无法提取响应：没有找到适合响应类型的 HttpMessageConverter

Question

我是 spring 集成的新手，并且在 spring 集成 http 模块中工作以满足我的项目需求。我作为 http 客户端从出站网关发送请求。 我正在尝试向服务器发起请求，服务器应该使用我的设置值向我返回消息有效负载。我正在将对象转换为 JSON 用于发送到服务器 我正在从客户端（HttpClientDemo）向服务器端的入站网关发送请求，如下所示。为此，我将我的对象转换为 JSON，然后在客户端将 JSON 字符串转换为对象，在那里执行一些简单的操作并将其发送回客户端（HttpClientDemo），但在此之前，我遇到了与HttpMessageConverter如下：

Exception in thread "main" org.springframework.web.client.RestClientException: Could not extract response: no suitable HttpMessageConverter found for response type [class com.mycompany.MyChannel.model.FFSampleResponseHttp] and content type [text/plain;charset=UTF-8]
    at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:108)
    at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:784)
    at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:769)
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:549)
    at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:517)
    at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:462)
    at org.springframework.integration.http.outbound.HttpRequestExecutingMessageHandler.handleRequestMessage(HttpRequestExecutingMessageHandler.java:421)
    at org.springframework.integration.handler.AbstractReplyProducingMessageHandler.handleMessageInternal(AbstractReplyProducingMessageHandler.java:170)
    at org.springframework.integration.handler.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:78)
    at org.springframework.integration.dispatcher.AbstractDispatcher.tryOptimizedDispatch(AbstractDispatcher.java:116)
    at org.springframework.integration.dispatcher.UnicastingDispatcher.doDispatch(UnicastingDispatcher.java:101)
    at org.springframework.integration.dispatcher.UnicastingDispatcher.dispatch(UnicastingDispatcher.java:97)
    at org.springframework.integration.channel.AbstractSubscribablMyChannel.doSend(AbstractSubscribablMyChannel.java:77)
    at org.springframework.integration.channel.AbstractMessagMyChannel.send(AbstractMessagMyChannel.java:255)
    at org.springframework.integration.channel.AbstractMessagMyChannel.send(AbstractMessagMyChannel.java:223)
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:114)
    at org.springframework.messaging.core.GenericMessagingTemplate.doSend(GenericMessagingTemplate.java:44)
    at org.springframework.messaging.core.AbstractMessageSendingTemplate.send(AbstractMessageSendingTemplate.java:93)

请在下面找到相关代码：

客户端代码： HttpClientDemo.java

public class HttpClientDemo {

    private static Logger logger = Logger.getLogger(HttpClientDemo.class);
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("/META-INF/spring/integration/http-outbound-config.xml");
RequestGateway requestGateway = context.getBean("requestGateway", RequestGateway.class);        
        FFSampleRequestHttp FFSampleRequesthttp = new FFSampleRequestHttp();
        FFSampleRequesthttp.setMyChannelID("1");
        FFSampleRequesthttp.setMyNumber("88");
        FFSampleRequesthttp.setReferenceID("9I");
        FFSampleRequesthttp.setTemplateType(1);
        FFSampleRequesthttp.setTimestamp("today");
        FFSampleResponseHttp  reply = requestGateway.FFSampleResponsegatway(FFSampleRequesthttp);
            logger.info("Replied with: " + reply);
    }

}

我的请求网关如下：RequestGateway.java

public interface RequestGateway {


    FFSampleResponseHttp FFSampleResponsegatway(FFSampleRequestHttp request);

}

http-outbound-config.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:int="http://www.springframework.org/schema/integration"
    xmlns:int-http="http://www.springframework.org/schema/integration/http"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/integration http://www.springframework.org/schema/integration/spring-integration.xsd
        http://www.springframework.org/schema/integration/http http://www.springframework.org/schema/integration/http/spring-integration-http.xsd">

    <int:gateway id="requestGateway" 
                 service-interface="com.mycompany.MyChannel.Common.RequestGateway"
                 default-request-channel="requestChannel"/>

    <int:channel id="requestChannel"/>
    <int:channel id="requestChannel1"/>


<!--    com.mycompany.MyChannel.model.FFSampleResponseHttp -->

    <int-http:outbound-gateway request-channel="requestChannel1" reply-channel="replyChannel1" url="http://localhost:8080/MyChannel_prj-1.0.0.BUILD-SNAPSHOT/receiveGateway"  http-method="POST"  extract-request-payload="true" expected-response-type="com.mycompany.MyChannel.model.FFSampleResponseHttp"/>

   <int:object-to-json-transformer  input-channel="requestChannel" output-channel="requestChannel1" content-type="application/json"  result-type="STRING"/>



   <bean id="FFSampleRequestHttp" class="com.mycompany.MyChannel.model.FFSampleRequestHttp"></bean>


</beans>

Web.xml

<?xml version="1.0" encoding="ISO-8859-1" standalone="no"?>
<web-app xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.4" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">


<servlet>
    <servlet-name>MyChannel-http</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>/WEB-INF/servlet-config.xml</param-value>
    </init-param>
    <load-on-startup>2</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>MyChannel-http</servlet-name>
    <url-pattern>/receiveGateway</url-pattern>
   </servlet-mapping>


    <welcome-file-list>
        <welcome-file>index.html</welcome-file>
    </welcome-file-list>

</web-app>

servlet-config.xml

    <int:channel id="receivMyChannel"/>

<int-http:inbound-gateway request-channel="receivMyChannel" path="/receiveGateway" supported-methods="POST"/>

    <int:service-activator input-channel="receivMyChannel">
        <bean class="com.mycompany.MyChannel.serviceImpl.FFSampleHttpImpl">
        <constructor-arg ref = "FFSampleRequestHttp"></constructor-arg>
        </bean>
        </int:service-activator>


     <bean id="FFSampleRequestHttp" class="com.mycompany.MyChannel.model.FFSampleRequestHttp"></bean>
     <bean id="FFSampleResponseHttp" class="com.mycompany.MyChannel.model.FFSampleResponseHttp"></bean>

    </beans> 



public class FFSampleHttpImpl{

    private static org.apache.log4j.Logger log = Logger
            .getLogger(FFSampleImpl.class);

    @Autowired
    FFSampleRequestHttp request;
    public FFSampleHttpImpl() {
    }

    public FFSampleHttpImpl(FFSampleRequestHttp request) {
        super();
        this.request = request;
    }





    public String issueResponseFor(String str) throws JsonParseException, JsonMappingException, IOException {

        ObjectMapper mapper = new ObjectMapper();

        FFSampleRequestHttp FFSampleRequestHttp = mapper.readValue(new String(str), FFSampleRequestHttp.class);

        FFSampleRequestHttp.setReferenceID("Hi My Number");

        String  strs = new String();

        strs = mapper.writeValueAsString(FFSampleRequestHttp);

            return strs;

        }

}

FFSampleRequestHttp.java

public class FFSampleRequestHttp {
    protected String MyNumber;  
    protected String referenceID;   
    protected String myChannelID;
    protected String timestamp;
    protected int templateType;
    public String getMyNumber() {
        return MyNumber;
    }
    public void setMyNumber(String MyNumber) {
        this.MyNumber = MyNumber;
    }
    public String getReferenceID() {
        return referenceID;
    }
    public void setReferenceID(String referenceID) {
        this.referenceID = referenceID;
    }
    public String getMyChannelID() {
        return myChannelID;
    }
    public void setMyChannelID(String myChannelID) {
        this.myChannelID = myChannelID;
    }
    public String getTimestamp() {
        return timestamp;
    }
    public void setTimestamp(String timestamp) {
        this.timestamp = timestamp;
    }
    public int getTemplateType() {
        return templateType;
    }
    public void setTemplateType(int templateType) {
        this.templateType = templateType;
    }
    }

FFSampleResponseHttp.java

public class FFSampleResponseHttp {
    protected String MyNumber;
    protected String referenceID;
    protected String myChannelID;
    protected String timestamp;
    protected int templateType;

    public String getMyNumber() {
        return MyNumber;
    }
    public void setMyNumber(String MyNumber) {
        this.MyNumber = MyNumber;
    }
    public String getReferenceID() {
        return referenceID;
    }
    public void setReferenceID(String referenceID) {
        this.referenceID = referenceID;
    }
    public String getMyChannelID() {
        return myChannelID;
    }
    public void setMyChannelID(String myChannelID) {
        this.myChannelID = myChannelID;
    }
    public String getTimestamp() {
        return timestamp;
    }
    public void setTimestamp(String timestamp) {
        this.timestamp = timestamp;
    }
    public int getTemplateType() {
        return templateType;
    }
    public void setTemplateType(int templateType) {
        this.templateType = templateType;
    }
    }

当我运行上面的代码时，我得到以下错误：

16:55:46.843 [main] DEBUG o.s.web.client.RestTemplate - Writing [{"MyNumber":"88","referenceID":"9I","myChannelID":"1","timestamp":"today","templateType":1}] as "text/plain;charset=UTF-8" using [org.springframework.http.converter.StringHttpMessageConverter@7d31a3e2]
16:55:46.988 [main] DEBUG o.s.web.client.RestTemplate - POST request for "http://localhost:8080/MyChannel_prj-1.0.0.BUILD-SNAPSHOT/receiveGateway" resulted in 200 (OK)
Exception in thread "main" org.springframework.web.client.RestClientException: Could not extract response: no suitable HttpMessageConverter found for response type [class com.mycompany.MyChannel.model.FFSampleResponseHttp] and content type [text/plain;charset=UTF-8]
    at org.springframework.web.client.HttpMessageConverterExtractor. 

我使用了spring集成基本示例代码供参考。 请提供您的意见。我还尝试在配置文件中使用带有 JSON 到对象转换器的 spring 对象映射器，但我也遇到了 HttpMessageConverter 的类似问题。 请帮助我提供宝贵的意见/建议，如果我们对 Spring 集成 http 对象映射器有任何限制，请告诉我。

---

嗨，Artem， 感谢您的回复。我仍然面临下面提到的一些挑战。根据您的建议，我已对配置文件进行了更改。但在使用 Jackson2JsonObjectMapper 时遇到问题，需要您的进一步帮助。请在下面找到问题描述。

我已经对我的文件进行了更改，现在文件如下所示： 我的 Servlet-Config.xml 文件内容如下：

<int:channel id="channel1" /> 
<int:channel id="channel2" /> 
<int:channel id="channel3" /> 
<int-http:inbound-gateway request-channel="channel1" supported-methods="POST" path="/receiveGateway" /> 
- <int:service-activator input-channel="channel2"> 
- <bean class="com.myCompany.myChannel.serviceImpl.FFSampleHttpImpl"> 
<constructor-arg ref="ffSampleRequestHttp" /> 
</bean> 
</int:service-activator> 

<int:json-to-object-transformer input-channel="channel1" output-channel="channel2" type="com.myCompany.myChannel.model.FFSampleRequestHttp" object-mapper="jackson2JsonObjectMapper" /> 

<bean id="jackson2JsonObjectMapper" class="org.springframework.integration.support.json.Jackson2JsonObjectMapper" /> 
<bean id="ffSampleRequestHttp" class="com.myCompany.myChannel.model.FFSampleRequestHttp" /> 
<bean id="ffSampleResponseHttp" class="com.myCompany.myChannel.model.FFSampleResponseHttp" /> 
</beans>

出站文件配置（负责向服务器发送消息的文件）：

<int:gateway id="requestGateway" service-interface="com.myCompany.myChannel.Common.RequestGateway" default-request-channel="requestChannel" /> 
  <int:channel id="requestChannel" /> 
  <int:channel id="requestChannel1" /> 
  <int:object-to-json-transformer input-channel="requestChannel" output-channel="requestChannel1" content-type="application/json" /> 
  <int-http:outbound-gateway request-channel="requestChannel1" reply-channel="channel4" url="http://localhost:8080/myChannel_prj-1.0.0.BUILD-SNAPSHOT/http/receiveGateway" http-method="POST" /> 
  <bean id="FFSampleRequestHttp" class="com.myCompany.myChannel.model.FFSampleRequestHttp" /> 
  <int:json-to-object-transformer input-channel="channel4" output-channel="requestChannel" type="com.myCompany.myChannel.model.FFSampleResponseHttp" object-mapper="jackson2JsonObjectMapper" /> 
  <bean id="jackson2JsonObjectMapper" class="org.springframework.integration.support.json.Jackson2JsonObjectMapper" /> 
  </beans>

我的 impl 类方法如下：

public  FfSampleResponseHttp issueResponseFor(FfSampleRequestHttp request) {

        FfSampleResponseHttp ffSampleResponse2 = new FfSampleResponseHttp();

        ffSampleResponse2.setCifNumber("Yappi I am in the method");
        log.info("issueResponseFor(FfSampleRequesthttp request)");

        return ffSampleResponse2;

    }

我可以从客户端调用我的服务方法 issueResponseFor 存在于服务器端，但是当它进一步处理时：

Caused by: java.lang.IllegalArgumentException: 'json' argument must be an instance of: [class java.lang.String, class [B, class java.io.File, class java.net.URL, class java.io.InputStream, class java.io.Reader]
       at org.springframework.integration.support.json.Jackson2JsonObjectMapper.fromJson(Jackson2JsonObjectMapper.java:93)
       at org.springframework.integration.support.json.Jackson2JsonObjectMapper.fromJson(Jackson2JsonObjectMapper.java:44)
       at org.springframework.integration.support.json.AbstractJacksonJsonObjectMapper.fromJson(AbstractJacksonJsonObjectMapper.java:55)
       at org.springframework.integration.json.JsonToObjectTransformer.doTransform(JsonToObjectTransformer.java:78)
       at org.springframework.integration.transformer.AbstractTransformer.transform(AbstractTransformer.java:33)
       ... 54 more

在成功漫游我的服务方法后，我在调试时验证了有效负载主体在响应时在 Jackson2JsonObjectMapper.fromJson(...) 的参数中的 json 对象中变为空白。我无法理解我在哪里做错了。请提供您的帮助/意见。 再次让我知道我是否在我的配置文件中再次丢失了某些内容。非常感谢您的支持。

Answer 1

由于您只返回到客户端String 及其content type == 'text/plain'，因此默认转换器没有任何机会确定如何将String 响应转换为FFSampleResponseHttp 对象。

修复它的简单方法：

• 从<int-http:outbound-gateway> 中删除expected-response-type
• 添加到replyChannel1 <json-to-object-transformer>

否则您应该编写自己的HttpMessageConverter 以将字符串转换为适当的对象。

要使其与MappingJackson2HttpMessageConverter（默认转换器之一）和您的expected-response-type 一起使用，您应该使用content type = 'application/json' 发送回复。

如果有需要，只需在您的<service-activator> 之后添加<header-enricher>，然后再回复<int-http:inbound-gateway>。

因此，选择哪种解决方案取决于您，但由于与默认配置不一致，您当前的状态不起作用。

更新

好的。由于您将服务器更改为将 FfSampleResponseHttp 对象作为 HTTP 响应而不是字符串返回，因此只需在发送 HTTP 响应之前添加 contentType = 'application/json' 标头，MappingJackson2HttpMessageConverter 将为您完成这些工作 - 您的对象将被转换为 JSON 和带有正确的contentType 标头。

从客户端你应该回到expected-response-type="com.mycompany.MyChannel.model.FFSampleResponseHttp" 和MappingJackson2HttpMessageConverter 应该再次为你做这些事情。

当然你应该在<int-http:outbound-gateway>之后从你的消息流中删除<json-to-object-transformer>。

Answer 2

public class Application {

    private static List<HttpMessageConverter<?>> getMessageConverters() {
        List<HttpMessageConverter<?>> converters = new ArrayList<HttpMessageConverter<?>>();
        converters.add(new MappingJacksonHttpMessageConverter());
        return converters;
    }   

    public static void main(String[] args) {
        RestTemplate restTemplate = new RestTemplate();

        restTemplate.setMessageConverters(getMessageConverters());
        HttpHeaders headers = new HttpHeaders();
        headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
        HttpEntity<String> entity = new HttpEntity<String>(headers);
        //Page page = restTemplate.getForObject("http://graph.facebook.com/pivotalsoftware", Page.class);

        ResponseEntity<Page> response = 
                  restTemplate.exchange("http://graph.facebook.com/skbh86", HttpMethod.GET, entity, Page.class, "1");
        Page page = response.getBody();
        System.out.println("Name:    " + page.getId());
        System.out.println("About:   " + page.getFirst_name());
        System.out.println("Phone:   " + page.getLast_name());
        System.out.println("Website: " + page.getMiddle_name());
        System.out.println("Website: " + page.getName());
    }
}

Answer 3

这是一个简单的解决方案

尝试添加此依赖项

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.8.3</version>
</dependency>

Answer 4

正如 Artem Bilan 所说，出现此问题是因为 MappingJackson2HttpMessageConverter 仅支持使用 application/json 内容类型的响应。如果您不能更改服务器代码，但可以更改客户端代码（我有这种情况），您可以使用拦截器更改内容类型标头：

restTemplate.getInterceptors().add((request, body, execution) -> {
            ClientHttpResponse response = execution.execute(request,body);
            response.getHeaders().setContentType(MediaType.APPLICATION_JSON);
            return response;
        });