Gson反序列化具有递归依赖关系的复杂对象 [英] Gson deserialize complex object with recursive dependencies

问题描述

我有几个包含递归依赖关系的类，并使用Gson GraphAdapterBuilder将它们序列化为JSON格式，并且它完美地工作。现在我想将它们反序列化为相同的结构，但无法找到它。

I have several classes that contain a recursive dependency on each other and I serialize them to JSON format with Gson GraphAdapterBuilder, and it works perfectly. Now I want to deserialize them into the same structure but can't find out how.

我举了一个例子：

I've made an example:

class ClassA{
    public int field;
    public ClassB parent;
    public ClassA(int f, ClassB p){
        field = f;
        parent = p;
    }
}

class ClassB{
    public Vector<ClassA> vector = new Vector<ClassA>();
}

...

ClassB b = new ClassB();        

ClassA a1 = new ClassA(1,b);
ClassA a2 = new ClassA(2,b);
ClassA a3 = new ClassA(3,b);

b.vector.add(a1);
b.vector.add(a2);
b.vector.add(a3);

//Serializing object b

GsonBuilder gsonBuilder = new GsonBuilder();

new GraphAdapterBuilder()
    .addType(ClassA.class)
    .addType(ClassB.class)
    .registerOn(gsonBuilder);

Gson gson = gsonBuilder.create();

String json = gson.toJson(b);

输出给了我我想要的：

Output is giving me what I want:

{"0x1":{"vector":["0x2","0x3","0x4"]},"0x2":{"field":1,"parent":"0x1"},"0x3":{"field":2,"parent":"0x1"},"0x4":{"field":3,"parent":"0x1"}}

有没有办法将json字符串反序列化回ClassB的对象？

Is there a way to deserialize that json string back into object of ClassB?

推荐答案

好的，我找到了解决方案。这很简单。只需使用具有相同GraphAdapterBuilder结构的 fromJson 而不是 toJson 即可。

Okay, I found solution. It was very simple. Just had to use the function fromJson instead of toJson with the same GraphAdapterBuilder structure.

    ...
    GsonBuilder gsonBuilder = new GsonBuilder();
    new GraphAdapterBuilder()
            .addType(ClassA.class)
            .addType(ClassB.class)
            .registerOn(gsonBuilder);
    gson = gsonBuilder.create();
    СlassB B = gson.fromJson(json,ClassB.class);

    System.out.println("B " + B.vector);
    for(ClassA classA:B.vector){
        System.out.println(classA.field + "  " + classA.parent);
    }

输出结果为：

Output is:

    B [ClassA@10178f2b, ClassA@7ab8584d, ClassA@5cad662c]
    1  ClassB@7c0f023c
    2  ClassB@7c0f023c
    3  ClassB@7c0f023c

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