Merge pull request #33 from zhoubofeng/master

Master

group14/598808350/2017project/src/com/coderising/download/DownloadThread.java

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+package com.coderising.download;
+
+import java.io.RandomAccessFile;
+import java.util.concurrent.CyclicBarrier;
+
+import com.coderising.download.api.Connection;
+
+public class DownloadThread extends Thread{
+
+	Connection conn;
+	int startPos;
+	int endPos;
+	String localFile;
+	CyclicBarrier barrier;
+
+	public DownloadThread( Connection conn, int startPos, int endPos,String localFile,CyclicBarrier barrier){
+
+		this.conn = conn;		
+		this.startPos = startPos;
+		this.endPos = endPos;
+		this.localFile = localFile;
+		this.barrier = barrier;
+	}
+	public void run(){	
+		try{
+			System.out.println("begin to read ["+startPos+"-"+endPos+"]");
+			byte[] data = conn.read(startPos, endPos);
+			RandomAccessFile file = new RandomAccessFile(localFile,"rw");
+			file.seek(startPos);
+			file.write(data);
+
+			file.close();
+			conn.close();
+			barrier.await();
+
+		}catch(Exception e){
+			e.printStackTrace();
+		}
+	}
+}

group14/598808350/2017project/src/com/coderising/download/FileDownloader.java

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+package com.coderising.download;
+
+import java.io.RandomAccessFile;
+import java.util.concurrent.CyclicBarrier;
+
+import com.coderising.download.api.Connection;
+import com.coderising.download.api.ConnectionException;
+import com.coderising.download.api.ConnectionManager;
+import com.coderising.download.api.DownloadListener;
+
+
+public class FileDownloader {
+
+	private String url;
+
+	private String localFile;
+
+	DownloadListener listener;
+
+	ConnectionManager cm;
+
+	private static final int DOWNLOAD_TRHEAD_NUM = 3;
+
+	public FileDownloader(String _url,String localFile) {
+		this.url = _url;
+		this.localFile = localFile;
+	}
+
+	public void execute(){
+		// 在这里实现你的代码， 注意： 需要用多线程实现下载
+		// 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
+		// (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）
+		// (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
+		//     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。
+		// 具体的实现思路：
+		// 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
+		// 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
+		// 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
+		// 3. 把byte数组写入到文件中
+		// 4. 所有的线程都下载完成以后， 需要调用listener的notifiedFinished方法
+
+		// 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。
+
+		CyclicBarrier barrier = new CyclicBarrier(DOWNLOAD_TRHEAD_NUM,new Runnable(){
+			public void run(){
+				listener.notifyFinished();
+			}
+		});
+
+
+		Connection conn = null;
+		try {
+
+			conn = cm.open(this.url);
+
+			int length = conn.getContentLength();	
+
+			createPlaceHolderFile(this.localFile,length);
+
+			int[][] rangs = allocateDownloadRange(DOWNLOAD_TRHEAD_NUM,length);
+			for(int i=0;i<DOWNLOAD_TRHEAD_NUM;i++){
+
+				DownloadThread thread = new DownloadThread(cm.open(url),rangs[i][0],rangs[i][1],localFile,barrier);
+				thread.start();
+			}
+
+
+
+		} catch (Exception e) {			
+			e.printStackTrace();
+		}finally{
+			if(conn != null){
+				conn.close();
+			}
+		}
+
+
+
+
+	}
+
+	private int[][] allocateDownloadRange(int downloadThreadNum, int length) {
+		int[][] rangs = new int [downloadThreadNum][2];
+		int eachThreadSize = length;
+		int left = length % downloadThreadNum;
+		for(int i=0;i<downloadThreadNum;i++){
+			int startPos = i*eachThreadSize;
+			int endPos = (i+1)*eachThreadSize -1;
+			if(i == downloadThreadNum-1){
+				endPos += left;
+			}
+
+			rangs[i][0] = startPos;
+			rangs[i][1] = endPos;
+		}
+		return rangs;
+	}
+
+	/**
+	 * 创建文件，占位
+	 * @param localFile2
+	 * @param length
+	 */
+	private void createPlaceHolderFile(String localFile2, int length)throws Exception {
+
+		RandomAccessFile file = new RandomAccessFile(localFile2	, "rw");
+		for(int i=0;i<length;i++){
+			file.write(0);
+		}
+		file.close();
+	}
+
+	public void setListener(DownloadListener listener) {
+		this.listener = listener;
+	}
+
+
+
+	public void setConnectionManager(ConnectionManager ucm){
+		this.cm = ucm;
+	}
+
+	public DownloadListener getListener(){
+		return this.listener;
+	}
+
+}

group14/598808350/2017project/src/com/coderising/download/FileDownloaderTest.java

@@ -0,0 +1,60 @@
+package com.coderising.download;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import com.coderising.download.api.ConnectionManager;
+import com.coderising.download.api.DownloadListener;
+import com.coderising.download.impl.ConnectionManagerImpl;
+
+public class FileDownloaderTest {
+	boolean downloadFinished = false;
+	@Before
+	public void setUp() throws Exception {
+	}
+
+	@After
+	public void tearDown() throws Exception {
+	}
+
+	@Test
+	public void testDownload() {
+
+		String url = "https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1489836924867&di=68eb122b4c92d6b5e2f3af6d7331290e&imgtype=0&src=http%3A%2F%2Fcdn.duitang.com%2Fuploads%2Fitem%2F201210%2F21%2F20121021202014_kAAr3.thumb.600_0.jpeg";
+		String localFile = "c:\\aa.jpg";
+
+		FileDownloader downloader = new FileDownloader(url,localFile);
+
+
+		ConnectionManager cm = new ConnectionManagerImpl();
+		downloader.setConnectionManager(cm);
+
+		downloader.setListener(new DownloadListener() {
+			@Override
+			public void notifyFinished() {
+				downloadFinished = true;
+			}
+
+		});
+
+
+		downloader.execute();
+
+		// 等待多线程下载程序执行完毕
+		while (!downloadFinished) {
+			try {
+				System.out.println("还没有下载完成，休眠五秒");
+				//休眠5秒
+				Thread.sleep(5000);
+			} catch (InterruptedException e) {				
+				e.printStackTrace();
+			}
+		}
+		System.out.println("下载完成！");
+
+
+
+	}
+
+}

group14/598808350/2017project/src/com/coderising/download/api/Connection.java

@@ -0,0 +1,23 @@
+package com.coderising.download.api;
+
+import java.io.IOException;
+
+public interface Connection {
+	/**
+	 * 给定开始和结束位置， 读取数据， 返回值是字节数组
+	 * @param startPos 开始位置， 从0开始
+	 * @param endPos 结束位置
+	 * @return
+	 */
+	public byte[] read(int startPos,int endPos) throws IOException;
+	/**
+	 * 得到数据内容的长度
+	 * @return
+	 */
+	public int getContentLength();
+
+	/**
+	 * 关闭连接
+	 */
+	public void close();
+}

group14/598808350/2017project/src/com/coderising/download/api/ConnectionException.java

@@ -0,0 +1,8 @@
+package com.coderising.download.api;
+
+public class ConnectionException extends Exception {
+
+	public ConnectionException(Exception e){
+		super(e);
+	}
+}

group14/598808350/2017project/src/com/coderising/download/api/ConnectionManager.java

@@ -0,0 +1,10 @@
+package com.coderising.download.api;
+
+public interface ConnectionManager {
+	/**
+	 * 给定一个url , 打开一个连接
+	 * @param url
+	 * @return
+	 */
+	public Connection open(String url) throws ConnectionException;	
+}

group14/598808350/2017project/src/com/coderising/download/api/DownloadListener.java

@@ -0,0 +1,5 @@
+package com.coderising.download.api;
+
+public interface DownloadListener {
+	public void notifyFinished();
+}

group14/598808350/2017project/src/com/coderising/download/impl/ConnectionImpl.java

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+package com.coderising.download.impl;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.HttpURLConnection;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.net.URLConnection;
+import java.util.Arrays;
+
+import com.coderising.download.api.Connection;
+
+public class ConnectionImpl implements Connection{
+
+	URL url;
+	static final int BUFFER_SIZE = 1024;
+
+	ConnectionImpl (String _url){
+		try {
+			url = new URL(_url);
+		} catch (MalformedURLException e) {
+			// TODO Auto-generated catch block
+			e.printStackTrace();
+		}
+	}
+
+	@Override
+	public byte[] read(int startPos, int endPos) throws IOException {
+		HttpURLConnection httpConn = (HttpURLConnection)url.openConnection();
+
+		InputStream is = httpConn.getInputStream();
+
+		byte[] buff= new byte[BUFFER_SIZE];
+		int totalLen = endPos - startPos +1;
+		ByteArrayOutputStream  baos = new ByteArrayOutputStream();
+		while(baos.size() < totalLen){
+			int len = is.read(buff);
+			if(len < 0){
+				break;
+			}
+			baos.write(buff,0,len);
+		}
+		if(baos.size() > totalLen){
+			byte[] data = baos.toByteArray();
+			return Arrays.copyOf(data, totalLen);
+		}
+		return baos.toByteArray();
+	}
+
+	@Override
+	public int getContentLength() {
+		URLConnection conn = null;
+		try {
+			conn = url.openConnection();
+			return conn.getContentLength();
+		} catch (IOException e) {
+			// TODO Auto-generated catch block
+			e.printStackTrace();
+		}
+		return -1;
+	}
+
+	@Override
+	public void close() {
+
+
+	}
+
+}

group14/598808350/2017project/src/com/coderising/download/impl/ConnectionManagerImpl.java

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+package com.coderising.download.impl;
+
+import com.coderising.download.api.Connection;
+import com.coderising.download.api.ConnectionException;
+import com.coderising.download.api.ConnectionManager;
+
+public class ConnectionManagerImpl implements ConnectionManager {
+
+
+	@Override
+	public Connection open(String urlStr) throws ConnectionException {
+		return new ConnectionImpl(urlStr);
+	}
+
+}