通量解码异常：意外字符 ('[' (代码91））：期望双引号开始字段名

Question

在将Flux JSON解码为Java对象时，我遇到以下异常：

2019-02-25 13:44:39.136 TRACE [{}] 25292 --- [reactor-http-nio-4] o.s.w.r.f.c.ExchangeFunctions            : [762021a9] Response 200 OK, headers={masked}
2019-02-25 13:44:39.195 ERROR [{}] 25292 --- [reactor-http-nio-4] r.M.C.2                                  : | onError(org.springframework.core.codec.DecodingException: JSON decoding error: Unexpected character ('[' (code 91)): was expecting double-quote to start field name; nested exception is com.fasterxml.jackson.core.JsonParseException: Unexpected character ('[' (code 91)): was expecting double-quote to start field name
 at [Source: UNKNOWN; line: 2, column: 3])
2019-02-25 13:44:39.196 ERROR [{}] 25292 --- [reactor-http-nio-4] r.M.C.2                                  : 
org.springframework.core.codec.DecodingException: JSON decoding error: Unexpected character ('[' (code 91)): was expecting double-quote to start field name; nested exception is com.fasterxml.jackson.core.JsonParseException: Unexpected character ('[' (code 91)): was expecting double-quote to start field name
 at [Source: UNKNOWN; line: 2, column: 3]
    at org.springframework.http.codec.json.Jackson2Tokenizer.tokenize(Jackson2Tokenizer.java:104) ~[spring-web-5.1.2.RELEASE.jar:5.1.2.RELEASE]

按以下方式设置映射器编解码器属性无法解决此问题：

mapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_FIELD_NAMES, true);

这里是JSON响应：

[
  {
    "id": "111",
    "description": "xyz"
  },
  {
    "id": "222",
    "description": "pqr"
  }
]

下面是WebClient实现：

public Mono<List<ItemServiceResponse>> getItems(ItemServiceRequest itemServiceRequest) {
return webClient
        .post()
        .contentType(MediaType.APPLICATION_JSON)
        .header(HttpHeaders.ACCEPT, MediaType.APPLICATION_STREAM_JSON.toString())
        .body(Mono.just(itemServiceRequest), ItemServiceRequest.class)
        .retrieve()
        .bodyToFlux(ItemServiceResponse.class)
        .collectList()
        .log();
}

以下是Java对象：

@Builder 
@Data 
@AllArgsConstructor 
@NoArgsConstructor 
public class ItemServiceResponse { 
  private String id; 
  private String description; 
}

Answer 1

ObjectMapper期望从您的Json响应中映射一个对象作为ItemServiceACK，因此出现异常（映射器期望引用）。

您应该更新WebClient调用，以映射ItemServiceResponse的数组：

public Mono<List<ItemServiceResponse>> getItems(ItemServiceRequest itemServiceRequest) {
    return webClient
            .post()
            .contentType(MediaType.APPLICATION_JSON)
            .header(HttpHeaders.ACCEPT, MediaType.APPLICATION_STREAM_JSON.toString())
            .body(Mono.just(itemServiceRequest), ItemServiceRequest.class)
            .retrieve()
            .bodyToFlux(ItemServiceResponse[].class) // <-- array of ItemServiceResponse
            .collectList()
            .log();
}

Answer 2

一个可怕的问题！！！我浪费了4-5天的时间来找出我的代码中的错误，并尝试了所有的排列组合，但都没有奏效。

但伙计们，邮差是罪魁祸首，是的，没错。

我得到的JSON的实际响应结构是：

{
  [
    {
      "id": "111",
      "description": "xyz"
    },
    {
      "id": "222",
      "description": "pqr"
    }
  ]
}

那是格式错误的JSON。但Postman以某种方式自动更正并给出了问题中提到的JSON的正确响应，我没有更多地关注响应，因为状态代码是200成功。

幸运的是，我触发了Curl命令并找到了根本原因。请不要相信邮递员。。。纠正不必要的事情是非常聪明的。