如何使用此特定结构创建JSON数组？

Question

I intend to create a JSON Array with the following structure. The metadata tag is going to constant in all the entries. I am stumped.

[{
        "metadata": {
            "Value": "String"
        },
        "name": "String",
        "id": "String"
    },
    {
        "metadata": {
            "Value": "String"
        },
        "name": "String",
        "id": "String"
    }
]

Answer 1

public class yourJsonObject {

private Map<String, String> metadata;

private String name;

private string id;

public yourJsonObject() {

}

public Map<String, String> getMetadata(){
return metadata;
}

public void setMetadata(Map<String, String> metadata){
this.metadata = metadata;
}

public String getName(){
return name;
}

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

public String getId(){
return id;
}

public void setId(String id){
this.id = id;
}

}

Then somewhere else you can just do this:

ObjectMapper mapper = new ObjectMapper(); // create once, reuse
yourJsonObject example = new yourJsonObject(); // have your POJO you want to save
mapper.writeValue(new File("result.json"), example);

To read you can just use:

ObjectMapper mapper = new ObjectMapper(); // create once, reuse
yourJsonObject value = mapper.readValue(new File("data.json"), yourJsonObject .class);

Both snippets are taken from my linked wiki article from jackson themselves.

Jackson should automatically be able to parse this POJO to an equivalent JSON if configured correctly. Note: Jackson has to be globally registered and has to know about it. Please read the wiki of what you use to know about it... Jackson in 5 Minutes

Else you could just manually build the JSON like Neeraj said.

Answer 2

JSONArray array = new JSONArray(); // Create JSONArray Object

JSONObject jsonObject = new JSONObject(); // Your JSONObject which gets added into array
jsonObject.put("metadata",new MetaDataCustomClass("SomeRandomStringValue"));
jsonObject.put("name", "Neeraj");
jsonObject.put("id", "123");

array.add(jsonObject); // Here you push the jsonObject into Array.

Note: MetaDataCustomClass is just a custom Class having a Value instance variable of type String.

Class MetaDataCustomClass {

   private String value;

   public MetaDataCustomClass(String value){
       this.value = value;
   }

}