com.seleritycorp.context.RequestUtils.java Source code

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Here is the source code for com.seleritycorp.context.RequestUtils.java

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/*
 * Copyright (C) 2017 Selerity, Inc. (support@seleritycorp.com)
 *
 * 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 com.seleritycorp.context;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonObject;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.NameValuePair;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicNameValuePair;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;

/**
 * Low-level Utilities to make actual requests to the Context API endpoint.
 */
public class RequestUtils {
    private static final Log log = LogFactory.getLog(RequestUtils.class);

    private static final Gson GSON = new GsonBuilder().serializeNulls().create();

    protected CloseableHttpClient getHttpClient() {
        return HttpClients.createSystem();
    }

    /**
     * Context API endpoint to connect to.
     * 
     * <p/>Has to contain both protocol and path. To connect to the test endpoint, use
     * {@code https://context-api-test.seleritycorp.com/}
     */
    private final String apiServerRootUrl;

    /**
     * User agent to use for requests.
     */
    private final String userAgent;

    /**
     * Constructs RequestUtils for a given Context API endpoint.
     * 
     * @param apiServerRootUrl The Context API endpoint to use for requests. Has to contain both
     *     protocol and path. To connect to the test endpoint, use
     *     {@code https://context-api-test.seleritycorp.com/}.
     */
    public RequestUtils(String apiServerRootUrl) {
        this.apiServerRootUrl = apiServerRootUrl;
        this.userAgent = getUserAgent();
    }

    /**
     * Builds a User-Agent header value that identifies this build.
     *
     * @return the User-Agent header value that identifies this build
     */
    private String getUserAgent() {
        String buildPropertiesPath = "/META-INF/main-application/build.properties";
        Properties properties = new Properties();
        try (InputStream stream = RequestUtils.class.getResourceAsStream(buildPropertiesPath)) {
            properties.load(stream);
        } catch (IOException e) {
            System.err.println("Could not load build properties at '" + buildPropertiesPath + "'." + e.toString());
        }

        return properties.getProperty("artifactId") + "/" + properties.getProperty("version") + " (build "
                + properties.getProperty("git.description") + "/" + properties.getProperty("build.time") + ")";
    }

    /**
     * Performs a POST request
     * 
     * @param path The path for the post request (relative to the Context API endpoint)
     * @param payload Request's payload to send with the request
     * @return Context API's response json 
     * @throws Exception if server did not indicate success, or the response did not parse as JSON.
     */
    public JsonObject post(String path, JsonObject payload) throws Exception {
        String requestUrl = apiServerRootUrl + path;
        String payloadString = GSON.toJson(payload);

        List<NameValuePair> urlParameters = new ArrayList<NameValuePair>(1);
        urlParameters.add(new BasicNameValuePair("json", payloadString));

        HttpPost httpPost = new HttpPost(requestUrl);
        httpPost.setHeader("Accept", "application/json");
        httpPost.setHeader("User-Agent", userAgent);
        httpPost.setEntity(new UrlEncodedFormEntity(urlParameters));

        ResponseHandler<JsonObject> handler = new RequestResponseHandler();

        JsonObject ret;
        try (CloseableHttpClient httpclient = getHttpClient()) {
            log.debug("POSTing request to " + requestUrl + " with payload json=" + payloadString);

            long before = System.currentTimeMillis();
            ret = httpclient.execute(httpPost, handler);
            long after = System.currentTimeMillis();

            log.debug("Request took: " + (after - before) + "ms");
            log.trace("Rarsed response: " + GSON.toJson(ret));
        }
        return ret;
    }
}