java - 需要一个字符串，但结果是 BEGIN_OBJECT 我必须返回字符串

Question

类别

 class PrintRequest {
        private String data;
        private String userImageBase64;
        private String organizationImageBase64;
        private String fileBase64;
     //getters and setters
    }

使用PrintRequest printRequest = gson.fromJson(request.getBody(), PrintRequest.class);

json

{ 
   "data":{ 
      "nazwaDostawcy":"nazwa dostawcy (opis)",
      "nazwa":"Gniazdo przemysłowe, kątowe, 2p+E, 16A, 100...130 V AC, IP 44 ",
      "kod":"val",
      "kodEan":"val",
      "kodWewnrtrzny":"val",
      "cennaNetto":"val"
   },
   "fileBase64":""
}

就像在主题中一样，我明白为什么会收到此错误，但我需要以字符串形式返回data。我怎样才能实现我的目标？

感谢您的帮助!

Answer 1

这是无需创建自定义 gson 序列化的最简单方法。只需重写 toString() 方法

public class PrintRequest {
     private Value data;
     private String userImageBase64;
     private String organizationImageBase64;
     private String fileBase64;
     //getters and setters
}

public class Value {
    String nazwaDostawcy;

    @Override
    public String toString() {
        return "Value{" +
            "nazwaDostawcy='" + nazwaDostawcy + '\'' +
            ", nazwa='" + nazwa + '\'' +
            ", kod='" + kod + '\'' +
            ", kodEan='" + kodEan + '\'' +
            ", kodWewnrtrzny='" + kodWewnrtrzny + '\'' +
            ", cennaNetto='" + cennaNetto + '\'' +
            ", kategoria='" + kategoria + '\'' +
            ", opis='" + opis + '\'' +
            ", logo1='" + logo1 + '\'' +
            ", logo2='" + logo2 + '\'' +
            '}';
}

String nazwa;
String kod;
String kodEan;
String kodWewnrtrzny;
String cennaNetto;
String kategoria;
String opis;
String logo1;
String logo2;
//getters and setters
}

用法:

PrintRequest printRequest = gson.fromJson(json, PrintRequest.class); System.out.println(printRequest.getData().toString());

更新:

使用自定义 JsonDeserializer 的解决方案

public class CustomJsonDeserializer implements JsonDeserializer<PrintRequest> {

    @Override
    public PrintRequest deserialize(JsonElement jsonElement, Type type, JsonDeserializationContext jsonDeserializationContext) throws JsonParseException {
        PrintRequest printRequest = new PrintRequest();
        JsonObject jsonObject = jsonElement.getAsJsonObject();
        String dataStr="";
        JsonObject jsonObjectData = jsonObject.getAsJsonObject("data");
        for (Data data : Data.values()) {
            dataStr+=(data.name() + ":" + jsonObjectData.get(data.name()).getAsString()+",\n");
        }
        printRequest.setData(dataStr);
        return printRequest;
    }
}


public enum Data {
    nazwaDostawcy,
    nazwa
}

public class PrintRequest {
    private String data;
    private String userImageBase64;
    private String organizationImageBase64;
    private String fileBase64;
    //getters and setters

用法:

GsonBuilder gsonBuilder = new GsonBuilder();
        gsonBuilder.setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES);
        gsonBuilder.registerTypeAdapter(PrintRequest.class, new CustomJsonDeserializer());
        Gson gson = gsonBuilder.create();
        PrintRequest printRequest = gson.fromJson(json, PrintRequest.class);
        System.out.println(printRequest.getData());