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RalfNickRalfNick
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Ralf
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‎group20/925290009/第三次作业/com/coderising/download/DownloadThread.java

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package com.coderising.download;
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import java.io.File;
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import java.io.FileNotFoundException;
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import java.io.IOException;
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import java.io.RandomAccessFile;
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import com.coderising.download.api.Connection;
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import com.coderising.download.api.ConnectionException;
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import com.coderising.download.api.ConnectionManager;
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import com.coderising.download.api.DownloadListener;
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public class DownloadThread extends Thread {
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ConnectionManager cm;
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int startPos;
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int endPos;
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String url;
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DownloadListener downloadListener;
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public DownloadThread(ConnectionManager cm, String url, int startPos, int endPos, DownloadListener listener) {
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this.cm = cm;
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this.startPos = startPos;
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this.endPos = endPos;
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this.url = url;
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this.downloadListener = listener;
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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 raf = null;
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// 随机写文件的时候从哪个位置开始写
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try {
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conn = cm.open(url,startPos,endPos);
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} catch (ConnectionException e3) {
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// TODO Auto-generated catch block
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e3.printStackTrace();
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}
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try {
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byte[] byeArr = conn.read(startPos, endPos);
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System.out.println("----::" + byeArr.length);
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File file = new File("D:\\111.jpg");
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synchronized (file) {
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if (!file.exists()) {
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file.createNewFile();
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}
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raf = new RandomAccessFile(file, "rw");
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}
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//raf.setLength(34134);
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raf.seek(startPos);// 定位文件
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raf.write(byeArr);
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System.out.println("-------");
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} catch (FileNotFoundException e1) {
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// TODO Auto-generated catch block
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e1.printStackTrace();
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} catch (IOException e) {
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e.printStackTrace();
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} finally {
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try {
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if (raf != null) {
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raf.close();
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}
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} catch (Exception e2) {
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// TODO: handle exception
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e2.printStackTrace();
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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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}

‎group20/925290009/第三次作业/com/coderising/download/FileDownloader.java

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package com.coderising.download;
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import com.coderising.download.api.ConnectionManager;
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import com.coderising.download.api.DownloadListener;
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public class FileDownloader {
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String url;
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DownloadListener listener;
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ConnectionManager cm;
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int threadSum = 0;
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public FileDownloader(String _url) {
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this.url = _url;
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}
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public void execute() {
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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,
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// 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，
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// 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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// 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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// Connection conn = null;
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int threadNum = 3;
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int length = cm.getContentLength(url);
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for (int i = 0; i < threadNum; i++) {
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int threadLoadLength = length / threadNum;
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int startPos = threadLoadLength * i;
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int endPos;
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if (i != threadNum - 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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threadSum++;
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new DownloadThread(cm, this.url, startPos, endPos, new DownloadListener() {
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@Override
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public void notifyFinished() {
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if ((threadSum--) == 0) {
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if (listener != null) {
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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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}
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public void setListener(DownloadListener listener) {
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this.listener = listener;
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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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}

‎group20/925290009/第三次作业/com/coderising/download/FileDownloaderTest.java

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package com.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 com.coderising.download.api.ConnectionManager;
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import com.coderising.download.api.DownloadListener;
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import com.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 = "http://img002.21cnimg.com/photos/album/20160326/m600/B920004B5414AE4C7D6F2BAB2966491E.jpeg";
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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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}

‎group20/925290009/第三次作业/com/coderising/download/api/Connection.java

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package com.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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* @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
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*/
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public 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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* @return
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*/
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public int getContentLength();
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/**
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* 关闭连接
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*/
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public void close();
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}

‎group20/925290009/第三次作业/com/coderising/download/api/ConnectionException.java

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package com.coderising.download.api;
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public class ConnectionException extends Exception {
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/**
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*
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*/
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private static final long serialVersionUID = 4776347926322882920L;
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/**
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*
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*/
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public ConnectionException(){
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super();
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}
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}

‎group20/925290009/第三次作业/com/coderising/download/api/ConnectionManager.java

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package com.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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* @param url
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* @return
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*/
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//public Connection open(String url) throws ConnectionException;
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public int getContentLength(String url);
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Connection open(String url, int startPos, int endPos)
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throws ConnectionException;
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}

‎group20/925290009/第三次作业/com/coderising/download/api/DownloadListener.java

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

‎group20/925290009/第三次作业/com/coderising/download/impl/ConnectionImpl.java

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package com.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 com.coderising.download.api.Connection;
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public class ConnectionImpl implements Connection{
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private HttpURLConnection httpConn;
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private InputStream inputStream;
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public ConnectionImpl(HttpURLConnection httpconn) {
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// TODO Auto-generated constructor stub
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this.httpConn = httpconn;
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}
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//read() 方法有问题
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@Override
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public byte[] read(int startPos, int endPos) throws IOException {
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inputStream = httpConn.getInputStream();
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System.out.println(startPos + "----" + endPos);
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ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
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int len = 0;
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byte[] by = new byte[1024];
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while((len = inputStream.read(by))!= -1){
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byteArrayOutputStream.write(by, 0, len);
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}
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System.out.println(byteArrayOutputStream.toByteArray().length);
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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) {
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try {
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inputStream.close();
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} catch (IOException e) {
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// TODO Auto-generated catch block
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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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}

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