Merge pull request #46 from starlight0405/master

thrid homework

group16/2816977791/thirdExercise/src/DownloadThread.java

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+import api.Connection;
+
+import java.io.RandomAccessFile;
+import java.util.concurrent.CyclicBarrier;
+
+public class DownloadThread extends Thread {
+
+    Connection conn;
+    int startPos;
+    int endPos;
+
+    private CyclicBarrier barrier;
+
+    public DownloadThread(Connection conn, int startPos, int endPos, CyclicBarrier barrier) {
+
+        this.conn = conn;
+        this.startPos = startPos;
+        this.endPos = endPos;
+        this.barrier = barrier;
+    }
+
+    public void run() {
+        try {
+            byte[] buffer = conn.read(startPos, endPos);
+            RandomAccessFile raf = new RandomAccessFile("/Users/nvarchar/example.jpg", "rw");
+            raf.seek(startPos);
+            raf.write(buffer);
+            raf.close();
+            barrier.await();
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
+}

group16/2816977791/thirdExercise/src/FileDownloader.java

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+import api.Connection;
+import api.ConnectionException;
+import api.ConnectionManager;
+import api.DownloadListener;
+
+import java.util.concurrent.CyclicBarrier;
+
+
+public class FileDownloader {
+
+    String url;
+
+    DownloadListener listener;
+
+    ConnectionManager cm;
+
+    private static final int THREAD_NUM = 10;
+
+
+    public FileDownloader(String _url) {
+        this.url = _url;
+
+    }
+
+    public void execute() {
+        // (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。
+        CyclicBarrier barrier = new CyclicBarrier(THREAD_NUM, new Runnable() {
+            @Override
+            public void run() {
+                listener.notifyFinished();
+            }
+        });
+        Connection conn = null;
+        try {
+            //(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）
+            conn = cm.open(this.url);
+
+            // 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
+            int length = conn.getContentLength();
+
+            // 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
+            int start = 0;
+            int endPos = 0;
+            for (int i = 0; i < THREAD_NUM; i++) {
+                endPos = start + length / THREAD_NUM;
+                System.out.println(start + "=====" + endPos);
+                new DownloadThread(conn, start, endPos > (length - 1) ? length - 1 : endPos, barrier).start();
+                start = endPos + 1;
+            }
+        } catch (ConnectionException e) {
+            e.printStackTrace();
+        } finally {
+            if (conn != null) {
+                conn.close();
+            }
+        }
+    }
+
+    public void setListener(DownloadListener listener) {
+        this.listener = listener;
+    }
+
+
+    public void setConnectionManager(ConnectionManager ucm) {
+        this.cm = ucm;
+    }
+
+    public DownloadListener getListener() {
+        return this.listener;
+    }
+
+}

group16/2816977791/thirdExercise/src/FileDownloaderTest.java

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+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import api.ConnectionManager;
+import api.DownloadListener;
+import 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://cdn.pixabay.com/photo/2017/03/31/15/34/sunset-2191645_1280.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！");
+
+
+    }
+
+}

group16/2816977791/thirdExercise/src/api/Connection.java

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+package 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();
+}

group16/2816977791/thirdExercise/src/api/ConnectionException.java

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+package api;
+
+public class ConnectionException extends Exception {
+
+}

group16/2816977791/thirdExercise/src/api/ConnectionManager.java

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+package 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;	
+}

group16/2816977791/thirdExercise/src/api/DownloadListener.java

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+package api;
+
+public interface DownloadListener {
+	public void notifyFinished();
+}

group16/2816977791/thirdExercise/src/basic/Iterator.java

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+package basic;
+
+/**
+ * @author nvarchar
+ *         date 2017/3/27
+ */
+public interface Iterator {
+    boolean hasNext();
+
+    Object next();
+}