JAX-RS gives status code 500 for GET operation for XML type response

Question

I have just begun to learn RESTful services and this is the issue I have been facing recently. When I run the application to GET an XML type response, I get status code 500 and I don't see any stack trace for this as well. Am I missing anything in the dependency list ? Please help me figure this.

Here is the entity class :

import java.util.Date;


import jakarta.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Message {

    private int id;
    private String message;
    private String author;
    private Date date;

    public Message() {}

    public Message(int id, String message, String author) {
        super();
        this.id = id;
        this.message = message;
        this.author = author;
        this.date = new Date();
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public Date getDate() {
        return date;
    }

    public void setDate(Date date) {
        this.date = date;
    }

    @Override
    public String toString() {
        return "Message [id=" + id + ", message=" + message + ", author=" + author + ", date=" + date + "]";
    }
}

And then I have my service class : MessageService.java :

import java.util.ArrayList;
import java.util.List;

import org.aravind.restful.messenger.model.Message;

public class MessageService {

    public List<Message> getMessages()
    {
        Message m1 = new Message(1,"Hello World!","aravind");
        Message m2 = new Message(2,"First step towards the goal!","aravind");
        List <Message> messageList = new ArrayList<Message>();
        messageList.add(m1);
        messageList.add(m2);
        return messageList;
    }

}

And then I have the resource class : MessengerResouce.java

package org.aravind.restful.messenger.resources;

import java.util.List;

import org.aravind.restful.messenger.model.Message;
import org.aravind.restful.messenger.service.MessageService;

import jakarta.ws.rs.GET;
import jakarta.ws.rs.Path;
import jakarta.ws.rs.Produces;
import jakarta.ws.rs.core.MediaType;

@Path("/messages")
public class MessengerResource {

    @GET
    @Produces(MediaType.APPLICATION_XML)
    public List<Message> getMessages()
    {
        MessageService msgService = new MessageService();
        return msgService.getMessages();
    }
}

And here is how my pom.xml looks :

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <groupId>org.aravind.restful</groupId>
    <artifactId>messenger</artifactId>
    <packaging>war</packaging>
    <version>0.0.1-SNAPSHOT</version>
    <name>messenger</name>

    <build>
        <finalName>messenger</finalName>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>2.5.1</version>
                <inherited>true</inherited>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.glassfish.jersey</groupId>
                <artifactId>jersey-bom</artifactId>
                <version>${jersey.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <dependencies>
        <dependency>
            <groupId>org.glassfish.jersey.containers</groupId>
            <artifactId>jersey-container-servlet-core</artifactId>
            <!-- use the following artifactId if you don't need servlet 2.x compatibility -->
            <!-- artifactId>jersey-container-servlet</artifactId -->
        </dependency>
        <dependency>
            <groupId>org.glassfish.jersey.inject</groupId>
            <artifactId>jersey-hk2</artifactId>
        </dependency>
        <!-- uncomment this to get JSON support
        <dependency>
            <groupId>org.glassfish.jersey.media</groupId>
            <artifactId>jersey-media-json-binding</artifactId>
        </dependency>
        -->
    </dependencies>
    <properties>
        <jersey.version>3.0.0-M1</jersey.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>
</project>

Please help me figure this out. Thanks.

Answer 1

The link Sam suggested answers your question. You have to wrap your response as a GenericEntity. Here is the documentation from the Response class:

"It is the callers responsibility to wrap the actual entity with GenericEntity if preservation of its generic type is required."

So your code should look something like this:

 @GET
    @Produces(MediaType.APPLICATION_XML)
    public Response getMessages()
    {
        MessageService msgService = new MessageService();
        return Response.status(Status.OK)
        .entity(new GenericEntity<>(msgService.getMessages(), List.class))
        .build(); ;
    }