java - 从 JSON 响应(Spring REST)中删除空对象和空对象，空对象内有空对象

Question

我想从 JSON 响应中删除 Null 和 Empty 值。

下面是 Json 字符串:

{"implDisplayablePricePlan": [
          {
            "productSpecPricing": {
              "childPricingSchema": {}
            },
            "assignedPricePlanID": "abc",
            "name": "GOLD",
            "action": "Something",
            "status": "Something",
            "selected": true,
            "crossProductDiscount": false,

            "displayInformation": {
              "visible": true,
              "enabled": false
            }
          }]

}

在本例中:productSpecPricing 与 childPricingSchema

删除对于任何 JSON 字符串通用的空对象的最佳方法是什么。

Answer 1

使用Jackson您可以轻松设置首选项来序列化对象

ObjectMapper objectMapper = new ObjectMapper();
objectMapper.enable(SerializationFeature.INDENT_OUTPUT);
objectMapper.setSerializationInclusion(Include.NON_NULL);
objectMapper.setSerializationInclusion(Include.NON_EMPTY);
ObjectWriter writer = objectMapper.writer();
System.out.println(writer.writeValueAsString(YOUR_OBJECT));

我得到了这个:

{
  "implDisplayablePricePlan" : [ {
    "productSpecPricing" : { },
    "assignedPricePlanID" : "abc",
    "name" : "GOLD",
    "action" : "Something",
    "status" : "Something",
    "selected" : true,
    "crossProductDiscount" : false,
    "displayInformation" : {
      "visible" : true,
      "enalble" : false
    }
  } ]
}

因为 productSpecPricing 不为 null(或空数组/集合)，所以要解决这个问题，您必须添加一个过滤器:

使用 @JsonFilter("myFilter") 注释包含 productSpecPricing 属性的类

FilterProvider filters = new SimpleFilterProvider().addFilter("myFilter", filter);
ObjectWriter writer = objectMapper.writer(filters);

过滤器:

PropertyFilter filter = new SimpleBeanPropertyFilter() {

    @Override
    public void serializeAsField(Object pojo, JsonGenerator jgen,
            SerializerProvider provider, PropertyWriter writer)
                    throws Exception {
        if (include(writer)) {
            System.out.println(writer.getName());
            if (!writer.getName().equals("productSpecPricing")) {
                writer.serializeAsField(pojo, jgen, provider);
                return;
            } else {
                ProductSpecPricing productSpecPricing = ((YOU_OBJECT) pojo).getProductSpecPricing();
                if (productSpecPricing != null && productSpecPricing.getChildPricingSchema() != null && !productSpecPricing.getChildPricingSchema().isEmpty()) {
                    writer.serializeAsField(pojo, jgen, provider);
                }
            }
        } else if (!jgen.canOmitFields()) {
            writer.serializeAsOmittedField(pojo, jgen, provider);
        }
    }

    @Override
    protected boolean include(PropertyWriter writer) {
        return true;
    }

    @Override
    protected boolean include(BeanPropertyWriter writer) {
        return true;
    }
};

应用过滤器后的结果是:

{
  "implDisplayablePricePlan" : [ {
    "assignedPricePlanID" : "abc",
    "name" : "GOLD",
    "action" : "Something",
    "status" : "Something",
    "selected" : true,
    "crossProductDiscount" : false,
    "displayInformation" : {
      "visible" : true,
      "enalble" : false
    }
  } ]
}