Third——

group24/1054283210/src/com/github/xiaozi123/coding2017/thirdWork/.gitignore

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+*.class
+# Mobile Tools for Java (J2ME)
+.mtj.tmp/
+
+# Package Files #
+*.jar
+*.war
+*.ear
+
+# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
+hs_err_pid*
+
+#ide config
+.metadata
+.recommenders
+.idea/
+*.iml
+rebel.*
+.rebel.*
+
+# Idea
+*.iml
+*.ipr
+*.iws
+.idea
+
+target

group24/1054283210/src/com/github/xiaozi123/coding2017/thirdWork/DownloadThread.java

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+package com.github.xiaozi123.coding2017.thirdWork;
+
+import java.io.IOException;
+
+import com.github.xiaozi123.coding2017.thirdWork.api.Connection;
+
+
+import java.io.RandomAccessFile;
+import java.util.concurrent.CyclicBarrier;
+
+
+
+public class DownloadThread extends Thread{
+
+	Connection conn;
+	int startPos;
+	int endPos;
+	CyclicBarrier barrier;
+	String localFile;
+	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);
+			System.out.println("����һ�������ȡ�ļ��Ķ���");
+			RandomAccessFile file = new RandomAccessFile(localFile,"rw");
+			file.seek(startPos);
+			System.out.println("Ҫд������");
+			file.write(data);
+			file.close();
+			conn.close();
+			System.out.println(this.currentThread().getName()+"once over");
+			barrier.await();
+		} catch (Exception e) {
+			// TODO: handle exception
+		}
+	}
+}

group24/1054283210/src/com/github/xiaozi123/coding2017/thirdWork/FileDownloader.java

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+package com.github.xiaozi123.coding2017.thirdWork;
+
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import java.util.concurrent.CyclicBarrier;
+
+import com.github.xiaozi123.coding2017.thirdWork.api.Connection;
+import com.github.xiaozi123.coding2017.thirdWork.api.ConnectionException;
+import com.github.xiaozi123.coding2017.thirdWork.api.ConnectionManager;
+import com.github.xiaozi123.coding2017.thirdWork.api.DownloadListener;
+
+public class FileDownloader {
+	private String url;
+	private String localFile;
+	DownloadListener listener;
+	ConnectionManager cm;
+
+	private static final int DOWNLOAD_THREAD_NUM = 3;
+	public FileDownloader(String _url){
+		this.url = _url;
+//		this.localFile = localFile;
+	}
+
+	public void execute(){
+		// ������ʵ����Ĵ��룬 ע�⣺ ��Ҫ�ö��߳�ʵ������
+		// ��������������������ӿڣ�����Ҫд�⼸���ӿڵ�ʵ�ִ���
+		// ��1�� ConnectionManager  ���Դ�һ�����ӣ�ͨ��Connection���Զ�ȡ���е�һ�Σ���StartPos,endPos��ָ����
+		// ��2��DownloadListener, �����Ƕ��߳����أ����������Ŀͻ��˲�֪��ʲôʱ���������������Ҫʵ�ֵ������̶߳�ִ�����Ժ󣬵���listener��notifiedFinished�����������ͻ��˾����յ�֪ͨ
+		// �����ʵ��˼·��
+		// 1. ��Ҫ����ConnectionManager�� open ���������ӣ�Ȼ��ͨ�� Connection.getContentLength��������ļ��ij���
+		// 2. ��������3���߳����أ�ע��ÿ���߳���Ҫ�ȵ���ConnectionManager��open����
+		// 	     Ȼ����� read ������ read �������ж�ȡ�ļ��Ŀ�ʼλ�úͽ���λ�õIJ���������ֵ��byte[] ����
+		// 3.�� byte ����д�뵽�ļ���
+		// 4.���е��̶߳���������Ժ���Ҫ���� listener �� notifiedFinished ����
+
+		// ����Ĵ�����ʵ�����룬Ҳ����˵ֻ��һ���̣߳�����Ҫ����ɶ��̵߳�
+		CyclicBarrier barrier = new CyclicBarrier(DOWNLOAD_THREAD_NUM,new Runnable() {// �����е�Thread������ await����ʱ����ִ�к���� barrierAction,���ú�������߳�
+			@Override
+			public void run() {
+				listener.notifyFinished();
+			}
+		});
+
+		Connection conn = null;
+		try {
+			conn = cm.open(this.url);
+			int length = conn.getContentLength();// �õ���Ҫ�����ļ��ij���
+			createPlaceHolderFile(this.localFile,length);//ռλ
+			System.out.println("ռλ���");
+			int [][] ranges = allocateDownloadRange(DOWNLOAD_THREAD_NUM,length);// ��ÿ���̷߳��俪ʼλ�úͽ���λ��
+			// ��ʼ�����ļ�
+			System.out.println("��ʼ�����ļ�");
+			for(int i = 0; i < DOWNLOAD_THREAD_NUM; i++){
+				DownloadThread thread = new DownloadThread(
+						cm.open(url),
+						ranges[i][0],
+						ranges[i][1],
+						localFile,
+						barrier);
+				thread.start();
+				System.out.println("��" + (i+1) + "���߳��Ѿ�����");
+			}
+
+		} catch (Exception e) {
+			e.printStackTrace();
+		}finally{
+			System.out.println("�����ر�����");
+			if(conn != null){
+				conn.close();
+				System.out.println("�ر����ӳɹ�");
+			}
+		}
+	}
+
+	public void setListener(DownloadListener listener){
+		this.listener = listener;
+	}
+	public void setConnectionManager(ConnectionManager ucm){
+		this.cm = ucm;
+	}
+	public DownloadListener getListener(){
+		return this.listener;
+	}
+	private void createPlaceHolderFile(String fileName,int contentLen) throws IOException{
+		RandomAccessFile file = new RandomAccessFile(fileName,"rw");
+		for(int i = 0; i < contentLen; i++){
+			file.write(0);
+		}
+		file.close();
+	}
+	/**
+	 *  �����߳������ļ����ȣ�����һ����ά���飬��������ÿ���߳����صĿ�ʼλ�úͽ���λ��
+	 * @param threadNum
+	 * @param contentLen
+	 * @return
+	 */
+	private int [][] allocateDownloadRange(int threadNum, int contentLen){
+		int [][] ranges = new int[threadNum][2];// �ö�ά�������ÿ���̵߳Ŀ�ʼλ�úͽ���λ��
+
+		int eachThreadSize = contentLen / threadNum;// ÿ���߳���Ҫ���ص��ļ���С
+		int left = contentLen % threadNum;// ʣ�µĹ����һ���߳�������
+
+		for(int i = 0; i<threadNum; i++){
+			int startPos = i * eachThreadSize;
+			int endPos = (i+1) * eachThreadSize - 1;
+			if((i == (threadNum -1))){
+				endPos += left;
+			}
+			ranges[i][0] = startPos;
+			ranges[i][1] = endPos;
+		}
+
+		return ranges;
+	}
+}
+
+

group24/1054283210/src/com/github/xiaozi123/coding2017/thirdWork/FileDownloaderTest.java

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+package com.github.xiaozi123.coding2017.thirdWork;
+
+import java.io.FileNotFoundException;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import com.github.xiaozi123.coding2017.thirdWork.api.ConnectionManager;
+import com.github.xiaozi123.coding2017.thirdWork.api.DownloadListener;
+import com.github.xiaozi123.coding2017.thirdWork.impl.ConnectionManagerImpl;
+
+public class FileDownloaderTest {
+	boolean downloadFinished = false;
+	@Before
+	public void setUp() throws Exception {
+	}
+
+	@After
+	public void tearDown() throws Exception {
+	}
+
+	@Test
+	public void testDownload() throws FileNotFoundException {
+
+		String url = "http://localhost:8080/test.jpg";
+
+
+		FileDownloader downloader = new FileDownloader(url);
+
+
+		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！");
+
+
+
+	}
+
+}

group24/1054283210/src/com/github/xiaozi123/coding2017/thirdWork/api/Connection.java

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+package com.github.xiaozi123.coding2017.thirdWork.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();
+}

group24/1054283210/src/com/github/xiaozi123/coding2017/thirdWork/api/ConnectionException.java

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+package com.github.xiaozi123.coding2017.thirdWork.api;
+
+public class ConnectionException extends Exception {
+	public ConnectionException(Exception e){
+		super(e);
+	}
+}

group24/1054283210/src/com/github/xiaozi123/coding2017/thirdWork/api/ConnectionManager.java

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+package com.github.xiaozi123.coding2017.thirdWork.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;	
+}

group24/1054283210/src/com/github/xiaozi123/coding2017/thirdWork/api/DownloadListener.java

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+package com.github.xiaozi123.coding2017.thirdWork.api;
+
+public interface DownloadListener {
+	public void notifyFinished();
+}

group24/1054283210/src/com/github/xiaozi123/coding2017/thirdWork/impl/ConnectionImpl.java

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+package com.github.xiaozi123.coding2017.thirdWork.impl;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URL;
+import java.net.URLConnection;
+
+import com.github.xiaozi123.coding2017.thirdWork.api.Connection;
+import com.github.xiaozi123.coding2017.thirdWork.api.ConnectionException;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.net.URLConnection;
+import java.util.Arrays;
+
+
+public class ConnectionImpl implements Connection{
+	URL url;
+	static final int BUFFER_SIZE = 1024;
+
+	ConnectionImpl(String _url) throws ConnectionException{
+		try {
+			url = new URL(_url);
+		} catch (Exception e) {
+			throw new ConnectionException(e);
+		}
+	}
+	@Override
+	public byte[] read(int startPos, int endPos) throws IOException {
+		//��ʼ
+		System.out.println("��ʼ");
+		HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();
+		// ���ö�ȡ��λ��
+		httpConn.setRequestProperty("Range", "bytes=" + startPos + "-" + endPos);
+		// ��URL���ӻ��������
+		InputStream is = httpConn.getInputStream();
+
+		//is.skip(startPos);
+		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 con;
+		try {
+			con = url.openConnection();
+			return con.getContentLength();
+		} catch (Exception e) {
+			e.printStackTrace();
+		}
+		return -1;
+	}
+
+	@Override
+	public void close() {
+
+	}
+
+}