This document describes a Mule flow that uses a custom transformer to convert an XML payload to JSON. The flow contains an inbound file endpoint that reads an XML file, a custom transformer java class that performs the conversion, and an outbound file endpoint that writes the JSON output to a new file. The custom transformer uses Jackson libraries to parse the XML into a List and then convert it to a JSON string. The example shows how to build and test the flow to successfully transform and output the XML payload as JSON.

1. By Anirban Sen Chowdhary

4. .

5. Here I will show you how ……

6. Let us consider we have a following Mule flow :-
Now you can see in the above flow the inbound endpoint will pic
a file that contains XML content from a location and put it into
another location and the outbound file will contain it’s
corresponding JSON content.
You can also see a custom transformer in the middle which is
responsible for this XML payload conversion to JSON directly.

7. Now, let’s check the code for this flow :-
<flow name="CustomXMLToJSONTransformer"
doc:name="CustomXMLToJSONTransformer">
<file:inbound-endpoint path="E:backuptest" responseTimeout="10000"
doc:name="File">
<file:filename-regex-filter pattern="xmlFile.txt" caseSensitive="false"/>
</file:inbound-endpoint>
<file:file-to-string-transformer doc:name="File to String"/>
<custom-transformer class="CustomXMLToJSONTransformer"
doc:name="XmlToJson"/>
<logger message="#[message.payload]" level="INFO" doc:name="Logger" />
<file:outbound-endpoint path="E:backuptestnewfolder"
outputPattern="jsonFile.txt" responseTimeout="10000" doc:name="File" />
</flow>
As you can see the file xmlFile.txt contains XML content that will be
converted directly into JSON by the custom-transformer into a file
jsonFile.txt

8. Now let’s check the XML content of file xmlFile.txt :-
So, the above is the XML content we need to convert using our
custom transformer into a corresponding JSON

9. So our custom transformer java class is the following :-
public class CustomXMLToJSONTransformer extends AbstractMessageTransformer implements
DiscoverableTransformer {
public Object transformMessage(MuleMessage message, String outputEncoding)
throws TransformerException {
try {
String xml = (String) message.getPayload();
XmlMapper xmlMapper = new XmlMapper();
List entries = xmlMapper.readValue(xml, List.class);
ObjectMapper jsonMapper = new ObjectMapper();
String json = jsonMapper.writeValueAsString(entries);
return json;
} catch (Exception e) {
System.out.println("Error: " + e);
e.printStackTrace();
}
return null;
}
@Override
public int getPriorityWeighting() {
return 0;
}
@Override
public void setPriorityWeighting(int weighting) {
}
}

10. Now let’s test our application . We will see the following in our Mule console
:-
You can see the payload is transformed into JSON and has been
dispatched to location E:backuptestnewfolder with file name
jsonFile.txt

11. Now if we open the file jsonFile.txt from location
E:backuptestnewfolder we will get our JSON content as
following
You can see you have generated the JSON for the XML directly just
using a simple custom transformer component

12. Hope you enjoyed the simple yet an amazing trick in Mule