package com.coderising.download;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import com.coderising.download.api.Connection;
import com.coderising.download.api.ConnectionException;
import com.coderising.download.api.ConnectionManager;
import com.coderising.download.api.DownloadListener;
public class FileDownloader {
String url;
DownloadListener listener;
ConnectionManager cm;
private static int DOWNLOAD_SIZE_PER_THREAD = 1024*1000;
private String destFilePath;
public FileDownloader(String _url) {
this.url = _url;
}
public FileDownloader(String _url,String destFilePath) {
this.url = _url;
this.destFilePath = destFilePath;
}
public void execute(){
// 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 {
conn = cm.open(this.url);
int length = conn.getContentLength();
System.out.println("GetLength ="+length);
File dest = new File(destFilePath);
dest.createNewFile();
//fill the file with byte array to ensure the size
// byte[] ba = new byte[length];
// FileOutputStream fos = new FileOutputStream(dest);
// fos.write(ba);
// fos.flush();
// fos.close();
ArrayList<DownloadThread> threadPool = new ArrayList<DownloadThread>();
int numOfThread = length/DOWNLOAD_SIZE_PER_THREAD;
if(length%DOWNLOAD_SIZE_PER_THREAD!=0)
{
numOfThread++;
}
for(int i=0;i<numOfThread;i++){
int startPos = i*DOWNLOAD_SIZE_PER_THREAD;
int endPos = (i+1)*DOWNLOAD_SIZE_PER_THREAD-1;
if(endPos>length-1)
{
endPos = length-1;
}
DownloadThread t = new DownloadThread(cm.open(url),startPos,endPos,destFilePath);
t.setName("downloadThread_"+i);
System.out.println("Initializing Thread:"+t.getName());
threadPool.add(t);
t.start();
}
//pooling
boolean flag;
do{
Iterator<DownloadThread> it = threadPool.iterator();
flag=true;
DownloadThread t;
while(it.hasNext()){
t = it.next();
System.out.println("Thread ="+t.getName()+" has completed?"+t.isFinished());
flag = flag && t.isFinished();
}
if(!flag){
System.out.println("=====================AllCompleted="+flag);
Thread.sleep(10*1000);
continue;
}
}while(!flag);
} catch (Exception e) {
throw new RuntimeException("Error occured during download,",e);
}finally{
if(conn != null){
conn.close();
}
}
getListener().notifyFinished();
}
public void setListener(DownloadListener listener) {
this.listener = listener;
}
public void setConnectionManager(ConnectionManager ucm){
this.cm = ucm;
}
public DownloadListener getListener(){
return this.listener;
}
}