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package javaclass.download;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.logging.Level;
import java.util.logging.Logger;
import javaclass.download.api.Connection;
import javaclass.download.api.ConnectionException;
import javaclass.download.api.ConnectionManager;
import javaclass.download.api.DownloadListener;
public class FileDownloader {
String url;
DownloadListener listener;
ConnectionManager cm;
private int numOfThreads = 2;
public File getOutputFile() {
return outputFile;
}
public void setOutputFile(File outputFile) {
this.outputFile = outputFile;
}
private File outputFile;
public FileDownloader(String _url) {
this.url = _url;
}
public void execute() throws IOException {
// 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。
Connection conn = null;
try {
// 针对每个线程,重新打开一个连接
conn = cm.open(this.url);
int length = conn.getContentLength();
System.err.println("Total Length:"+length);
int threadSize = length / numOfThreads;
// int remainSize = length % numOfThreads;
int threadCount = 0;
ExecutorService fixedThreadPool = Executors.newFixedThreadPool(numOfThreads);
DownloadThread[] dtArr = new DownloadThread[numOfThreads];
for (int i = 0; i < numOfThreads-1; i++) {
conn = cm.open(this.url);
System.err.println("Thread "+threadCount++);
dtArr[i] = new DownloadThread(conn, i * threadSize, (i + 1) * threadSize - 1);
fixedThreadPool.submit(dtArr[i]);
}
conn = cm.open(this.url);
dtArr[numOfThreads-1] = new DownloadThread(conn,(numOfThreads-1) * threadSize, length - 1);
fixedThreadPool.submit(dtArr[numOfThreads-1]);
fixedThreadPool.shutdown();
// 提交之后,等到 365天
fixedThreadPool.awaitTermination(365, TimeUnit.DAYS);
// 合并所有文件
FileOutputStream fos = new FileOutputStream(outputFile);
for(DownloadThread curDt:dtArr){
FileInputStream fis = new FileInputStream(curDt.getCurTmpFile());
byte[] bufferedByteArr = new byte[1024*8];
int readSize;
while((readSize=fis.read(bufferedByteArr))!=-1){
fos.write(bufferedByteArr, 0, readSize);
}
fis.close();
}
fos.close();
listener.notifyFinished();
} catch (ConnectionException e) {
e.printStackTrace();
} catch (InterruptedException ex) {
Logger.getLogger(FileDownloader.class.getName()).log(Level.SEVERE, null, ex);
} catch (FileNotFoundException ex) {
Logger.getLogger(FileDownloader.class.getName()).log(Level.SEVERE, null, ex);
} 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;
}
}