带有子对象的pojos的JSON序列化 [英] JSON Serialization of pojos with child objects

问题描述

假设我有一个具有以下接口的宁静的Web服务:

Let's say I have a restful webservice with the following interfaces:

GET /some/parent

这将返回类似的内容

[
    {
        urn: "/some/parent/1",
        name: "parent1",
        children: [ "/some/child1", "/some/child2" ]
    },
    {
        urn: "/some/parent/2",
        name: "parent2",
        children: [ "/some/child3", "/some/child4" ]
    }
]

而且，我已经

GET /some/parent/{id}

返回如下内容:

{
    urn: /some/parent/1,
    name: parent1,
    children: [
        {
            urn: "/some/child1",
            name: "child1"
        },
        {
            urn: "/some/child2",
            name: "child2"
        }
    ]
}

因此，当请求父母列表时，每个父母的json表示形式将与孩子骨灰盒一起列出.请求特定的父资源时，json表示形式将包含子json表示形式的列表.

So, when requesting a list of parents, the json representations for every parent will be list with the child urns. When requesting a specific parent resource the json representation will contain a list of child json representations.

使用jersey的常见方法是定义两个简单的Java pojos和一个简单的Resource:

With jersey the common way would be to define two simple java pojos and a simple Resource:

public class Parent {
    private String id;
    private String name;
    private List<String> childIds;
    ...
    @JsonIgnore
    public String getId()...
    @JsonProperty
    public String getUrn()...
}

public class Child {
    private String id:
    private String name;
    ...
    @JsonIgnore
    public String getId()...
    @JsonProperty
    public String getUrn()...
}

@Path("/some/parent")
@Produces(MediaType.APPLICATION_JSON)
public class ParentResource() {
    @GET
    public List<Parent> findAll() {
        List<Parent> result = // some database query call
        return result;
    }

    @GET
    @Path("{id}")
    public Parent find(@PathParam("id") String id) {
        Parent parent = // some database call
        return parent;
    }
}

在上述情况下如何注入儿童the/物体?有没有最佳做法?您如何解决这个问题?

How can I inject the child urns/objects in the above scenarios? Are there any best practices? How do you solve this?

谢谢.

推荐答案

在这种情况下，我宁愿制作一个扩展的Parent类，如下所示:

In this case I would rather make an extended Parent class like this:

public class ParentExtended extends Parent {
    private List<Child> childrenObjects;

    public ParentExtended(Parent parent) {
        this.id = parent.getId();
        ...
    }

    @JsonProperty("children")
    public List<Child> getChildrenObjects() { ... }

    @Override
    @JsonIgnore
    public List<String> getChildren() { ... }
}


@Path("/some/parent")
@Produces(MediaType.APPLICATION_JSON)
public class ParentResource() {
    @GET
    public List<Parent> findAll() {
        List<Parent> result = // some database query call
        return result;
    }

    @GET
    @Path("{id}")
    public ParentExtended find(@PathParam("id") String id) {
        Parent parent = // some database call
        ParentExtended parentEx = new ParentExtended(parent);

        for (String childId : parent.getChildren()) {
            parentEx.getChildrenObjects().add(// fetch the child object);
        }
        return parentEx;
    }
}

这不是一个很好的方法.我愿意接受其他选择...

It is not a very nice way. I am open to other alternatives...

这篇关于带有子对象的pojos的JSON序列化的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！