update assignment of download

leijing1992 · Mar 20, 2017 · f1b7e90 · f1b7e90
1 parent 0298c1d
commit f1b7e90
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Showing 4 changed files with 106 additions and 55 deletions.
diff --git a/group02/527705641/src/com/github/fei9009/coderising0305/download/DownloadThread.java b/group02/527705641/src/com/github/fei9009/coderising0305/download/DownloadThread.java
@@ -1,6 +1,7 @@
 package com.github.fei9009.coderising0305.download;
 
 import java.io.RandomAccessFile;
+import java.util.concurrent.CyclicBarrier;
 
 import com.github.fei9009.coderising0305.download.api.Connection;
 
@@ -9,30 +10,28 @@ public class DownloadThread extends Thread{
 	Connection conn;
 	int startPos;
 	int endPos;
-
-	public DownloadThread( 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(){	
-		RandomAccessFile out = null;
 		try{
 			byte[] buffer = conn.read(startPos, endPos);
-			out = new RandomAccessFile("src/com/github/fei9009/coderising0305/download/fruits.jpg","rwd");
-			out.seek(startPos);
-			out.write(buffer);
-			FileDownloader fileloader = new FileDownloader("");
-			fileloader.getListener();
+			RandomAccessFile file = new RandomAccessFile(localFile,"rw");
+			file.seek(startPos);	
+			file.write(buffer);
+			file.close();
+			conn.close();
+			barrier.await(); 
 		}catch(Exception e){
 			e.printStackTrace();
-		}finally{
-			try{
-				out.close();
-			}catch(Exception e){
-				e.printStackTrace();
-			}
 		}
 	}
 }
diff --git a/group02/527705641/src/com/github/fei9009/coderising0305/download/FileDownloader.java b/group02/527705641/src/com/github/fei9009/coderising0305/download/FileDownloader.java
@@ -1,22 +1,27 @@
 package com.github.fei9009.coderising0305.download;
 
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import java.util.concurrent.CyclicBarrier;
+
 import com.github.fei9009.coderising0305.download.api.Connection;
 import com.github.fei9009.coderising0305.download.api.ConnectionException;
 import com.github.fei9009.coderising0305.download.api.ConnectionManager;
 import com.github.fei9009.coderising0305.download.api.DownloadListener;
 
 public class FileDownloader {
 
-	String url;
-
+	private String url;
+	private String localFile;
 	DownloadListener listener;
-
 	ConnectionManager cm;
 
+	//At most 3 threads
+	private static final int DOWNLOAD_TRHEAD_NUM = 3;
 
-	public FileDownloader(String _url) {
+	public FileDownloader(String _url, String localFile) {
 		this.url = _url;
-
+		this.localFile = localFile;
 	}
 
 	public void execute(){
@@ -33,24 +38,28 @@ public void execute(){
 		// 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();	
-			int count = 6;
-			int block = length/10024/count;
-			for (int i = 1;i <= count; i++){
-				int startPos = (i-1) * block;
-				int endPos = i * block - 1;
-				if (i == count) {
-					endPos = length;
-				}
+			createPlaceHolderFile(this.localFile, length);			
+
+			int[][] ranges = allocateDownloadRange(DOWNLOAD_TRHEAD_NUM, length);
+
+			for(int i=0; i< DOWNLOAD_TRHEAD_NUM; i++){
+				DownloadThread thread = new DownloadThread(cm.open(url), ranges[i][0], ranges[i][1], localFile, barrier);
+				thread.start();				
 			}
-			new DownloadThread(conn,0,length-1).start();
 
-		} catch (ConnectionException e) {			
+		} catch (Exception e) {			
 			e.printStackTrace();
 		}finally{
 			if(conn != null){
@@ -59,6 +68,33 @@ public void execute(){
 		}
 	}
 
+	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();
+	}
+
+	private int[][] allocateDownloadRange(int threadNum, int contentLen){
+		int[][] ranges = new int[threadNum][2];
+
+		int eachThreadSize = contentLen / threadNum;
+		int left = contentLen % threadNum;
+
+		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;
+	}
+
 	public void setListener(DownloadListener listener) {
 		this.listener = listener;
 	}

diff --git a/group02/527705641/src/com/github/fei9009/coderising0305/download/FileDownloaderTest.java b/group02/527705641/src/com/github/fei9009/coderising0305/download/FileDownloaderTest.java
@@ -23,9 +23,9 @@ public void tearDown() throws Exception {
 	@Test
 	public void testDownload() {
 
-		String url = "http://inews.gtimg.com/newsapp_bt/0/1209438116/1000";
+		String url = "http://images2015.cnblogs.com/blog/610238/201604/610238-20160421154632101-286208268.png";
 
-		FileDownloader downloader = new FileDownloader(url);
+		FileDownloader downloader = new FileDownloader(url,"c:\\ctest.jpg");
 
 
 		ConnectionManager cm = new ConnectionManagerImpl();
@@ -54,7 +54,6 @@ public void notifyFinished() {
 		}
 		System.out.println("下载完成！");
 
-
 
 	}
 

diff --git a/group02/527705641/src/com/github/fei9009/coderising0305/download/impl/ConnectionImpl.java b/group02/527705641/src/com/github/fei9009/coderising0305/download/impl/ConnectionImpl.java
@@ -3,49 +3,66 @@
 import java.io.BufferedInputStream;
 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.github.fei9009.coderising0305.download.api.Connection;
+import com.github.fei9009.coderising0305.download.api.ConnectionException;
 
 
 public class ConnectionImpl implements Connection{
 
-	private String url;
+	URL url;
+	static final int BUFFER_SIZE = 1024;
 
-	public ConnectionImpl(String url){
-		this.url=url;
+	ConnectionImpl(String _url) throws ConnectionException{
+		try {			
+			url = new URL(_url);
+		} catch (MalformedURLException e) {			
+			throw new ConnectionException();
+		}
 	}
 
 	@Override
 	public byte[] read(int startPos, int endPos) throws IOException {
 
-		URL url = new URL(this.url);
-		HttpURLConnection conn = (HttpURLConnection)url.openConnection();
-		conn.setRequestProperty("Range", "bytes="+startPos+"-"+endPos);
-		BufferedInputStream in = new BufferedInputStream(conn.getInputStream());
-		ByteArrayOutputStream out = new ByteArrayOutputStream(1024);
-		byte[] buffer = new byte[1024];
-		int size = 0;         
-        while ((size = in.read(buffer)) != -1) {         
-            out.write(buffer, 0, size);         
+		HttpURLConnection httpConn = (HttpURLConnection)url.openConnection();
+		httpConn.setRequestProperty("Range", "bytes=" + startPos + "-"+ endPos);
+		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);
         }
-        byte[] b = out.toByteArray();
-        out.close();
-        in.close();
-		return b;
+		return baos.toByteArray();
 	}
 
 	@Override
 	public int getContentLength() {
 
-		try{
-			URL u = new URL(url);
-			HttpURLConnection conn = (HttpURLConnection)u.openConnection();
-			return conn.getContentLength();
-		}catch(Exception e){
+		URLConnection con;
+		try {
+			con = url.openConnection();
+			return con.getContentLength(); 
+
+		} catch (IOException e) {			
 			e.printStackTrace();
-		}
+		}  
 		return -1;
 	}