如何避免 json 字符串中的 \" ？

Question

Spring 启动应用程序

在 build.gradle 中：

implementation 'com.google.code.gson:gson:2.7'

这里是 JMS 配置：

import org.springframework.boot.autoconfigure.jms.DefaultJmsListenerContainerFactoryConfigurer;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.jms.config.DefaultJmsListenerContainerFactory;
import org.springframework.jms.config.JmsListenerContainerFactory;
import org.springframework.jms.support.converter.MappingJackson2MessageConverter;
import org.springframework.jms.support.converter.MessageConverter;
import org.springframework.jms.support.converter.MessageType;
@Configuration
@ComponentScan(basePackages = "ru.otus.software_architect.eshop")
public class JMSConfiguration {

    @Bean
    public JmsListenerContainerFactory<?> myFactory(ConnectionFactory connectionFactory,
                                                    DefaultJmsListenerContainerFactoryConfigurer configurer) {
        DefaultJmsListenerContainerFactory factory = new DefaultJmsListenerContainerFactory();
        // This provides all boot's default to this factory, including the message converter
        configurer.configure(factory, connectionFactory);
        // You could still override some of Boot's default if necessary.
        return factory;
    }

    @Bean
    public MessageConverter jacksonJmsMessageConverter() {
        MappingJackson2MessageConverter converter = new MappingJackson2MessageConverter();
        converter.setTargetType(MessageType.TEXT);
        converter.setTypeIdPropertyName("_type");
        return converter;
    }
}

这里我如何向 ActiviveMQ 发送消息：

private void sendMessageToMessageBroker(NotifyActionEnum action, int orderId) {
        JsonObject json = new JsonObject();
        json.addProperty("email", UserService.getCurrentUserName());
        json.addProperty("action", action.name().toLowerCase());
        json.addProperty("orderId", orderId);
        JmsTemplate jmsTemplate = context.getBean(JmsTemplate.class);
        String message = json.toString();
        jmsTemplate.convertAndSend(ESHOP_QUEUE, message);
        logger.info("sendMessageToMessageBroker: success_sent_message_to_MB: " + message);
    }

在日志中：

success_sent_message_to_MB:

{"email":"someemail@email.com","action":"order_update","orderId":14}

不错。

但在我的队列中的 ActiveMQ 上，消息如下所示：

  "{\"email\":\"a_subscriber@mail.ru\",\"action\":\"order_update\",\"orderId\":4,\"createdAt\":\"2020-09-13T11:32:09.976+0300\"}"

这里截图：

然后我开始我的另一个应用程序（消费者）。当尝试从 json 获取日期时它被破坏了：

JsonElement messageJson = GsonUtil.parser.parse(message);
String action = messageJson.getAsJsonObject().get("action").getAsString(); // here broken

我收到错误消息：

Caused by: java.lang.IllegalStateException: Not a JSON Object: "{\"email\":\"a_subscriber@mail.ru\",\"action\":\"order_update\",\"orderId\":4,\"createdAt\":\"2020-09-13T11:32:09.976+0300\"}"

如何避免字符串中的“\”？

我需要排队成为下一个字符串：

{"email":"someemail@email.com","action":"order_update","orderId":14}

Answer 1

尝试使用默认的MessageConverter（即SimpleMessageConverter）并将您的消息作为byte[]发送，例如：

private void sendMessageToMessageBroker(NotifyActionEnum action, int orderId) {
   JsonObject json = new JsonObject();
   json.addProperty("email", UserService.getCurrentUserName());
   json.addProperty("action", action.name().toLowerCase());
   json.addProperty("orderId", orderId);
   JmsTemplate jmsTemplate = context.getBean(JmsTemplate.class);
   String message = json.toString();
   jmsTemplate.convertAndSend(ESHOP_QUEUE, message.getBytes());
   logger.info("sendMessageToMessageBroker: success_sent_message_to_MB: " + message);
}

当您以byte[] 发送消息时，SimpleMessageConverter 会将其转换为javax.jms.BytesMessage。当您的消费者收到消息时，它可以将byte[] 转换为String，如下所示：

String messageAsString;
if (message instanceof BytesMessage) {
   BytesMessage bytesMessage = (BytesMessage) message;
   byte[] buffer = new byte[(int) bytesMessage.getBodyLength()];
   bytesMessage.readBytes(buffer);   
   messageAsString = new String(buffer);
}
JsonElement messageJson = GsonUtil.parser.parse(messageAsString);
String action = messageJson.getAsJsonObject().get("action").getAsString();

我相信以byte[] 的形式发送消息将避免任何不必要的转义。

Answer 2

我使用urlEncode/decode向ActiveMQ发送消息

在我的控制器中：

private String publishToMessageBroker(NotifyActionEnum action, int orderId) {
        logger.info("publishToMessageBroker:");
        JsonObject json = new JsonObject();
        json.addProperty("email", UserService.getCurrentUserName());
        json.addProperty("action", action.name().toLowerCase());
        json.addProperty("orderId", orderId);
        json.addProperty("createdAt", DateUtil.date2String(new Date(), DateUtil.JSON_DATE_FORMAT));
        String message = json.toString();
        String urlEncodeMessage = StringUtll.urlEncode(message);
        jmsTemplate.convertAndSend(ESHOP_QUEUE, urlEncodeMessage);
        logger.info("publishToMessageBroker: success_sent_message_to_MB: " + message);
        return "Message was success published on Message Broker!"; // can use as response
}

现在在 ActiveMQ 中，消息如下所示：

"%7B%22email%22%3A%22myemail%40mail.com%22%2C%22action%22%3A%22order_delete%22%2C%22orderId%22%3A6%2C%22createdAt%22%3A%222020-09-19T12%3A20%3A57.844%2B0300%22%7D"

现在在消息接收器中我解码消息

 @JmsListener(destination = ESHOP_QUEUE)
    public void receiveMessage(String urlEncodeMessage) {
        try {
            String urlDecodeMessage = StringUtil.urlDecode(urlEncodeMessage);
            String pureDecodeMessage = StringUtil.removeFirstAndLastQuotes(urlDecodeMessage);
            JsonElement messageJson = GsonUtil.parser.parse(pureDecodeMessage);

现在工作正常。没有像 "" 这样的 mor 转义符号。

url解码后我得到纯json：

"{"email":"myemail@mail.com","action":"order_delete","orderId":6,"createdAt":"2020-09-19T12:20:57.844+0300"}"