从 Java 中返回的 JSON 对象中检索值

Question

我是一个接收 JSON 对象的人，我需要将值保存到我的数据库中。但我在弄清楚如何检索 JSON 对象中的特定值时遇到了问题。

在这种情况下，我想检索 'originationNumber' 和 'messageBody' 的值

响应对象 -

{"originationNumber":"***","destinationNumber":"***","messageKeyword":"KEYWORD_***","messageBody":"Answer ","previousPublishedMessageId":"1slamq6mdpucd8q4i7iabf1sikc629ga253tr6o0","inboundMessageId":"88bc02fc-aff3-4277-ac1d-f27b6d3b6abb"}

接收消息的方法-

public String getReceivedMessages(Messaging receivedMessage) {

    BasicAWSCredentials awsCredentials = new BasicAWSCredentials(awsAccessKey, awsSecretKey);
    AmazonSQS sqsClient = AmazonSQSClientBuilder.standard()
            .withCredentials(new AWSStaticCredentialsProvider(awsCredentials))
            .withRegion(String.valueOf(awsRegion)).build();

    StringBuilder sb = new StringBuilder();
    String queueUrl = "https://sqs.us-east-1.amazonaws.com/1234567/GetReceivedMessages";
    List<Message> messages = sqsClient.receiveMessage(new ReceiveMessageRequest(queueUrl)
            .withMaxNumberOfMessages(1).withWaitTimeSeconds(20)).getMessages();
    for (Message message : messages) {
        sb.append(message.getBody());
        sqsClient.deleteMessage(queueUrl, message.getReceiptHandle());
    }

    // Save messages to DB
    String userId = connectionRequestRepository.getUserId();
    Date date = new Date();
    Timestamp now = new Timestamp(date.getTime());

    receivedMessage.setUserId(userId);
    receivedMessage.setOriginationNumber("");
    receivedMessage.setDestinationNumber("***");
    receivedMessage.setMessageBody("");
    receivedMessage.setMessageType("RECEIVED");
    receivedMessage.setCreatedAt(now);
    messagingRepository.save(receivedMessage);

    System.out.println(sb); <--- Prints response object to console
    return sb.toString();
}

Answer 1

您可以为此使用jackson 库。

解决方案1：您可以使用ObjectMapper，如下：

将 JSON 映射到 Java 对象的消息类：

public class Message {
 private String originationNumber;
 private String messageBody;

 // public getter and setters methods

}

从 JSON 字符串创建对象：

Message message = null;

ObjectMapper objectMapper = new ObjectMapper();
objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
try {
   message = objectMapper.readValue(payload, Message.class);
} catch (JsonProcessingException e) {
   // Log Or do some action as per need
}

这里message 将具有这些值。 DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES 在这里用于跳过异常，因为 JSON 中还有其他字段，而 Java 类中不存在（因为我们不需要它们）。

解决方案 2：或者，您可以使用同一 Jackson 库中的 JsonNode 并逐个读取节点，如下所示：

ObjectMapper mapper = new ObjectMapper();
JsonNode actualObj = mapper.readTree("{\"originationNumber\":\"***\",\"destinationNumber\":\"***\",\"messageKeyword\":\"KEYWORD_***\",\"messageBody\":\"Answer \",\"previousPublishedMessageId\":\"1slamq6mdpucd8q4i7iabf1sikc629ga253tr6o0\",\"inboundMessageId\":\"88bc02fc-aff3-4277-ac1d-f27b6d3b6abb\"}");

String originationNumber = actualObj.get("originationNumber");
String messageBody = actualObj.get("messageBody");

在这种方法中，您不需要创建Message 类。

Answer 2

可以将json字符串转换成json对象 https://www.javatpoint.com/how-to-convert-string-to-json-object-in-java

String string = "{\"originationNumber\":\"***\",\"destinationNumber\":\"***\",\"messageKeyword\":\"KEYWORD_***\",\"messageBody\":\"Answer \",\"previousPublishedMessageId\":\"1slamq6mdpucd8q4i7iabf1sikc629ga253tr6o0\",\"inboundMessageId\":\"88bc02fc-aff3-4277-ac1d-f27b6d3b6abb\"}";  
JSONObject json = new JSONObject(string);  
System.out.println(json.toString());  
String destinationNumber = json.getString("destinationNumber");  
System.out.println(destinationNumber);

Answer 3

你的 json 喜欢的地方

     {"originationNumber":"***",
    "destinationNumber":"***",
    "messageKeyword":"KEYWORD_***",
    "messageBody":"Answer","previousPublishedMessageId":"1slamq6mdpucd8q4i7iabf1sikc629ga253tr6o0",
    "inboundMessageId":"88bc02fc-aff3-4277-ac1d-f27b6d3b6abb"
    }

喜欢

"key":Value

我认为你的代码会像

receivedMessage.setUserId(userId);
receivedMessage.setOriginationNumber("originationNumber");
receivedMessage.setDestinationNumber("destinationNumber");
receivedMessage.setMessageBody("messageBody");
receivedMessage.setMessageType("RECEIVED");
receivedMessage.setCreatedAt(now);
messagingRepository.save(receivedMessage);