Restlet: using the delete method

Question

I'm a newbie with Restlet and I have a problem. I created a service that works perfectly but my client application does not. It fails when I invoke the DELETE method. GET, POST and PUT works fine.

This is my code (client):

    JSONObject object = new JSONObject();

    object.put("name", param);

    Request request = new Request(Method.DELETE, new Reference("http://localhost:8181/Restlet_Service/"));

    request.setEntity(new JsonRepresentation(object.toString()));

    Client cliente = new Client(Protocol.HTTP);
    Response response = client.handle(request);
    String text = response.getEntity().getText();

Code from the service. GET, POST and PUT methods starts with the same code:

    public class MyResource extends ServerResource {

            @Delete
            public Representation deleteUser(Representation entity) {
                    try {
                            String jsonString = (new JsonRepresentation(entity)).getJsonObject().toString();
                            Map map = (Map) (new JSONParser()).parse(jsonString);

                            if(map.size() > 0) {
                                    String message = dbc.deleteUser(map.get("name").toString());

                                    return new StringRepresentation(message, MediaType.TEXT_PLAIN);
                            } else {

                                    return new StringRepresentation("Unable to delete user", MediaType.TEXT_PLAIN);
                            }
                    } catch (Exception ex) {
                            return new StringRepresentation("ERROR: " + ex.getMessage(), MediaType.TEXT_PLAIN);
                    }
            }
    ... }

I tested each method using Advanced Rest Client in Chrome and all of them works perfectly. It fails only with my client application. This is the exception:

    java.lang.NullPointerException
            at java.io.StringReader.<init>(Unknown Source)
            at org.json.JSONTokener.<init>(JSONTokener.java:66)
            at org.json.JSONObject.<init>(JSONObject.java:402)
            at org.restlet.ext.json.JsonRepresentation.getJsonObject(JsonRepresentation.java:199)
            at service.MyResource.borrarUsuario(MyResource.java:95)
            at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
            at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
            at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
            at java.lang.reflect.Method.invoke(Unknown Source)
            at org.restlet.resource.ServerResource.doHandle(ServerResource.java:503)
            at org.restlet.resource.ServerResource.delete(ServerResource.java:208)
            at org.restlet.resource.ServerResource.doHandle(ServerResource.java:594)
            at org.restlet.resource.ServerResource.doNegotiatedHandle(ServerResource.java:649)
            at org.restlet.resource.ServerResource.doConditionalHandle(ServerResource.java:348)
            at org.restlet.resource.ServerResource.handle(ServerResource.java:952)
            at org.restlet.resource.Finder.handle(Finder.java:246)
            at org.restlet.routing.Filter.doHandle(Filter.java:159)
            at org.restlet.routing.Filter.handle(Filter.java:206)
            at org.restlet.routing.Router.doHandle(Router.java:431)
            at org.restlet.routing.Router.handle(Router.java:648)
            at org.restlet.routing.Filter.doHandle(Filter.java:159)
            at org.restlet.routing.Filter.handle(Filter.java:206)
            at org.restlet.routing.Filter.doHandle(Filter.java:159)
            at org.restlet.routing.Filter.handle(Filter.java:206)
            at org.restlet.routing.Filter.doHandle(Filter.java:159)
            at org.restlet.engine.application.StatusFilter.doHandle(StatusFilter.java:155)
            at org.restlet.routing.Filter.handle(Filter.java:206)
            at org.restlet.routing.Filter.doHandle(Filter.java:159)
            at org.restlet.routing.Filter.handle(Filter.java:206)
            at org.restlet.engine.CompositeHelper.handle(CompositeHelper.java:211)
            at org.restlet.engine.application.ApplicationHelper.handle(ApplicationHelper.java:84)
            at org.restlet.Application.handle(Application.java:381)
            at org.restlet.routing.Filter.doHandle(Filter.java:159)
            at org.restlet.routing.Filter.handle(Filter.java:206)
            at org.restlet.routing.Router.doHandle(Router.java:431)
            at org.restlet.routing.Router.handle(Router.java:648)
            at org.restlet.routing.Filter.doHandle(Filter.java:159)
            at org.restlet.routing.Filter.handle(Filter.java:206)
            at org.restlet.routing.Router.doHandle(Router.java:431)
            at org.restlet.routing.Router.handle(Router.java:648)
            at org.restlet.routing.Filter.doHandle(Filter.java:159)
            at org.restlet.routing.Filter.handle(Filter.java:206)
            at org.restlet.engine.CompositeHelper.handle(CompositeHelper.java:211)
            at org.restlet.Component.handle(Component.java:392)
            at org.restlet.Server.handle(Server.java:516)
            at org.restlet.engine.ServerHelper.handle(ServerHelper.java:72)
            at org.restlet.engine.adapter.HttpServerHelper.handle(HttpServerHelper.java:152)
            at org.restlet.ext.servlet.ServerServlet.service(ServerServlet.java:1089)
            at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
            at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
            at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
            at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
            at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
            at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
            at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
            at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
            at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:947)
            at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
            at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
            at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1009)
            at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
            at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
            at java.lang.Thread.run(Unknown Source)
    may 22, 2013 3:10:58 PM org.restlet.engine.log.LogFilter afterHandle
    INFO: 2013-05-22    15:10:58    127.0.0.1   -   127.0.0.1   8181    DELETE  /Restlet_Service/   -   200 11  17  20592 http://localhost:8181 Restlet-Framework/2.1.2 -

It is caused because the request is null and I don't know why. Any help is welcome. Thanks!

Answer 1

我的猜测是您的客户端不发送任何表示形式，因此实体为NULL，这又导致JsonTokenizer中的NPE。