java - 如何将 FasterXML\Jackson 中的 boolean 值序列化/反序列化为 Int？

Question

我正在为一个返回 Boolean 值作为“0”和“1”的服务器编写 JSON 客户端。当我尝试运行我的 JSON 客户端时，我目前收到以下异常:

HttpMessageNotReadableException: Could not read JSON: Can not construct instance of java.lang.Boolean from String value '0': only "true" or "false" recognized

那么我该如何设置 FasterXML\Jackson 以正确解析如下内容:

{
   "SomeServerType" : {
     "ID" : "12345",
     "ThisIsABoolean" : "0",
     "ThisIsABooleanToo" : "1"
   }
}

Pojo 示例:

@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonPropertyOrder({"someServerType"})
public class myPojo
{
   @JsonProperty("someServerType")
   SomeServerType someServerType;

   @JsonProperty("someServerType")
   public SomeServerType getSomeServerType() { return someServerType; }

   @JsonProperty("someServertype")
   public void setSomeServerType(SomeServerType type)
   { someServerType = type; }
}

---

@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonPropertyOrder({"someServerType"})
public class SomeServerType 
{
   @JsonProperty("ID")
   Integer ID;

   @JsonProperty("ThisIsABoolean")
   Boolean bool;

   @JsonProperty("ThisIsABooleanToo")
   Boolean boolToo;

   @JsonProperty("ID")
   public Integer getID() { return ID; }

   @JsonProperty("ID")
   public void setID(Integer id)
   { ID = id; }

   @JsonProperty("ThisIsABoolean")
   public Boolean getThisIsABoolean() { return bool; }

   @JsonProperty("ThisIsABoolean")
   public void setThisIsABoolean(Boolean b) { bool = b; }

   @JsonProperty("ThisIsABooleanToo")
   public Boolean getThisIsABooleanToo() { return boolToo; }

   @JsonProperty("ThisIsABooleanToo")
   public void setThisIsABooleanToo(Boolean b) { boolToo = b; }
}

休息客户专线
注意 1: 这是使用 Spring 3.2
注 2: toJSONString() - 是一个辅助方法，它使用 Jackson 来序列化我的参数对象
注意 3: 异常发生在读入结果对象

DocInfoResponse result = restTemplate.getForObject(docInfoURI.toString()
                                  + "/?input={input}",
                                  DocInfoResponse.class,
                                  toJSONString(params));

Answer 1

正如 Paulo Pedroso 的回答提到和引用的那样，您需要滚动自己的自定义 JsonSerializer 和 JsonDeserializer。创建后，您需要将 @JsonSerialize 和 @JsonDeserialize 注释添加到您的属性；为每个指定要使用的类。

我在下面提供了一个小(希望是简单的)示例。序列化器和反序列化器的实现都不是 super 健壮的，但这应该可以帮助您入门。

public static class SimplePojo {

    @JsonProperty
    @JsonSerialize(using=NumericBooleanSerializer.class)
    @JsonDeserialize(using=NumericBooleanDeserializer.class)
    Boolean bool;
}

public static class NumericBooleanSerializer extends JsonSerializer<Boolean> {

    @Override
    public void serialize(Boolean bool, JsonGenerator generator, SerializerProvider provider) throws IOException, JsonProcessingException {
        generator.writeString(bool ? "1" : "0");
    }   
}

public static class NumericBooleanDeserializer extends JsonDeserializer<Boolean> {

    @Override
    public Boolean deserialize(JsonParser parser, DeserializationContext context) throws IOException, JsonProcessingException {
        return !"0".equals(parser.getText());
    }       
}

@Test
public void readAndWrite() throws JsonParseException, JsonMappingException, IOException {
    ObjectMapper mapper = new ObjectMapper();

    // read it
    SimplePojo sp = mapper.readValue("{\"bool\":\"0\"}", SimplePojo.class);
    assertThat(sp.bool, is(false));

    // write it
    StringWriter writer = new StringWriter();
    mapper.writeValue(writer, sp);
    assertThat(writer.toString(), is("{\"bool\":\"0\"}"));
}