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Merge pull request onlyliuxin#8 from honokaBiu/master
implement FileDownloader by Korben
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‎group20/1107837739/1107837739Learning/src/org/korben/coderising/download/DownloadThread.java

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package org.korben.coderising.download;
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import java.io.IOException;
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import java.io.RandomAccessFile;
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import org.korben.coderising.download.api.Connection;
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import org.korben.coderising.download.api.ConnectionException;
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import org.korben.coderising.download.api.ConnectionManager;
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import org.korben.coderising.download.api.DownloadListener;
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public class DownloadThread extends Thread {
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private int endPos;
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private int startPos;
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private String url;
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private String destFilePath;
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private ConnectionManager connManager;
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private DownloadListener downloadListener;
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public DownloadThread(ConnectionManager connManager, String url, int startPos, int endPos, String destFilePath,
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DownloadListener downloadListener) {
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this.url = url;
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this.endPos = endPos;
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this.startPos = startPos;
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this.connManager = connManager;
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this.destFilePath = destFilePath;
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this.downloadListener = downloadListener;
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}
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@Override
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public void run() {
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Connection conn = null;
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RandomAccessFile randomAccessFile = null;
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try {
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doLog("BIN");
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conn = connManager.open(url, startPos, endPos);
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byte[] read = conn.read(startPos, endPos);
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String _filePath = destFilePath;
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if (_filePath == null || _filePath.length() == 0) {
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_filePath = conn.getFileName();
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}
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randomAccessFile = new RandomAccessFile(_filePath, "rw");
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randomAccessFile.seek(startPos);
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randomAccessFile.write(read);
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doLog("END");
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} catch (IOException e) {
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doLog("EXP");
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e.printStackTrace();
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} catch (ConnectionException e) {
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doLog("EXP");
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e.printStackTrace();
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} finally {
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if (randomAccessFile != null) {
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try {
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randomAccessFile.close();
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} catch (IOException e) {
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e.printStackTrace();
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}
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}
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if (conn != null) {
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conn.close();
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}
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if (downloadListener != null) {
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downloadListener.notifyFinished();
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}
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}
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}
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private void doLog(String action) {
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System.out.println(
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"*********** " + action
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+ " ["
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+ startPos
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+ "-"
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+ endPos
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+ "]"
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+ " ***********");
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}
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}

‎group20/1107837739/1107837739Learning/src/org/korben/coderising/download/FileDownloader.java

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package org.korben.coderising.download;
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import java.util.concurrent.atomic.AtomicInteger;
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import org.korben.coderising.download.api.ConnectionException;
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import org.korben.coderising.download.api.ConnectionManager;
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import org.korben.coderising.download.api.DownloadListener;
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public class FileDownloader {
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private String url;
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private DownloadListener listener;
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private ConnectionManager cm;
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private AtomicInteger atomicInteger;
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public FileDownloader(String _url) {
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this.url = _url;
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atomicInteger = new AtomicInteger();
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}
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/**
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* 在这里实现你的代码， 注意： 需要用多线程实现下载
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* 这个类依赖于其他几个接口, 你需要写这几个接口的实现代码
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* (1) ConnectionManager , 可以打开一个连接，通过Connection可以读取其中的一段（用startPos, endPos来指定）
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* (2) DownloadListener, 由于是多线程下载， 调用这个类的客户端不知道什么时候结束，所以你需要实现当所有
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* 线程都执行完以后， 调用listener的notifiedFinished方法， 这样客户端就能收到通知。
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* 具体的实现思路：
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* 1. 需要调用ConnectionManager的open方法打开连接， 然后通过Connection.getContentLength方法获得文件的长度
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* 2. 至少启动3个线程下载， 注意每个线程需要先调用ConnectionManager的open方法
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* 然后调用read方法， read方法中有读取文件的开始位置和结束位置的参数， 返回值是byte[]数组
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* 3. 把byte数组写入到文件中
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* 4. 所有的线程都下载完成以后， 需要调用listener的notifiedFinished方法
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*
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* 下面的代码是示例代码， 也就是说只有一个线程， 你需要改造成多线程的。
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*/
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public void execute() {
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try {
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int threadCount = 5;
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int length = this.cm.getContentLength(this.url);
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for (int i = 0; i < threadCount; i++) {
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int threadLoadLength = length / threadCount;
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int startPos = threadLoadLength * i;
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int endPos;
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if (i != threadCount - 1) {
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endPos = threadLoadLength * (i + 1) - 1;
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} else {
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endPos = length - 1;
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}
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atomicInteger.getAndIncrement();
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new DownloadThread(cm, this.url, startPos, endPos, null, new DownloadListener() {
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@Override
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public void notifyFinished() {
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if (atomicInteger.decrementAndGet() == 0) {
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if (FileDownloader.this.listener != null) {
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FileDownloader.this.listener.notifyFinished();
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}
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}
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}
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}).start();
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}
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} catch (ConnectionException e) {
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e.printStackTrace();
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}
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}
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public void setConnectionManager(ConnectionManager ucm) {
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this.cm = ucm;
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}
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public DownloadListener getListener() {
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return this.listener;
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}
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public void setListener(DownloadListener listener) {
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this.listener = listener;
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}
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}

‎group20/1107837739/1107837739Learning/src/org/korben/coderising/download/FileDownloaderTest.java

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package org.korben.coderising.download;
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import org.junit.After;
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import org.junit.Before;
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import org.junit.Test;
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import org.korben.coderising.download.api.ConnectionManager;
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import org.korben.coderising.download.api.DownloadListener;
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import org.korben.coderising.download.impl.ConnectionManagerImpl;
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public class FileDownloaderTest {
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boolean downloadFinished = false;
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@Before
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public void setUp() throws Exception {
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}
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@After
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public void tearDown() throws Exception {
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}
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@Test
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public void testDownload() {
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String url = "https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1489721424&di=1fda6467501ab1d5e5bff43e801d14ee&imgtype=jpg&er=1&src=http%3A%2F%2Fimg4.duitang.com%2Fuploads%2Fitem%2F201507%2F30%2F20150730163204_A24MX.thumb.700_0.jpeg";
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//String url = "http://apache.fayea.com/maven/maven-3/3.3.9/binaries/apache-maven-3.3.9-bin.tar.gz";
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FileDownloader downloader = new FileDownloader(url);
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ConnectionManager cm = new ConnectionManagerImpl();
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downloader.setConnectionManager(cm);
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downloader.setListener(new DownloadListener() {
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@Override
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public void notifyFinished() {
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downloadFinished = true;
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}
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});
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downloader.execute();
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// 等待多线程下载程序执行完毕
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while (!downloadFinished) {
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try {
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System.out.println("还没有下载完成，休眠五秒");
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//休眠5秒
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Thread.sleep(5000);
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} catch (InterruptedException e) {
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e.printStackTrace();
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}
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}
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System.out.println("下载完成！");
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}
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}

‎group20/1107837739/1107837739Learning/src/org/korben/coderising/download/api/Connection.java

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package org.korben.coderising.download.api;
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import java.io.IOException;
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public interface Connection {
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/**
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* 给定开始和结束位置， 读取数据， 返回值是字节数组
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*
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* @param startPos 开始位置， 从0开始
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* @param endPos 结束位置
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* @return 读取的字节数组
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*/
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byte[] read(int startPos, int endPos) throws IOException;
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/**
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* 得到数据内容的长度
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*
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* @return 数据内容长度
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*/
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int getContentLength();
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/**
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* 关闭连接
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*/
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void close();
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/**
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* 获取下载文件的文件名
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*
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* @return 文件名
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*/
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String getFileName();
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}

‎group20/1107837739/1107837739Learning/src/org/korben/coderising/download/api/ConnectionException.java

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package org.korben.coderising.download.api;
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public class ConnectionException extends Exception {
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public ConnectionException(Exception e) {
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super(e);
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}
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public ConnectionException(String msg) {
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super(msg);
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}
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}

‎group20/1107837739/1107837739Learning/src/org/korben/coderising/download/api/ConnectionManager.java

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package org.korben.coderising.download.api;
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public interface ConnectionManager {
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/**
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* 给定一个url , 打开一个连接
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*
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* @param url 连接地址
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* @param startPos 读取文件的起始位置
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* @param endPos 读取文件的结束位置
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* @return 连接
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*/
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Connection open(String url, int startPos, int endPos) throws ConnectionException;
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/**
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* 获取文件长度
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*
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* @param url 连接地址
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* @return 文件长度
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*/
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int getContentLength(String url) throws ConnectionException;
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}

‎group20/1107837739/1107837739Learning/src/org/korben/coderising/download/api/DownloadListener.java

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package org.korben.coderising.download.api;
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public interface DownloadListener {
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void notifyFinished();
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}

‎group20/1107837739/1107837739Learning/src/org/korben/coderising/download/impl/ConnectionImpl.java

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package org.korben.coderising.download.impl;
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import java.io.ByteArrayOutputStream;
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import java.io.IOException;
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import java.io.InputStream;
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import java.net.HttpURLConnection;
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import org.korben.coderising.download.api.Connection;
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public class ConnectionImpl implements Connection {
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private static final int BUFFER_SIZE = 4096;
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private HttpURLConnection httpConn;
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private String fileUrl;
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private InputStream inputStream;
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public ConnectionImpl(HttpURLConnection httpConn, String fileUrl) {
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this.httpConn = httpConn;
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this.fileUrl = fileUrl;
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}
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@Override
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public byte[] read(int startPos, int endPos) throws IOException {
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if (endPos < startPos) {
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throw new IllegalArgumentException("argument endPos[" + endPos + "] less than startPos[" + startPos + "]");
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}
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int bytesNeed2Read = endPos - startPos + 1;
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if (bytesNeed2Read > getContentLength()) {
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throw new IllegalArgumentException(
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"endPos[" + endPos + "] is bigger than content length[" + getContentLength() + "]");
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}
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inputStream = httpConn.getInputStream();
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ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
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byte[] buffer = new byte[Math.min(bytesNeed2Read, BUFFER_SIZE)];
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int read;
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long startTime = System.currentTimeMillis();
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final long progressInterval = 2000;
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while ((read = inputStream.read(buffer)) != -1) {
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byteArrayOutputStream.write(buffer, 0, read);
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if (System.currentTimeMillis() - startTime > progressInterval) {
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startTime = System.currentTimeMillis();
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System.out.println(String.format(Thread.currentThread().getName() +
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" [%.2f%%]", byteArrayOutputStream.size() * 100.0 / bytesNeed2Read)
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);
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}
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}
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System.out.println(String.format(Thread.currentThread().getName() + " [%.2f%%]", 100.0));
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System.out.println("bytes read: " + byteArrayOutputStream.size());
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return byteArrayOutputStream.toByteArray();
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}
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@Override
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public int getContentLength() {
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if (httpConn != null) {
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return httpConn.getContentLength();
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}
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return 0;
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}
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@Override
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public void close() {
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if (inputStream != null) {
67+
try {
68+
inputStream.close();
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} catch (IOException e) {
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e.printStackTrace();
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}
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}
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if (httpConn != null) {
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httpConn.disconnect();
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}
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}
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@Override
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public String getFileName() {
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String disposition = httpConn.getHeaderField("Content-Disposition");
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if (disposition != null) {
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// extracts file name from header field
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int index = disposition.indexOf("filename=");
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if (index > 0) {
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return disposition.substring(index + 10,
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disposition.length() - 1);
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}
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}
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// extracts file name from URL
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return fileUrl.substring(fileUrl.lastIndexOf("/") + 1,
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fileUrl.length());
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}
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}

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