Im using Jersey to build a REST Service and want to return a Collection<String>
as XML.
@GET
@Produces(MediaType.TEXT_XML)
@Path("/directgroups")
public Response getDirectGroupsForUser(@PathParam("userId") String userId) {
try {
Collection<String> result = service.getDirectGroupsForUser(userId, null, true);
// return result; //first try
// return result.toArray(new String[0]); //second try
return Response.ok().type(MediaType.TEXT_XML).entity(result).build(); //third try
} catch (UserServiceException e) {
LOGGER.error(e);
throw new RuntimeException(e.getMessage());
}
}
but my attempts fail with the following exception:
javax.ws.rs.WebApplicationException: com.sun.jersey.api.MessageException: A message body writer for Java class java.util.ArrayList, and Java type class java.util.ArrayList, and MIME media type text/xml was not found
and all results to that exception I found via google dealt with returning text/json instead of text/xml like in my situation.
Can anyone help me? I thought, if I use a Response, that would be my root element in XML and my collection a list of string elements in it..
Use
List<String> list = new ArrayList<String>();
GenericEntity<List<String>> entity = new GenericEntity<List<String>>(list) {};
Response response = Response.ok(entity).build();
The Generic entity wrapper works to get the output when using the Response builder.
Reference
NOTE: Although this answer works, anar's answer is better.
You should try to use a JAXB annotated class to solve your problem. You could change your method to this:
@GET
@Produces(MediaType.TEXT_XML)
@Path("/directgroups")
public Groups getDirectGroupsForUser(@PathParam("userId") String userId) {
try {
Groups groups = new Groups();
groups.getGroup().addAll(service.getDirectGroupsForUser(userId, null, true));
return groups;
} catch (UserServiceException e) {
LOGGER.error(e);
throw new RuntimeException(e.getMessage());
}
}
And then create a JAXB annotated class for your groups. I have included a generated class for you, using the process described in this answer. Here is an example of the documents that it will produce:
<groups>
<group>Group1</group>
</group>Group2</group>
</groups>
And here is the generated class:
package example;
import java.util.ArrayList;
import java.util.List;
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;
/**
* <p>Java class for anonymous complex type.
*
* <p>The following schema fragment specifies the expected content contained within this class.
*
* <pre>
* <complexType>
* <complexContent>
* <restriction base="{http://www.w3.org/2001/XMLSchema}anyType">
* <sequence>
* <element ref="{}group" maxOccurs="unbounded"/>
* </sequence>
* </restriction>
* </complexContent>
* </complexType>
* </pre>
*
*
*/
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(name = "", propOrder = {
"group"
})
@XmlRootElement(name = "groups")
public class Groups {
@XmlElement(required = true)
protected List<String> group;
/**
* Gets the value of the group property.
*
* <p>
* This accessor method returns a reference to the live list,
* not a snapshot. Therefore any modification you make to the
* returned list will be present inside the JAXB object.
* This is why there is not a <CODE>set</CODE> method for the group property.
*
* <p>
* For example, to add a new item, do as follows:
* <pre>
* getGroup().add(newItem);
* </pre>
*
*
* <p>
* Objects of the following type(s) are allowed in the list
* {@link String }
*
*
*/
public List<String> getGroup() {
if (group == null) {
group = new ArrayList<String>();
}
return this.group;
}
}
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