spring 引导 json 到 object 映射器与复杂的 json

Question

I have this list.json that I need to read to mapper object,

{
    "name":"first", 
    "identity":"gold",
    "code":{
        "csharp":{
            "input":"sample of csharp code",
            "value":[ 
                {
                "main":"true",
                "power":"low"
                }, 
                {
                "main":"false",
                "power":"low"
                }
            ],
            "description":"description of csharp code",
            "manager":"bill gates"
        }, 
        "java":{
            "input":"sample of java",
            "value":[
                {
                "main":"true",
                "power":"low"
                },
                {
                "main":"false",
                "power":"high"
                },
                {
                "main":"true",
                "power":"low"
                }
            ], 
            "description":"description of java",
            "manager":"steve job"
        }
    }
},
{
    "name":"second", 
    "identity":"diamond",
    "code":{
        "python":{
            "input":"sample of python code",
            "new":"make it more complicated with new parm not value",  // do not forget this
            "description":"description of python code",
            "manager":"john doe"
        },
        "csharp":{
            "input":"sample of csharp code",
            "value":[ 
                {
                "main":"true",
                "power":"low"
                }, 
                {
                "main":"false",
                "power":"low"
                }
            ],
            "description":"description of csharp code",
            "manager":"bill gates"
        },          
}

I omit the long list, I only put two base or outter array, but basically its about 200 or more records.

The List.class,

@Data
@AllArgsConstructor
@Entity
public class List {

    private String name;
    
    private String identity;
    
    @OneToOne(cascade = CascadeType.ALL)
    private Code[] code;
    
    public List() {}
}

Is the Code[] correct and also onetoone or onetomany?

The Code.class,

@Data
@AllArgsConstructor
@Entity
public class Code {

    <<I have no idea what to put here>>

}

Do I need to put any string variable for csharp, java, pyhton? They key should be the same as the variable in the class? But how do you do that since it's not constant?

There's a dynamic 2-layer json here in baeldung but how do I do that in the 3-layer?

Answer 1

Here's I got, you have to use JsonNode for the rest of the layers.

I didn't use this annotation for now, don't want to struggle for now, just add getter/setter and constructor using fields, maybe something to do with java 8,

@Data
@AllArgsConstructor
@Entity

@OneToOne(cascade = CascadeType.ALL)

So I remove it. Also how I did it, you have to simulate one by one in the json, meaning I have to add name and identity since those two are similar, if it works, then I add the code as JsonNode.

public class List {

    private String name;
    
    private String identity;
    
    JsonNode code;
    
    public List() {}
    
    // put getter/setter
    // put constractors as fields
}

Then on your controller,

    private String strJson = null;

    @PostConstruct
    private void loadData() {
        ClassPathResource classPathResource = new ClassPathResource("json/list.json");
        try {
            byte[] binaryData = FileCopyUtils.copyToByteArray(classPathResource.getInputStream());
            strJson = new String(binaryData, StandardCharsets.UTF_8);
        } catch (IOException e) {
            e.printStackTrace();
        }
        ObjectMapper objectMapper = new ObjectMapper();
        DataModel datam = null;
        try {
            datam = objectMapper.readValue(strJson, List.class);
        } catch (Exception e) {
            e.printStackTrace();
        }
        System.out.println(datam.code()[0].get("csharp").get("value").get("main");  // output = "true"

Thanks to Baeldung for the idea.