javax.ws.rs.WebApplicationException：com.sun.jersey.api.MessageException：Java REST Web服务中的JSON支持

Question

Okay, this question has probably been asked before, but on all sites I've looked the explanation on "how to do this" tells me I'm doing it completely right.

I know I'm not, as I get a 500 server error on my localhost tomcat and I get the following error in my server logs:

javax.ws.rs.WebApplicationException: com.sun.jersey.api.MessageException: A message body writer for Java class com.myapp.domain.Location, and Java type class com.myapp.domain.Location, and MIME media type application/json was not found

So, what I'm trying to do is to develop a RESTful web service with Jersey (in Java). Everything is going fine, except for the fact that I want to return JSON. I can't find what I'm doing different from these people:

• How to send response as JSON in Jersey Rest
• http://www.jasonwhaley.com/blog/2011/01/18/multiple-content-types-in-jax-rs/
• https://github.com/jasonray/jersey-starterkit/wiki/Serializing-a-POJO-to-xml-or-json-using-JAXB
• https://github.com/jasonray/jersey-starterkit/wiki/Serializing-a-POJO-to-json-using-built-in-jersey-support
• http://www.vogella.com/tutorials/REST/article.html

My POJO (Location) looks like this:

package com.myapp.domain;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement()
public class Location {
    private int id;
    private double longtitude;
    private double latitude;

    public Location() {
        new Location(-1, -1, -1);
    }

    public Location(double longtitude, double latitude) {
        new Location(-1, longtitude, latitude);
    }

    public Location(int id, double longtitude, double latitude) {
        this.id = id;
        this.longtitude = longtitude;
        this.latitude = latitude;
    }

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

    public void setLongtitude(double longtitude) {
        this.longtitude = longtitude;
    }

    public void setLatitude(double latitude) {
        this.latitude = latitude;
    }

    public int getID() {
        return this.id;
    }

    public double getLongtitude() {
        return this.longtitude;
    }

    public double getLatitude() {
        return this.latitude;
    }
}

My resource looks like this:

package com.myapp.MyAPP;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;

import com.myapp.domain.Location;

@Path("Locations")
public class LocationInfo {
    @GET
    @Path("/get/{id}")
    @Produces(MediaType.APPLICATION_JSON)
    public Location getLocation(@PathParam("id") int id) {
        Location loc = new Location(3, 4.007391, 51.00237);
        return loc;
    }
}

And this is my web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns="http://java.sun.com/xml/ns/javaee" 
    xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
        http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
        id="WebApp_ID" 
        version="2.5">  
    <display-name>MyAPP</display-name> 
    <servlet> 
            <servlet-name>MyAPP REST Service</servlet-name> 
            <servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class> 
            <init-param> 
                <param-name>com.sun.jersey.config.property.packages</param-name> 
                <param-value>com.myapp.MyAPP</param-value>
            </init-param>
            <init-param>
                <param-name>com.sun.jersey.api.json.POJOMappingFeature</param-name>
                <param-value>true</param-value>
            </init-param>
            <load-on-startup>1</load-on-startup> 
    </servlet> 
    <servlet-mapping> 
            <servlet-name>MyAPP REST Service</servlet-name> 
            <url-pattern>/rest/*</url-pattern> 
    </servlet-mapping>
</web-app>

I've got these libraries included: asm-3.1.jar , jersey-client-1.17.1.jar , jersey-core-1.17.1.jar , jersey-json-1.17.1.jar , jersey-server-1.17.1.jar , jersey-servlet-1.17.jar , jsr11-api-1.1.1.jar

The one who sees what I'm not seeing gets a beer. Or at least my eternal gratitude, cause I've been looking at this for way too long and I still can't see it.

Answer 1

Okay, so I turned out orid had the right answer: I simply needed to add some extra libraries!

I probably overlooked it or most tutorials probably suppose you add all the libraries you download with jersey straight away...

So this fixed the problem: adding

• jackson-core-asl-1.9.2.jar
• jackson-jaxrs-1.9.2.jar
• jackson-mapper-asl-1.9.2.jar
• jackson-xc-1.9.2.jar

Thanks again to orid, you just saved my weekend.