package org.apache.turbine.modules.screens;

 /*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements.  See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership.  The ASF licenses this file

  * to you under the Apache License, Version 2.0 (the

  * "License"); you may not use this file except in compliance

  * with the License.  You may obtain a copy of the License at

  *

  *   http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing,

  * software distributed under the License is distributed on an

  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

  * KIND, either express or implied.  See the License for the

  * specific language governing permissions and limitations

  * under the License.

  */

 import java.io.OutputStreamWriter;

 import java.io.PrintWriter;

 import org.apache.turbine.pipeline.PipelineData;

 import org.apache.turbine.util.RunData;

 import org.slf4j.Logger;

 import org.slf4j.LoggerFactory;

 /**

  * A Screen class for dealing with JSON requests.  Typically you would

  * extend this class and override the doOutput() method to use it by setting the JSON output into

  * rundata.setMessage( serialized ).

  * As convenience you may use inject in your extended class the Turbine service JsonService

  * Use {@link PlainJSONSecureAnnotatedScreen} if you need the user to be

  * logged in or having a special role in prior to executing the functions you provide.

  *

  * <p>Here is an example from a subclass:

  *

  * <code>

  * 

  *

  * public void doOutput(PipelineData pipelineData) throws Exception

  * {

  *     RunData data = pipelineData.getRunData();

  *     JSONStrategy strategy = null;

  *     

  *     try

  *     {

  *        strategy = new XYStrategy();

  *        // the result goes into rundata.message

  *        strategy.execute(data, jsonService);

  *     }

  *       catch ( Exception e )

  *       {

  *          log.error( "init failed for "+strategy , e);

  *          String msg = new JSONObject().put("error", e.getMessage()).toString();

  *          data.setMessage( msg );

  *       }

  *     

  *     super.doOutput(data);

  * }

  * </code>

  *

  *

  * @author gk

  * @version $Id$

  */

 public class PlainJSONScreen extends RawScreen

 {

     protected static final String JSON_TYPE = "application/json;charset=utf-8";

     protected final static int BUFFER_SIZE = 4096;

     static final Logger log = LoggerFactory.getLogger(PlainJSONScreen.class);

     /** Injected service instance */

     //@TurbineService

     //protected JsonService jsonService;

     /**

      * @see org.apache.turbine.modules.screens.RawScreen#getContentType(org.apache.turbine.pipeline.PipelineData)

      */

     @Override

     protected String getContentType(PipelineData pipelineData)

     {

         return JSON_TYPE;

     }

     /**

      * Output JSON content set into {@link RunData#getMessage()}.

      *

      * Encoding is UTF-8. @{@link #JSON_TYPE}: {@value #JSON_TYPE}.

      *

      * @param pipelineData The PipelineData object.

      */

     @Override

     protected void doOutput(PipelineData pipelineData) throws Exception

     {

         RunData data = pipelineData.getRunData();

         // read in json!

         String charset =  "UTF-8"; //request.getCharacterEncoding();

         String json_res =data.getMessage();

         log.debug( "json_res output: {}", json_res );

         PrintWriter out = new PrintWriter(

                 new OutputStreamWriter(data.getResponse().getOutputStream(),charset));

         out.print(json_res.toString());

         out.flush();

         out.close();

     }

 }