Valeandor  Dumbovitch Valeandor Dumbovitch - 3 months ago 20
JSON Question

Can't show value with json format on apache tomcat server

I've been trying to make a certain API and I need it to show result of a method on server in JSON format. If I try simple

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

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

@GET
@Produces(MediaType.TEXT_PLAIN)
public String getMessages() {
return "Hello World!";
}

}


it works but when I try to use my class where I return values in JSON format it shows some errors on the server (it works in ordinary console).

I'm new to this, hope I explained it well enough.

type Exception report

message org.glassfish.jersey.server.ContainerException: java.lang.NoClassDefFoundError: org/codehaus/jackson/map/ObjectMapper

description The server encountered an internal error that prevented it from fulfilling this request.

exception

javax.servlet.ServletException: org.glassfish.jersey.server.ContainerException: java.lang.NoClassDefFoundError: org/codehaus/jackson/map/ObjectMapper
org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:489)
org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:427)
org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:388)
org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:341)
org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:228)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
root cause

org.glassfish.jersey.server.ContainerException: java.lang.NoClassDefFoundError: org/codehaus/jackson/map/ObjectMapper
org.glassfish.jersey.servlet.internal.ResponseWriter.rethrow(ResponseWriter.java:278)
org.glassfish.jersey.servlet.internal.ResponseWriter.failure(ResponseWriter.java:260)
org.glassfish.jersey.server.ServerRuntime$Responder.process(ServerRuntime.java:509)
org.glassfish.jersey.server.ServerRuntime$2.run(ServerRuntime.java:334)
org.glassfish.jersey.internal.Errors$1.call(Errors.java:271)
org.glassfish.jersey.internal.Errors$1.call(Errors.java:267)
org.glassfish.jersey.internal.Errors.process(Errors.java:315)
org.glassfish.jersey.internal.Errors.process(Errors.java:297)
org.glassfish.jersey.internal.Errors.process(Errors.java:267)
org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:317)
org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:305)
org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1154)
org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:473)
org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:427)
org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:388)
org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:341)
org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:228)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
root cause

java.lang.NoClassDefFoundError: org/codehaus/jackson/map/ObjectMapper
valendor.messenger.ReturnJson.main(ReturnJson.java:27)
sun.reflect.GeneratedMethodAccessor19.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
java.lang.reflect.Method.invoke(Unknown Source)
org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory$1.invoke(ResourceMethodInvocationHandlerFactory.java:81)
org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher$1.run(AbstractJavaResourceMethodDispatcher.java:144)
org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:161)
org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$VoidOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:143)
org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:99)
org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:389)
org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:347)
org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:102)
org.glassfish.jersey.server.ServerRuntime$2.run(ServerRuntime.java:326)
org.glassfish.jersey.internal.Errors$1.call(Errors.java:271)
org.glassfish.jersey.internal.Errors$1.call(Errors.java:267)
org.glassfish.jersey.internal.Errors.process(Errors.java:315)
org.glassfish.jersey.internal.Errors.process(Errors.java:297)
org.glassfish.jersey.internal.Errors.process(Errors.java:267)
org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:317)
org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:305)
org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:1154)
org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:473)
org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:427)
org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:388)
org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:341)
org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:228)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
note The full stack trace of the root cause is available in the Apache Tomcat/8.0.36 logs.


thats the error

Answer

Obviously, as the error message states, you are missing the org.codehaus.jackson.map.ObjectMapper class. You have to add jackson-mapper library to your classpath, i.e. to your WEB-INF/lib folder.

If you use Maven to build your project, add the following dependency to your pom.xml:

<dependency>
    <groupId>org.codehaus.jackson</groupId>
    <artifactId>jackson-mapper-lgpl</artifactId>
    <version>1.9.13</version>
</dependency>

(replace the version with the one you want to use, 1.9.13 is the newest ATM)

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