser {

    private List<Recipe> myRecipes = new ArrayList<>();
    private List<Recipe> favoriteRecipes = new ArrayList<>();
    private String username;

    public List<Recipe> getMyRecipes() {
        return myRecipes;
    }

    public void setMyRecipes(List<Recipe> myRecipes) {
        this.myRecipes = myRecipes;
    }

    public List<Recipe> getFavoriteRecipes() {
        return favoriteRecipes;
    }

    public void setFavoriteRecipes(List<Recipe> favoriteRecipes) {
        this.favoriteRecipes = favoriteRecipes;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }
}

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.ser.std.StdSerializer;

import java.io.IOException;
import java.util.Optional;

public class RecipeSerializer extends StdSerializer<Recipe> {

    protected RecipeSerializer() {
        this(null);
    }

    protected RecipeSerializer(Class<Recipe> t) {
        super(t);
    }

    @Override
    public void serialize(Recipe recipe, JsonGenerator gen, SerializerProvider provider) throws IOException {
        gen.writeStartObject();

        gen.writeStringField("name", recipe.getName());
        gen.writeStringField("author", Optional.ofNullable(recipe.getAuthor().getUsername()).orElse("null"));
        gen.writeStringField("ingridients", recipe.getIngridients());

        gen.writeEndObject();
    }
}

@JsonSerialize(using = RecipeSerializer.class)
public class Recipe {
    // model entity
}

{
    "myRecipes": [
        {
            "name": "soup",
            "author": "user1",
            "ingridients": "carrots, tomatos"
        },
        {
            "name": "steak",
            "author": "user1",
            "ingridients": "meat, salt"
        }
    ],
    "favoriteRecipes": [
        {
            "name": "soup",
            "author": "user1",
            "ingridients": "carrots, tomatos"
        },
        {
            "name": "steak",
            "author": "user1",
            "ingridients": "meat, salt"
        }
    ],
    "username": "user1"
}