org.hydracache.server.httpd.handler.BaseJsonServiceAction.java Source code

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Here is the source code for org.hydracache.server.httpd.handler.BaseJsonServiceAction.java

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/*
 * Copyright 2010 the original author or authors.
 *
 * Licensed 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.
 */
package org.hydracache.server.httpd.handler;

import static org.hydracache.server.httpd.HttpConstants.PLAIN_TEXT_RESPONSE_CONTENT_TYPE;

import java.io.IOException;
import java.io.UnsupportedEncodingException;

import org.apache.commons.lang.StringUtils;
import org.apache.http.HttpException;
import org.apache.http.HttpRequest;
import org.apache.http.HttpResponse;
import org.apache.http.entity.StringEntity;
import org.apache.log4j.Logger;

/**
 * Base http service action class with support and utility methods for JSON and
 * JSONP based protocol
 * 
 * @author Nick Zhu (nzhu@jointsource.com)
 */
public abstract class BaseJsonServiceAction {

    public static final String JSONP_CALLBACK_PARAM_NAME = "handler";

    protected static Logger log = Logger.getLogger(PrintRegistryAction.class);

    public BaseJsonServiceAction() {
        super();
    }

    /*
     * (non-Javadoc)
     * 
     * @see
     * org.hydracache.server.httpd.handler.HttpServiceAction#execute(org.apache
     * .http.HttpRequest, org.apache.http.HttpResponse)
     */
    public void execute(HttpRequest request, HttpResponse response) throws HttpException, IOException {
        String jsonString = buildJsonOutput();

        String jsonHandlerParam = getJsonHandlerParam(request);

        if (isJSONPRequest(jsonHandlerParam)) {
            jsonString = padJSONResponse(jsonString, jsonHandlerParam);
        }

        generateResponse(response, jsonString);
    }

    protected abstract String buildJsonOutput() throws IOException;

    private void generateResponse(HttpResponse response, String jsonString) throws UnsupportedEncodingException {
        StringEntity body = new StringEntity(jsonString);

        body.setContentType(PLAIN_TEXT_RESPONSE_CONTENT_TYPE);

        response.setEntity(body);
    }

    protected boolean isJSONPRequest(String jsonHandlerParam) {
        return !"null".equalsIgnoreCase(jsonHandlerParam) && StringUtils.isNotBlank(jsonHandlerParam);
    }

    protected String padJSONResponse(String jsonString, String jsonHandlerParam) {
        return jsonHandlerParam + "(" + jsonString + ")";
    }

    protected String getJsonHandlerParam(HttpRequest request) {
        return (request == null || request.getParams() == null) ? ""
                : String.valueOf(request.getParams().getParameter(JSONP_CALLBACK_PARAM_NAME));
    }

}