使用GSON进行Java到Json的验证 [英] Java to Json validation using GSON

问题描述

使用GSON API将Java对象转换为Json字符串时，如果任何注释的属性为null，我也希望此Json转换失败。 例如 p>

  public class Order {
 
 @SerializedName（orderId）
 @Expose 
 @Required 
私人整数ID; 
 
 // getter& setter for id 
} 
  

现在我正在做

  Order order = new Order（）; 
 
 JSONObject jsonobj = new JSONObject（gson.toJson（order））; 
  

如果任何@Required属性为空值$ b，我想要将上述Java转换为Json转换失败$ b是否可以使用GSON？

解决方案

如果任何Java属性为null，我想将Java转换为Json失败它被注释为@Required，
我可以使用以下方法实现此目的。如果您发现任何问题，请告诉我们：

  class RequiredKeyAdapterFactory implements TypeAdapterFactory {
 
 public< T> TypeAdapter< T>创建（Gson gson，TypeToken< T>类型）{
 
 final TypeAdapter< T> delegate = gson.getDelegateAdapter（this，type）; 
 
返回新的TypeAdapter< T>（）{
 @Override 
 public void write（JsonWriter out，T value）抛出IOException {
 if（value！= null ）{
 
 Field [] fields = value.getClass（）。getDeclaredFields（）; 
 
 for（int i = 0; i< fields.length; i ++）{
 if（fields [i] 
 .isAnnotationPresent（Required.class））{
 validateNullValue（value，fields [i]）; 
} 
 
} 
} 
 delegate.write（out，value）; 
} 
 
私人< T> void validateNullValue（T value，Field field）{
 field.setAccessible（true）; 
 Class t = field.getType（）; 
 Object v = null; 
尝试{
 v = field.get（value）; 
} catch（IllegalArgumentException | IllegalAccessException e）{
抛出new IllegalArgumentException（e）; 
} 
 if（t == boolean.class&&& Boolean.FALSE.equals（v））{
 throw new IllegalArgumentException（field +is null）; 
} else if（t.isPrimitive（）
&&（（Number）v）.doubleValue（）== 0）{
 
 throw new IllegalArgumentException（field +  一片空白）; 
} else if（！t.isPrimitive（）&& v == null）{
 throw new IllegalArgumentException（field +is null）; 
 
 
 
 $ b @Override 
 public T read（JsonReader in）throws IOException {
 return delegate.read（in）; 
} 
 
}; 
 
 
 
 RequiredKeyAdapterFactory requiredKeyAdapterFactory = new RequiredKeyAdapterFactory（）; 
 Gson gson = new GsonBuilder（）。registerTypeAdapterFactory（requiredKeyAdapterFactory）
 .create（）; 
  

这是可行的

While converting Java object to Json string using GSON API, I also want to fail this Json conversion if any of the annotated attribute is null.

For example

public class Order{

@SerializedName("orderId")
@Expose
@Required
private Integer id;

//getter & setter available for id
}

Now as I am doing

Order order = new Order();

JSONObject jsonobj = new JSONObject(gson.toJson(order));

I want to fail the above Java to Json transformation if any of the @Required attribute is null Is this possible using GSON?

解决方案

I wanted to fail Java to Json conversion, if any of the Java attribute is null which is annotated as @Required, I am able to achieve this using following approach. Please let me know if you see any issues:

class RequiredKeyAdapterFactory implements TypeAdapterFactory {

    public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {

        final TypeAdapter<T> delegate = gson.getDelegateAdapter(this, type);

        return new TypeAdapter<T>() {
            @Override
            public void write(JsonWriter out, T value) throws IOException {
                if (value != null) {

                    Field[] fields = value.getClass().getDeclaredFields();

                    for (int i = 0; i < fields.length; i++) {
                        if (fields[i]
                                .isAnnotationPresent(Required.class)) {
                            validateNullValue(value, fields[i]);
                        }

                    }
                }
                delegate.write(out, value);
            }

            private <T> void validateNullValue(T value, Field field) {
                field.setAccessible(true);
                Class t = field.getType();
                Object v = null;
                try {
                    v = field.get(value);
                } catch (IllegalArgumentException | IllegalAccessException e) {
                    throw new IllegalArgumentException(e);
                }
                if (t == boolean.class && Boolean.FALSE.equals(v)) {
                    throw new IllegalArgumentException(field + " is null");
                } else if (t.isPrimitive()
                        && ((Number) v).doubleValue() == 0) {

                    throw new IllegalArgumentException(field + " is null");
                } else if (!t.isPrimitive() && v == null) {
                    throw new IllegalArgumentException(field + " is null");

                }
            }

            @Override
            public T read(JsonReader in) throws IOException {
                return delegate.read(in);
            }

        };
    }
}

RequiredKeyAdapterFactory requiredKeyAdapterFactory = new RequiredKeyAdapterFactory();
Gson gson = new GsonBuilder().registerTypeAdapterFactory(requiredKeyAdapterFactory)
        .create();

This is working

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