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Jackson反序列化SNS消息錯(cuò)誤MismatchedInputException

Java

叮當(dāng)貓咪 2023-09-20 15:21:37

我正在編寫一個(gè)通過(guò) SNS HTTP 請(qǐng)求處理來(lái)自 Amazon Simple Email Service 的回調(diào)的功能。我想將亞馬遜提供的消息解析為本地對(duì)象結(jié)構(gòu)。問(wèn)題是 SNS 將 JSON 消息包裝成字符串，并且 Jackson 無(wú)法解析它。我收到錯(cuò)誤：com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of `xxx.email.domain.aws.ses.Notification` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('{"notificationType":"Delivery","mail":{"timestamp":"2019-10-02T14:43:14.570Z" ... next values of the message ... }}')來(lái)自 SNS 的整條消息如下所示： { "Type" : "Notification", "MessageId" : "4944xxxx-711d-57d4-91b8-8215cxxxxx", "TopicArn" : "arn:aws:sns:eu-west-1:...", "Message" : "{\"notificationType\":\"Delivery\",\"mail\":{\"timestamp\":\"2019-10-02T14:43:14.570Z\", ... next values of the message ... },\"delivery\":{\"timestamp\":\"2019-10-02T14:43:16.030Z\", ... next values of the message ... }}", "Timestamp" : "2019-10-02T14:43:16.062Z", "SignatureVersion" : "1", "Signature" : "signature base64", "SigningCertURL" : "cert url", "UnsubscribeURL" : "unsubscribe url"}我的實(shí)際本地結(jié)構(gòu)如下所示：@Data@JsonNaming(PropertyNamingStrategy.UpperCamelCaseStrategy.class)public class MessageWrapper { private String type; private String messageId; private String topicArn; private Notification message; private Date timestamp; private String signatureVersion; private String signature; private String signingCertURL; private String unsubscribeURL;}@Datapublic class Notification { private String notificationType; private Mail mail;}@Datapublic class Mail { private String messageId; private String source; private String sourceArn; private String sourceIp; private String sendingAccountId; private String[] destination;}我正在尋找某種方法來(lái)告訴 JacksonMessage應(yīng)該從字符串中提取并視為普通的 JSON。編輯反序列化private MessageWrapper deserializeMessage(String message) throws IOException { return new ObjectMapper().readValue(message, MessageWrapper.class);}

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2 回答

天涯盡頭無(wú)女友

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我認(rèn)為要解決這個(gè)問(wèn)題，您需要一個(gè)用于類Notification中字段的自定義反序列化器MessageWrapper以及一個(gè)用于類Mail中字段的自定義反序列化器Notification，如下所示：

public class NotificationDeserializer extends JsonDeserializer<Notification> {

@Override

public Notification deserialize(JsonParser p, DeserializationContext ctxt)

throws IOException, JsonProcessingException {

String text = p.getText();

return new ObjectMapper().readValue(text, Notification.class);

}

public class MailDeserializer extends JsonDeserializer<Mail> {

@Override

public Mail deserialize(JsonParser p, DeserializationContext ctxt)

throws IOException, JsonProcessingException {

String text = p.getText();

return new ObjectMapper().readValue(text, Mail.class);

}

在您的類上添加一些注釋，如下所示：

@Data

@JsonNaming(PropertyNamingStrategy.UpperCamelCaseStrategy.class)

public class MessageWrapper {

private String type;

private String messageId;

private String topicArn;

@JsonDeserialize(using = NotificationDeserializer.class)

private Notification message;

private Date timestamp;

private String signatureVersion;

private String signature;

private String signingCertURL;

private String unsubscribeURL;

}

@Data

public class Notification {

private String notificationType;

@JsonDeserialize(using = MailDeserializer.class)

private Mail mail;

}

@Data

public class Mail {

private String messageId;

private String source;

private String sourceArn;

private String sourceIp;

private String sendingAccountId;

private String[] destination;

}

編輯1

實(shí)際上并不MailDeserializer需要。獨(dú)自NotificationDeserializer解決這個(gè)問(wèn)題。

編輯2

在自定義解串器中使用新的ObjectMapper是必須的。

反對(duì) 回復(fù) 2023-09-20

慕雪6442864

TA貢獻(xiàn)1812條經(jīng)驗(yàn) 獲得超5個(gè)贊

messageproperty 的類型為 type Notification，但Jackson預(yù)期JSON Object不是string value。在這種情況下，您可以創(chuàng)建自定義反序列化器或通過(guò)某種環(huán)回實(shí)現(xiàn)來(lái)實(shí)現(xiàn)通用解決方案。如果給定的有效負(fù)載不是 aJSON Object將其讀取為 aString并使用 this 再次調(diào)用反序列化String。

為了避免StackOverflowError您需要使用另一個(gè)實(shí)例ObjectMapper或使用BeanDeserializerModifier保留BeanDeserializer實(shí)例并在遇到的地方使用它JSON Object。簡(jiǎn)單的例子如下所示：

import com.fasterxml.jackson.core.JsonParser;

import com.fasterxml.jackson.core.JsonToken;

import com.fasterxml.jackson.databind.BeanDescription;

import com.fasterxml.jackson.databind.DeserializationConfig;

import com.fasterxml.jackson.databind.DeserializationContext;

import com.fasterxml.jackson.databind.DeserializationFeature;

import com.fasterxml.jackson.databind.JsonDeserializer;

import com.fasterxml.jackson.databind.ObjectMapper;

import com.fasterxml.jackson.databind.PropertyNamingStrategy;

import com.fasterxml.jackson.databind.annotation.JsonNaming;

import com.fasterxml.jackson.databind.deser.BeanDeserializer;

import com.fasterxml.jackson.databind.deser.BeanDeserializerBase;

import com.fasterxml.jackson.databind.deser.BeanDeserializerModifier;

import com.fasterxml.jackson.databind.module.SimpleModule;

import com.fasterxml.jackson.databind.node.TextNode;

import lombok.Data;

import lombok.ToString;

import java.io.File;

import java.io.IOException;

import java.util.Collections;

import java.util.Date;

import java.util.Objects;

import java.util.Set;

public class JsonApp {

public static void main(String[] args) throws Exception {

File jsonFile = new File("./resource/test.json").getAbsoluteFile();

SimpleModule loopBackModule = new SimpleModule();

loopBackModule.setDeserializerModifier(new LoopBackBeanDeserializerModifier(Collections.singleton(Notification.class)));

ObjectMapper mapper = new ObjectMapper();

mapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);

mapper.registerModule(loopBackModule);

MessageWrapper wrapper = mapper.readValue(jsonFile, MessageWrapper.class);

System.out.println(wrapper.getMessage());

}

class LoopBackBeanDeserializerModifier extends BeanDeserializerModifier {

private final Set<Class> allowedClasses;

LoopBackBeanDeserializerModifier(Set<Class> allowedClasses) {

this.allowedClasses = Objects.requireNonNull(allowedClasses);

}

@Override

public JsonDeserializer<?> modifyDeserializer(DeserializationConfig config, BeanDescription beanDesc, JsonDeserializer<?> deserializer) {

if (allowedClasses.contains(beanDesc.getBeanClass())) {

return new LoopBackBeanDeserializer<>((BeanDeserializerBase) deserializer);

}

return deserializer;

}

class LoopBackBeanDeserializer<T> extends BeanDeserializer {

private final BeanDeserializerBase baseDeserializer;

protected LoopBackBeanDeserializer(BeanDeserializerBase src) {

super(src);

this.baseDeserializer = src;

}

@Override

public T deserialize(JsonParser p, DeserializationContext ctxt) throws IOException {

// if first token is VALUE_STRING we should read it as String and

// run deserialization process again based on this String.

if (p.currentToken() == JsonToken.VALUE_STRING) {

return (T) ((ObjectMapper) p.getCodec()).readValue(p.getText(), _valueClass);

}

// vanilla bean deserialization

return (T) baseDeserializer.deserialize(p, ctxt);

}

POJO型號(hào)是一樣的。您只需要列出您期望某些問(wèn)題和loop-back機(jī)制適用于它們的類。

反對(duì) 回復(fù) 2023-09-20

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Jackson反序列化SNS消息錯(cuò)誤MismatchedInputException

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