Merge pull request #8 from honokaBiu/master

implement FileDownloader by Korben

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

@@ -0,0 +1,79 @@
+package org.korben.coderising.download;
+
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import org.korben.coderising.download.api.Connection;
+import org.korben.coderising.download.api.ConnectionException;
+import org.korben.coderising.download.api.ConnectionManager;
+import org.korben.coderising.download.api.DownloadListener;
+
+public class DownloadThread extends Thread {
+
+    private int endPos;
+    private int startPos;
+    private String url;
+    private String destFilePath;
+    private ConnectionManager connManager;
+    private DownloadListener downloadListener;
+
+    public DownloadThread(ConnectionManager connManager, String url, int startPos, int endPos, String destFilePath,
+            DownloadListener downloadListener) {
+
+        this.url = url;
+        this.endPos = endPos;
+        this.startPos = startPos;
+        this.connManager = connManager;
+        this.destFilePath = destFilePath;
+        this.downloadListener = downloadListener;
+    }
+
+    @Override
+    public void run() {
+        Connection conn = null;
+        RandomAccessFile randomAccessFile = null;
+        try {
+            doLog("BIN");
+            conn = connManager.open(url, startPos, endPos);
+            byte[] read = conn.read(startPos, endPos);
+            String _filePath = destFilePath;
+            if (_filePath == null || _filePath.length() == 0) {
+                _filePath = conn.getFileName();
+            }
+            randomAccessFile = new RandomAccessFile(_filePath, "rw");
+            randomAccessFile.seek(startPos);
+            randomAccessFile.write(read);
+            doLog("END");
+        } catch (IOException e) {
+            doLog("EXP");
+            e.printStackTrace();
+        } catch (ConnectionException e) {
+            doLog("EXP");
+            e.printStackTrace();
+        } finally {
+            if (randomAccessFile != null) {
+                try {
+                    randomAccessFile.close();
+                } catch (IOException e) {
+                    e.printStackTrace();
+                }
+            }
+            if (conn != null) {
+                conn.close();
+            }
+            if (downloadListener != null) {
+                downloadListener.notifyFinished();
+            }
+        }
+    }
+
+    private void doLog(String action) {
+        System.out.println(
+                "*********** " + action
+                        + " ["
+                        + startPos
+                        + "-"
+                        + endPos
+                        + "]"
+                        + " ***********");
+    }
+}

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

@@ -0,0 +1,81 @@
+package org.korben.coderising.download;
+
+import java.util.concurrent.atomic.AtomicInteger;
+import org.korben.coderising.download.api.ConnectionException;
+import org.korben.coderising.download.api.ConnectionManager;
+import org.korben.coderising.download.api.DownloadListener;
+
+public class FileDownloader {
+
+    private String url;
+
+    private DownloadListener listener;
+
+    private ConnectionManager cm;
+
+    private AtomicInteger atomicInteger;
+
+    public FileDownloader(String _url) {
+        this.url = _url;
+        atomicInteger = new AtomicInteger();
+    }
+
+    /**
+     * 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。
+     */
+    public void execute() {
+        try {
+
+            int threadCount = 5;
+            int length = this.cm.getContentLength(this.url);
+            for (int i = 0; i < threadCount; i++) {
+
+                int threadLoadLength = length / threadCount;
+                int startPos = threadLoadLength * i;
+                int endPos;
+                if (i != threadCount - 1) {
+                    endPos = threadLoadLength * (i + 1) - 1;
+                } else {
+                    endPos = length - 1;
+                }
+                atomicInteger.getAndIncrement();
+                new DownloadThread(cm, this.url, startPos, endPos, null, new DownloadListener() {
+                    @Override
+                    public void notifyFinished() {
+                        if (atomicInteger.decrementAndGet() == 0) {
+                            if (FileDownloader.this.listener != null) {
+                                FileDownloader.this.listener.notifyFinished();
+                            }
+                        }
+                    }
+                }).start();
+            }
+        } catch (ConnectionException e) {
+            e.printStackTrace();
+        }
+    }
+
+    public void setConnectionManager(ConnectionManager ucm) {
+        this.cm = ucm;
+    }
+
+    public DownloadListener getListener() {
+        return this.listener;
+    }
+
+    public void setListener(DownloadListener listener) {
+        this.listener = listener;
+    }
+}

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

@@ -0,0 +1,54 @@
+package org.korben.coderising.download;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.korben.coderising.download.api.ConnectionManager;
+import org.korben.coderising.download.api.DownloadListener;
+import org.korben.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=1489721424&di=1fda6467501ab1d5e5bff43e801d14ee&imgtype=jpg&er=1&src=http%3A%2F%2Fimg4.duitang.com%2Fuploads%2Fitem%2F201507%2F30%2F20150730163204_A24MX.thumb.700_0.jpeg";
+        //String url = "http://apache.fayea.com/maven/maven-3/3.3.9/binaries/apache-maven-3.3.9-bin.tar.gz";
+
+        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！");
+    }
+}

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

@@ -0,0 +1,33 @@
+package org.korben.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 读取的字节数组
+     */
+    byte[] read(int startPos, int endPos) throws IOException;
+
+    /**
+     * 得到数据内容的长度
+     *
+     * @return 数据内容长度
+     */
+    int getContentLength();
+
+    /**
+     * 关闭连接
+     */
+    void close();
+
+    /**
+     * 获取下载文件的文件名
+     *
+     * @return 文件名
+     */
+    String getFileName();
+}

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

@@ -0,0 +1,11 @@
+package org.korben.coderising.download.api;
+
+public class ConnectionException extends Exception {
+    public ConnectionException(Exception e) {
+        super(e);
+    }
+
+    public ConnectionException(String msg) {
+        super(msg);
+    }
+}

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

@@ -0,0 +1,21 @@
+package org.korben.coderising.download.api;
+
+public interface ConnectionManager {
+    /**
+     * 给定一个url , 打开一个连接
+     *
+     * @param url 连接地址
+     * @param startPos 读取文件的起始位置
+     * @param endPos 读取文件的结束位置
+     * @return 连接
+     */
+    Connection open(String url, int startPos, int endPos) throws ConnectionException;
+
+    /**
+     * 获取文件长度
+     *
+     * @param url 连接地址
+     * @return 文件长度
+     */
+    int getContentLength(String url) throws ConnectionException;
+}

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

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

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

@@ -0,0 +1,93 @@
+package org.korben.coderising.download.impl;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.HttpURLConnection;
+import org.korben.coderising.download.api.Connection;
+
+public class ConnectionImpl implements Connection {
+
+    private static final int BUFFER_SIZE = 4096;
+    private HttpURLConnection httpConn;
+    private String fileUrl;
+    private InputStream inputStream;
+
+    public ConnectionImpl(HttpURLConnection httpConn, String fileUrl) {
+        this.httpConn = httpConn;
+        this.fileUrl = fileUrl;
+    }
+
+    @Override
+    public byte[] read(int startPos, int endPos) throws IOException {
+        if (endPos < startPos) {
+            throw new IllegalArgumentException("argument endPos[" + endPos + "] less than startPos[" + startPos + "]");
+        }
+        int bytesNeed2Read = endPos - startPos + 1;
+        if (bytesNeed2Read > getContentLength()) {
+            throw new IllegalArgumentException(
+                    "endPos[" + endPos + "] is bigger than content length[" + getContentLength() + "]");
+        }
+
+        inputStream = httpConn.getInputStream();
+
+        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
+        byte[] buffer = new byte[Math.min(bytesNeed2Read, BUFFER_SIZE)];
+        int read;
+
+        long startTime = System.currentTimeMillis();
+        final long progressInterval = 2000;
+        while ((read = inputStream.read(buffer)) != -1) {
+            byteArrayOutputStream.write(buffer, 0, read);
+
+            if (System.currentTimeMillis() - startTime > progressInterval) {
+                startTime = System.currentTimeMillis();
+                System.out.println(String.format(Thread.currentThread().getName() +
+                        " [%.2f%%]", byteArrayOutputStream.size() * 100.0 / bytesNeed2Read)
+                );
+            }
+        }
+        System.out.println(String.format(Thread.currentThread().getName() + " [%.2f%%]", 100.0));
+        System.out.println("bytes read: " + byteArrayOutputStream.size());
+
+        return byteArrayOutputStream.toByteArray();
+    }
+
+    @Override
+    public int getContentLength() {
+        if (httpConn != null) {
+            return httpConn.getContentLength();
+        }
+        return 0;
+    }
+
+    @Override
+    public void close() {
+        if (inputStream != null) {
+            try {
+                inputStream.close();
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        }
+        if (httpConn != null) {
+            httpConn.disconnect();
+        }
+    }
+
+    @Override
+    public String getFileName() {
+        String disposition = httpConn.getHeaderField("Content-Disposition");
+        if (disposition != null) {
+            // extracts file name from header field
+            int index = disposition.indexOf("filename=");
+            if (index > 0) {
+                return disposition.substring(index + 10,
+                        disposition.length() - 1);
+            }
+        }
+        // extracts file name from URL
+        return fileUrl.substring(fileUrl.lastIndexOf("/") + 1,
+                fileUrl.length());
+    }
+}