如何为 JsonObjects 的 JsonObject 创建 Jackson XML POJO class

Question

我正在尝试为以下 JSON 结构创建 POJO。 Fields 节点很容易连接起来，但我不确定如何使用注释来连接 Description 节点。如果我一直在为该节点定义 JSON 结构，我会创建一个 JsonObjects 的 JsonArray，这将使 java class 变得容易，但由于我没有，我需要弄清楚如何序列化下面的结构：

{
    "Fields": {
        "Required": ["ftp.hostname"],
        "Optional": ["ftp.rootDirectory"]
    },
    "Description": {
        "ftp.hostname": {
            "label": "SFTP Hostname",
            "description": "SFTP server hostname or IP address"
        },
        "ftp.rootDirectory": {
            "label": "Root Directory",
            "description": "The root path on the Data Store accessible by this connector"
        }
    }
}

请注意，Description 对象中的节点名称与 Fields 节点中定义的值相关，这意味着它们的节点名称可能因有效负载而异。

Fields节点的class：

public class FieldDetails {

    public static final String REQUIRED = "Required";
    public static final String OPTIONAL = "Optional";

    @JsonProperty(value = REQUIRED, required = true)
    private List<String> required;

    @JsonProperty(value = OPTIONAL, required = true)
    private List<String> optional;
}

到目前为止我对整个对象的了解：

public class FieldDefinitions {

    public static final String FIELDS = "Fields";
    public static final String DESCRIPTION = "Description";

    @JsonProperty(value = FIELDS, required = true)
    private FieldDetails fields;

    @JsonProperty(value = DESCRIPTION , required = true)
    private ??? descriptions;
}

Answer 1

就是这个结构。

public class FieldDefinitions {
    @JsonProperty("Fields")
    public FieldDetails fields = new FieldDetails();

    @JsonProperty("Description")
    public Map<String, Property> properties = new HashMap<>();
}

public class FieldDetails {
    @JsonProperty("Required")
    public List<String> required = new ArrayList<>();

    @JsonProperty("Optional")
    public List<String> optional = new ArrayList<>();
}

public class Property {
    public String label;
    public String description;
}

Answer 2

通常，您总是可以将任何 JSON 对象映射到 Map<String, Object>。如果 JSON 包含许多嵌套对象，Jackson 将自动选择正确的类型：Map 用于对象，List 用于数组。

您还可以像下面那样为 Description 属性声明 class。

class Description {
    private String label;
    private String description;
    // getters, setters, toString
}

整个 Description 是一个很大的 JSON，您可以将其映射到 Map<String, Description>。因此，它可能如下所示：

class FieldDefinitions {

    public static final String FIELDS = "Fields";
    public static final String DESCRIPTION = "Description";

    @JsonProperty(value = FIELDS, required = true)
    private FieldDetails fields;

    @JsonProperty(value = DESCRIPTION, required = true)
    private Map<String, Description> descriptions;

    // getters, setters, toString
}

其余同理。示例应用程序：

import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.databind.ObjectMapper;

import java.io.File;
import java.util.List;
import java.util.Map;

public class JsonApp {

    public static void main(String[] args) throws Exception {
        File json = new File("./resource/test.json").getAbsoluteFile();

        ObjectMapper mapper = new ObjectMapper();

        FieldDefinitions fields = mapper.readValue(json, FieldDefinitions.class);
        System.out.println("Required");
        fields.getFields().getRequired().forEach(r ->
                System.out.println(r + " = " + fields.getDescriptions().get(r)));
        System.out.println("Optional");
        fields.getFields().getOptional().forEach(r ->
                System.out.println(r + " = " + fields.getDescriptions().get(r)));
    }
}

对于给定的 JSON payload 打印：

Required
ftp.hostname = Description{label='SFTP Hostname', description='SFTP server hostname or IP address'}
Optional
ftp.rootDirectory = Description{label='Root Directory', description='The root path on the Data Store accessible by this connector'}

如何为 JsonObjects 的 JsonObject 创建 Jackson XML POJO class

How to create Jackson XML POJO class for a JsonObject of JsonObjects

java

json

pojo

jackson