jackson序列化不包括双值0.0。

Question

当试图将双值映射/设置为0.0时，ObjectMapper将其视为等于null，从而排除了比较相等时的情况。

我有下面的测试用例：

import com.fasterxml.jackson.annotation.JsonInclude.Include;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.util.Map;
import lombok.Getter;
import lombok.Setter;
import net.javacrumbs.jsonunit.JsonAssert;
import org.junit.Test;

public class ValidJson {

@Getter
@Setter
static class Temp {
  Double dblValue;
  Integer intVal;
  boolean valid = false;
}

@Test
public void validJson() throws Exception {
    ObjectMapper objectMapper = new ObjectMapper();
    objectMapper.setSerializationInclusion(Include.NON_NULL);
    objectMapper.setSerializationInclusion(Include.NON_DEFAULT);

    String json = "{\"dblValue\":0.0}";
    Temp generatedObj = objectMapper.readValue(json, Temp.class);
    Map<?, ?> originalJsonMap = objectMapper.readValue(json, Map.class);

    JsonNode generatedObjMap = objectMapper.valueToTree(generatedObj);
    JsonNode originalObjMap = objectMapper.valueToTree(originalJsonMap);
    Assert.assertSame(originalObjMap, generatedObjMap);
  }
}

上述测试用例失败，断言错误为java.lang.AssertionError: JSON documents are different: Different keys found in node "". Expected [dblValue], got []. Missing: "dblValue"

但是，当我将String json = "{\"dblValue\":0.0}";更改为String json = "{\"dblValue\":1.0}";时，测试就会通过。

我认为与杰克逊一起出现了双倍的违约行为，我无法解决我的上述问题。杰克逊诉2.8.10

Answer 1

这里的问题是：

objectMapper.setSerializationInclusion(Include.NON_DEFAULT);

双值0.0被视为默认值，而Jackson则忽略它。移除这一行后，一切都应该正常工作。如果不希望包含布尔值有效= false，请为有效字段添加@JsonInclude注释，如下所示：

@JsonInclude(Include.NON_DEFAULT)
boolean valid = false;