HttpJarDownloader.java

/*
 * Copyright 2016 ANI Technologies Pvt. Ltd.
 *
 * 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.olacabs.fabric.compute.builder.impl;

import com.google.common.base.Strings;
import org.apache.http.Header;
import org.apache.http.HeaderElement;
import org.apache.http.HttpStatus;
import org.apache.http.NameValuePair;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.impl.conn.PoolingHttpClientConnectionManager;
import org.apache.http.util.EntityUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.net.URI;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.FileAttribute;
import java.nio.file.attribute.PosixFilePermission;
import java.nio.file.attribute.PosixFilePermissions;
import java.util.Set;

/**
 * TODO javadoc.
 */
public class HttpJarDownloader implements JarDownloader{
    private static final Logger LOGGER = LoggerFactory.getLogger(HttpJarDownloader.class);

    private final String tmpDirectory;
    private final CloseableHttpClient httpClient;


    public HttpJarDownloader() throws Exception {
        FileAttribute<Set<PosixFilePermission>> perms =
                PosixFilePermissions.asFileAttribute(PosixFilePermissions.fromString("rwxr-xr-x"));
        Path createdPath = Files.createTempDirectory(null, perms);
        this.tmpDirectory = createdPath.toAbsolutePath().toString();

        PoolingHttpClientConnectionManager cm = new PoolingHttpClientConnectionManager();
        cm.setMaxTotal(20);

        httpClient = HttpClients.custom().setConnectionManager(cm).build();
    }

    public Path download(final String url) {
        HttpGet httpGet = new HttpGet(URI.create(url));
        CloseableHttpResponse response = null;
        try {
            response = httpClient.execute(httpGet);
            if (HttpStatus.SC_OK != response.getStatusLine().getStatusCode()) {
                throw new RuntimeException(
                    String.format("Server returned [%d][%s] for url: %s",
                        response.getStatusLine().getStatusCode(),
                        response.getStatusLine().getReasonPhrase(),
                        url));
            }
            Header[] headers = response.getHeaders("Content-Disposition");
            String filename = null;
            if (null != headers) {
                for (Header header : headers) {
                    for (HeaderElement headerElement : header.getElements()) {
                        if (!headerElement.getName().equalsIgnoreCase("attachment")) {
                            continue;
                        }
                        NameValuePair attachment = headerElement.getParameterByName("filename");
                        if (attachment != null) {
                            filename = attachment.getValue();
                        }
                    }
                }
            }
            if (Strings.isNullOrEmpty(filename)) {
                String[] nameParts = url.split("/");
                filename = nameParts[nameParts.length - 1];
            }
            return Files.write(Paths.get(this.tmpDirectory, filename), EntityUtils.toByteArray(response.getEntity()));
        } catch (IOException e) {
            throw new RuntimeException("Error loading class from: " + url, e);
        } finally {
            if (null != response) {
                try {
                    response.close();
                } catch (IOException e) {
                    LOGGER.error("Could not close connection to server: ", e);
                }
            }
        }
    }
}