executioncontext20090716/framework/webapp/src/org/ofbiz/webapp/event/AbstractJSONEventHandler.java

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 * 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,
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 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
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package org.ofbiz.webapp.event;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.io.Writer;
import java.util.Map;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import net.sf.json.JSONObject;

import org.ofbiz.base.util.UtilHttp;
import org.ofbiz.webapp.control.ConfigXMLReader.Event;
import org.ofbiz.webapp.control.ConfigXMLReader.RequestMap;

public abstract class AbstractJSONEventHandler implements EventHandler {

    public static final String module = JSONSimpleEventHandler.class.getName();
    protected EventHandler service;


    public abstract void init(ServletContext context) throws EventHandlerException;

    public String invoke(Event event, RequestMap requestMap, HttpServletRequest request, HttpServletResponse response) throws EventHandlerException {
                // call into the java handler for parameters parsing and invocation
        String respCode = service.invoke(event, requestMap, request, response);
        // pull out the service response from the request attribute
        Map<String, Object> attrMap = UtilHttp.getJSONAttributeMap(request);

        // create a JSON Object for return
        JSONObject json = JSONObject.fromObject(attrMap);
        String jsonStr = json.toString();
        if (jsonStr == null) {
            throw new EventHandlerException("JSON Object was empty; fatal error!");
        }

        // set the X-JSON content type
        response.setContentType("application/x-json");
        // jsonStr.length is not reliable for unicode characters
        try {
            response.setContentLength(jsonStr.getBytes("UTF8").length);
        } catch (UnsupportedEncodingException e) {
            throw new EventHandlerException("Problems with Json encoding", e);
        }

        // return the JSON String
        Writer out;
        try {
            out = response.getWriter();
            out.write(jsonStr);
            out.flush();
        } catch (IOException e) {
            throw new EventHandlerException("Unable to get response writer", e);
        }
        return respCode;
    }

}