Resttemplate : HttpMessageNotWritableException: No serializer found for class java.io.ByteArrayInputStream - spring-integration

Question

Using Spring Integration I upload a file via HTTP POST and route it to a service activator.
In the service activator, I make a call using RestTemplate to another server where to dump the file but I can't figure out why I get the following error for the following code:
What I don't understand is why I get the exception below when I call RestTemplate.exchange()
at pdi.integration.MultipartReceiver.printMultiPartContent(MultipartReceiver.java:41)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
xml-config
<?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/integration http://www.springframework.org/schema/integration/spring-integration.xsd
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/integration/http http://www.springframework.org/schema/integration/http/spring-integration-http.xsd">
<bean id="byteArrayHttpMessageConverter"
class="org.springframework.http.converter.ByteArrayHttpMessageConverter">
</bean>
<bean id="formHttpMessageConverter"
class="org.springframework.http.converter.FormHttpMessageConverter">
</bean>
<bean id="multipartResolver"
class="org.springframework.web.multipart.commons.CommonsMultipartResolver"/>
<bean id="headerMapper" class="org.springframework.integration.http.support.DefaultHttpHeaderMapper">
<property name="inboundHeaderNames" value="*"/>
<property name="outboundHeaderNames" value="*"/>
<property name="userDefinedHeaderPrefix" value=""/>
</bean>
<int:channel id="http.frontend.rx"/>
<int:channel id="http.frontend.tx"/>
<int:channel id="http.backend.mysql.rx"/>
<int:channel id="http.backend.mysql.tx"/>
<int:channel id="http.backend.mongo.rx"/>
<int:channel id="http.backend.mongo.tx"/>
<int:channel id="http.backend.file.tx"/>
<int-http:inbound-gateway
id="frontEndToMySQLXX"
request-channel="http.frontend.rx"
reply-channel="http.frontend.tx"
header-mapper="headerMapper"
path="/gateway"
supported-methods="GET,POST,PUT,DELETE"/>
<int:router id="frontEndRouter" input-channel="http.frontend.rx" expression="headers.service">
<int:mapping value="json" channel="http.backend.mysql.tx" />
<int:mapping value="file" channel="http.backend.mongo.tx" />
<int:mapping value="upload" channel="http.backend.file.tx" />
</int:router>
<!-- removed : message-converters="formHttpMessageConverter,byteArrayHttpMessageConverter" -->
<int-http:outbound-gateway
id="toMongoDB"
request-channel="http.backend.mongo.tx"
reply-channel="http.backend.mongo.rx"
url="http://localhost:5050/api/{path}"
http-method-expression="headers.http_requestMethod"
header-mapper="headerMapper"
expected-response-type="byte[]">
<int-http:uri-variable name="path" expression="headers['urlpath']"/>
</int-http:outbound-gateway>
<int-http:outbound-gateway
id="toMySQLDB"
request-channel="http.backend.mysql.tx"
reply-channel="http.backend.mysql.rx"
url="http://localhost:7070/api/{path}"
http-method-expression="headers.http_requestMethod"
expected-response-type="java.lang.String"
charset="UTF-8">
<int-http:uri-variable name="path" expression="headers['urlpath']"/>
</int-http:outbound-gateway>
<int:service-activator
id="MySQLToFrontEnd"
input-channel="http.backend.mysql.rx"
output-channel="http.frontend.tx"
ref="messageService"
method="printContent">
</int:service-activator>
<int:service-activator
id="MongoToFrontEnd"
input-channel="http.backend.file.tx"
output-channel="http.frontend.tx"
ref="multipartReceiver"
method="printMultiPartContent">
</int:service-activator>
</beans>
bean used by service activator
#Component
public class MultipartReceiver {
public void printMultiPartContent(LinkedMultiValueMap<String, Object> multipartRequest){
System.out.println("### Successfully received multipart request ###");
for (String elementName : multipartRequest.keySet()) {
if (elementName.equals("file")){
System.out.println("\t" + elementName + " - as UploadedMultipartFile: " +
((UploadedMultipartFile) multipartRequest
.getFirst("file")).getOriginalFilename());
}
}
RestTemplate template = new RestTemplate();
String uri = "http://localhost:5050/api/upload";
MultiValueMap map = new LinkedMultiValueMap<String,Object>();
map.add("file", multipartRequest.getFirst("file"));
HttpHeaders headers = new HttpHeaders();
headers.set("Content-Type", "multipart/form-data");
HttpEntity request = new HttpEntity(map, headers);
ResponseEntity<byte[]> response = template.exchange(uri, HttpMethod.POST, request, byte[].class);
}
}
stacktrace :: http://pastebin.com/5Wa9VaRb
working code ::
public void printMultiPartContent(LinkedMultiValueMap<String, Object> multipartRequest) throws IOException {
final String filename = ((UploadedMultipartFile) multipartRequest.getFirst("file")).getOriginalFilename();
RestTemplate template = new RestTemplate();
MultiValueMap<String, Object> multipartMap = new LinkedMultiValueMap<String, Object>();
multipartMap.add("name", filename);
multipartMap.add("filename", filename);
byte[] bytes = ((UploadedMultipartFile) multipartRequest.getFirst("file")).getBytes();
ByteArrayResource contentsAsResource = new ByteArrayResource(bytes){
public String getFilename(){
return filename;
}
};
multipartMap.add("file", contentsAsResource);
String result = template.postForObject("http://localhost:5050/api/upload", multipartMap, String.class);
System.out.println(result);
}

Answer 1

The problem is you are passing the complete UploadedMultipartFile object to the RestTemplate. Jackson is trying to serialize the object, including the inputStream property, which it cannot.
It appears you need to extract the file contents
byte[] bytes ((UploadedMultipartFile) multipartRequest.getFirst("file")).getBytes();
And set the content type to the UploadedMultipartFile.getContentType().