你在这里的问题是你只使用原始的 java.util.ArrayList 而你最终只得到 ArrayList>，而不是 ArrayList>.

试试这个技巧:

type="com.that.service.service.test.ApplicationTestDomain[]"

总之，我们不能为 Class 提供通用规范.

但是使用该数组技巧，当框架将 Message 应用到您的服务方法的参数时，应该会自动从 Array 转换为 Collection.>

从另一端提供expected-response-type-expression，可以返回ParameterizedTypeReference>.

这里有一个技巧可以让他知道你想要的类型:

<int:header name="expectedResponseType"><int-groovy:script><![CDATA[new org.springframework.core.ParameterizedTypeReference>() {}]]></int-groovy:script></int:header></int:header-enricher><int-http:outbound-gateway request-channel="applicationConfigurationRequest"回复通道 =testJsonToObjectChannel"url="http://localhost:8080/testapplication/services/application/testService"http-method="GET"expected-response-type-expression="headers.expectedResponseType"/>

当然，有了这个，您就可以允许 RestTemplate 使用 Jackson 将响应转换为所需的值.从这里开始，没有更多理由使用 ，因为您已经有了 POJO 列表.

We are returning an array of objects from a service (http outbound gateway) in json format and we need it serialized back into an array of objects/POJOS. First we tried simply serializing the POJO without any array lists by setting the XML configuration to

<int:json-to-object-transformer input-channel="testJsonToObjectChannel"
            output-channel="testChannel" type="com.that.service.service.test.ApplicationTestDomain" />

and had both the transformer and the http outbound gateway return the same object. However after converting it to an array of "ApplicationTestDomain" POJOs we are getting the error mentioned in the stack trace where it notably mentions

"No converter found capable of converting from type java.util.ArrayList<?> to type com.that.service.service.test.ApplicationTestDomain"

We also tried a simple array of strings and they were succesfully serialized and deserialzed as well, the issue only comes up when we try to serialize and deserialize an array of objects.

Any idea on what needs to be done so that can be resolved

The following is the service which returns the array list

@Service("applicationTestService")
public class ApplicationTestService {

    private static Logger logger = Logger.getLogger(ApplicationTestService.class);

    public ArrayList<ApplicationTestDomain> getTestThatData(Message<?> inMessage){
        ArrayList<ApplicationTestDomain> testData = new ArrayList<ApplicationTestDomain>();

        ApplicationTestDomain testDomain = new ApplicationTestDomain();
        testDomain.setId(1L);
        testDomain.setTotalPrice(100.00D);
        testDomain.setTotalTaxes(70.00D);
        testDomain.setTotalAll(70D);

        testData.add(testDomain);

        return testData;
    }

}

The following is the service which receives the array list

@MessageEndpoint("applicationDataTransformer")
public class ApplicationTransformer {

    public ApplicationResponse transformData(ArrayList<ApplicationTestDomain> response) {
        return new ApplicationResponse();
    }
}

The following is the xml configuration

<int-http:outbound-gateway request-channel="applicationConfigurationRequest" 
                           reply-channel="testJsonToObjectChannel"
                           url="http://localhost:8080/testapplication/services/application/testService"
                           http-method="GET"
                           expected-response-type="java.lang.String"/>


<int:json-to-object-transformer input-channel="testJsonToObjectChannel"
        output-channel="testChannel" type="java.util.ArrayList" />

<int:transformer input-channel="testChannel"
    ref="applicationDataTransformer"
    method="transformData"
    output-channel="applicationConfigurationResponse"/>         

The following is the exception stack trace

at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:52)
    at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:608)
    at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:543)
    at java.lang.Thread.run(Unknown Source)
Caused by: org.springframework.messaging.MessageHandlingException: org.springframework.expression.AccessException: Problem invoking method: public com.that.domain.service.hotelavailability.HotelAvailabilityResponse com.that.transformer.service.ApplicationTransformer.transformData(java.util.ArrayList)
    at org.springframework.integration.handler.MethodInvokingMessageProcessor.processMessage(MethodInvokingMessageProcessor.java:78)
    at org.springframework.integration.transformer.AbstractMessageProcessingTransformer.transform(AbstractMessageProcessingTransformer.java:64)
    at org.springframework.integration.transformer.MessageTransformingHandler.handleRequestMessage(MessageTransformingHandler.java:68)
    ... 83 more
Caused by: org.springframework.expression.AccessException: Problem invoking method: public com.that.domain.service.hotelavailability.HotelAvailabilityResponse com.that.transformer.service.ApplicationTransformer.transformData(java.util.ArrayList)
    at org.springframework.expression.spel.support.ReflectiveMethodExecutor.execute(ReflectiveMethodExecutor.java:67)
    at org.springframework.expression.spel.ast.MethodReference.getValueInternal(MethodReference.java:122)
    at org.springframework.expression.spel.ast.MethodReference.access$000(MethodReference.java:44)
    at org.springframework.expression.spel.ast.MethodReference$MethodValueRef.getValue(MethodReference.java:258)
    at org.springframework.expression.spel.ast.CompoundExpression.getValueInternal(CompoundExpression.java:84)
    at org.springframework.expression.spel.ast.SpelNodeImpl.getTypedValue(SpelNodeImpl.java:114)
    at org.springframework.expression.spel.standard.SpelExpression.getValue(SpelExpression.java:111)
    at org.springframework.integration.util.AbstractExpressionEvaluator.evaluateExpression(AbstractExpressionEvaluator.java:159)
    at org.springframework.integration.util.MessagingMethodInvokerHelper.processInternal(MessagingMethodInvokerHelper.java:268)
    at org.springframework.integration.util.MessagingMethodInvokerHelper.process(MessagingMethodInvokerHelper.java:142)
    at org.springframework.integration.handler.MethodInvokingMessageProcessor.processMessage(MethodInvokingMessageProcessor.java:75)
    ... 85 more
Caused by: org.springframework.core.convert.ConversionFailedException: Failed to convert from type java.util.ArrayList<?> to type java.util.ArrayList<com.that.service.service.test.ApplicationTestDomain> for value '[{id=1, totalPrice=100.0, totalTaxes=70.0, totalAll=70.0}]'; nested exception is org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type java.util.ArrayList<?> to type com.that.service.service.test.ApplicationTestDomain
    at org.springframework.core.convert.support.ConversionUtils.invokeConverter(ConversionUtils.java:41)
    at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:174)
    at org.springframework.integration.util.BeanFactoryTypeConverter.convertValue(BeanFactoryTypeConverter.java:123)
    at org.springframework.expression.spel.support.ReflectionHelper.convertArguments(ReflectionHelper.java:240)
    at org.springframework.expression.spel.support.ReflectiveMethodExecutor.execute(ReflectiveMethodExecutor.java:57)
    ... 95 more
Caused by: org.springframework.core.convert.ConverterNotFoundException: No converter found capable of converting from type java.util.ArrayList<?> to type com.that.service.service.test.ApplicationTestDomain
    at org.springframework.core.convert.support.GenericConversionService.handleConverterNotFound(GenericConversionService.java:291)
    at org.springframework.core.convert.support.GenericConversionService.convert(GenericConversionService.java:177)
    at org.springframework.core.convert.support.CollectionToCollectionConverter.convert(CollectionToCollectionConverter.java:85)
    at org.springframework.core.convert.support.ConversionUtils.invokeConverter(ConversionUtils.java:35)
    ... 99 more

Regards, MilindaD

Your issues here that you just use raw java.util.ArrayList and you end up just with ArrayList<LinkedHashMap<String, Object>>, rather than ArrayList<LinkedHashMap<String, ApplicationTestDomain>>.

Try this trick:

type="com.that.service.service.test.ApplicationTestDomain[]"

The general stop here that we can't provide Class with generic specification.

But with that array trick there should automatic conversion from Array to Collection when Framework appies Message to arguments of your service method.

From other side <int-http:outbound-gateway> provides expected-response-type-expression, which can return ParameterizedTypeReference<?>.

Here is a trick how to let him know about your desired type:

<int:header-enricher>
        <int:header name="expectedResponseType">
            <int-groovy:script>
                <![CDATA[
                    new org.springframework.core.ParameterizedTypeReference<List<com.that.service.service.test.ApplicationTestDomain>>() {}
                ]]>
            </int-groovy:script>       
        </int:header>
</int:header-enricher>

<int-http:outbound-gateway request-channel="applicationConfigurationRequest" 
                       reply-channel="testJsonToObjectChannel"
                       url="http://localhost:8080/testapplication/services/application/testService"
                       http-method="GET"
                       expected-response-type-expression="headers.expectedResponseType"/>

Having this you allow to RestTemplate to convert response to the desired value using Jackson, of course. And from here there is no more reason to use <int:json-to-object-transformer>, because you already have your List of POJOs.