easyExcel实现大数据导出

/* * Copyright 2012-2019 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 * * https://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.net.*; import java.io.*; import java.nio.channels.*; import java.util.Properties; public class MavenWrapperDownloader { private static final String WRAPPER_VERSION = "0.5.5"; /** * Default URL to download the maven-wrapper.jar from, if no 'downloadUrl' is provided. */ private static final String DEFAULT_DOWNLOAD_URL = "https://repo.maven.apache.org/maven2/io/takari/maven-wrapper/" + WRAPPER_VERSION + "/maven-wrapper-" + WRAPPER_VERSION + ".jar"; /** * Path to the maven-wrapper.properties file, which might contain a downloadUrl property to * use instead of the default one. */ private static final String MAVEN_WRAPPER_PROPERTIES_PATH = ".mvn/wrapper/maven-wrapper.properties"; /** * Path where the maven-wrapper.jar will be saved to. */ private static final String MAVEN_WRAPPER_JAR_PATH = ".mvn/wrapper/maven-wrapper.jar"; /** * Name of the property which should be used to override the default download url for the wrapper. */ private static final String PROPERTY_NAME_WRAPPER_URL = "wrapperUrl"; public static void main(String args[]) { System.out.println("- Downloader started"); File baseDirectory = new File(args[0]); System.out.println("- Using base directory: " + baseDirectory.getAbsolutePath()); // If the maven-wrapper.properties exists, read it and check if it contains a custom // wrapperUrl parameter. File mavenWrapperPropertyFile = new File(baseDirectory, MAVEN_WRAPPER_PROPERTIES_PATH); String url = DEFAULT_DOWNLOAD_URL; if (mavenWrapperPropertyFile.exists()) { FileInputStream mavenWrapperPropertyFileInputStream = null; try { mavenWrapperPropertyFileInputStream = new FileInputStream(mavenWrapperPropertyFile); Properties mavenWrapperProperties = new Properties(); mavenWrapperProperties.load(mavenWrapperPropertyFileInputStream); url = mavenWrapperProperties.getProperty(PROPERTY_NAME_WRAPPER_URL, url); } catch (IOException e) { System.out.println("- ERROR loading '" + MAVEN_WRAPPER_PROPERTIES_PATH + "'"); } finally { try { if (mavenWrapperPropertyFileInputStream != null) { mavenWrapperPropertyFileInputStream.close(); } } catch (IOException e) { // Ignore ... } } } System.out.println("- Downloading from: " + url); File outputFile = new File(baseDirectory.getAbsolutePath(), MAVEN_WRAPPER_JAR_PATH); if (!outputFile.getParentFile().exists()) { if (!outputFile.getParentFile().mkdirs()) { System.out.println( "- ERROR creating output directory '" + outputFile.getParentFile().getAbsolutePath() + "'"); } } System.out.println("- Downloading to: " + outputFile.getAbsolutePath()); try { downloadFileFromURL(url, outputFile); System.out.println("Done"); System.exit(0); } catch (Throwable e) { System.out.println("- Error downloading"); e.printStackTrace(); System.exit(1); } } private static void downloadFileFromURL(String urlString, File destination) throws Exception { if (System.getenv("MVNW_USERNAME") != null && System.getenv("MVNW_PASSWORD") != null) { String username = System.getenv("MVNW_USERNAME"); char[] password = System.getenv("MVNW_PASSWORD").toCharArray(); Authenticator.setDefault(new Authenticator() { @Override protected PasswordAuthentication getPasswordAuthentication() { return new PasswordAuthentication(username, password); } }); } URL website = new URL(urlString); ReadableByteChannel rbc; rbc = Channels.newChannel(website.openStream()); FileOutputStream fos = new FileOutputStream(destination); fos.getChannel().transferFrom(rbc, 0, Long.MAX_VALUE); fos.close(); rbc.close(); } }