Restlet.handle method occurs NullPointerException

[varlinor]

When I use restlet to request RESTFUL URL, it does not work! I tried messes of solutions ,but they don't work. but when I change another restful url, restlet framework works rightly!
I just want to know, what kind of case will cause this error. below is the error info:

[2016-05-31 15:24:47] [WARNING] [System.out] [java.lang.NullPointerException]
[2016-05-31 15:24:47] [WARNING] [System.out] [ at org.restlet.Restlet.handle(Restlet.java:230)]
[2016-05-31 15:24:47] [WARNING] [System.out] [ at org.restlet.Client.handle(Client.java:174)]
[2016-05-31 15:24:47] [WARNING] [System.out] [ at org.restlet.Client.handle(Client.java:168)]

My test code is like this:

Client client=new Client(Arrays.asList(new Protocol[] { Protocol.HTTP,Protocol.HTTPS })));
String mapsUri = "http://localhost:8090/iserver/services/map-china400/rest/maps/China/queryResults.rjson?returnContent=true";
Request request=new Request(Method.POST, mapsUri);
com.supermap.services.components.commontypes.QueryParameterSet queryParams = new com.supermap.services.components.commontypes.QueryParameterSet();// 查询参数
com.supermap.services.components.commontypes.QueryParameter param = new com.supermap.services.components.commontypes.QueryParameter();
param.name = "GangAo_ln@China400";
queryParams.queryParams = new com.supermap.services.components.commontypes.QueryParameter[] { param };
queryParams.expectCount = 20;
queryParams.startRecord = 0;
JSONObject queryEntity = new JSONObject();
JsonEncoder encoder = new JsonEncoder();
String queryParamsText = encoder.toRepresentation(MediaType.APPLICATION_JSON, queryParams).getText();
// put some parameters into object
queryEntity.put("queryMode", "SqlQuery");
queryEntity.put("queryParameters", new JSONObject(queryParamsText));
queryEntity.put("spatialQueryMode", "INTERSECT");
queryEntity.put("distance", 1);
JsonRepresentation requestEntity = new JsonRepresentation(queryEntity);
request.setEntity(requestEntity);
Response response = client.handle(request);
String text = response.getEntityAsText();
System.out.println("output:"+text);

the version of restlet in my project is 2.0.11

expect your support

[thboileau]

Hello,

I'm sorry for the delay of my response.

Could you try with ClientResource class (from package org.restlet.resource)instead, it will make your code lighter:

        String mapsUri = "http://localhost:8182/iserver/services/map-china400/rest/maps/China/queryResults.rjson?returnContent=true";

com.supermap.services.components.commontypes.QueryParameterSet queryParams = new com.supermap.services.components.commontypes.QueryParameterSet();// 查询参数
com.supermap.services.components.commontypes.QueryParameter param = new com.supermap.services.components.commontypes.QueryParameter();
param.name = "GangAo_ln@China400";
queryParams.queryParams = new com.supermap.services.components.commontypes.QueryParameter[] { param };
queryParams.expectCount = 20;
queryParams.startRecord = 0;
JSONObject queryEntity = new JSONObject();
JsonEncoder encoder = new JsonEncoder();
String queryParamsText = encoder.toRepresentation(MediaType.APPLICATION_JSON, queryParams).getText();
// put some parameters into object
queryEntity.put("queryMode", "SqlQuery");
queryEntity.put("queryParameters", new JSONObject(queryParamsText));
queryEntity.put("spatialQueryMode", "INTERSECT");
queryEntity.put("distance", 1);
JsonRepresentation requestEntity = new JsonRepresentation(queryEntity);

        ClientResource cr = new ClientResource(mapsUri);
        cr.post(requestEntity);

        if (cr.getResponse().isEntityAvailable()) {
            System.out.println("Output: " + cr.getResponseEntity().getText());
        } else {
            System.out.println("nothing");
        }