package com.coderising.download;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.net.URL;
import java.util.UUID;
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 {
private String url;
private String localPath = "";
private DownloadListener listener;
private ConnectionManager cm;
public FileDownloader(String _url) {
this.url = _url;
}
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。
try {
int length = cm.open(url).getContentLength();
RandomAccessFile tempFile = CreateTempFile(localPath,cm.open(url));
int step = length / 4;
DownloadThread downloadThread0 = new DownloadThread(cm.open(this.url,0,step-1),tempFile,"downLoad_Thread0");
DownloadThread downloadThread1 = new DownloadThread(cm.open(this.url,step,2*step-1),tempFile,"downLoad_Thread1");
DownloadThread downloadThread2 = new DownloadThread(cm.open(this.url,2*step,3*step-1),tempFile,"downLoad_Thread2");
DownloadThread downloadThread3 = new DownloadThread(cm.open(this.url,3*step,length),tempFile,"downLoad_Thread3");
downloadThread0.start();
downloadThread1.start();
downloadThread2.start();
downloadThread3.start();
while(true) {
if (!(downloadThread0.isAlive()||downloadThread1.isAlive()||downloadThread2.isAlive()||downloadThread3.isAlive())) {
tempFile.close();
this.listener.notifyFinished();
break;
}
}
} catch (ConnectionException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
private RandomAccessFile CreateTempFile(String path,Connection _conn) {
String tempFileName = UUID.randomUUID().toString() + ".jpg";
RandomAccessFile randomAccessFile = null;
try {
randomAccessFile = new RandomAccessFile(path + File.separator +tempFileName,"rw");
randomAccessFile.setLength(_conn.getContentLength());
} catch (FileNotFoundException e1) {
e1.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return randomAccessFile;
}
private boolean ChangeFileName(File _f,Connection _conn) {
String fileName = _conn.getURL().getFile().substring(url.lastIndexOf("/"));
return _f.renameTo(new File(_f.getAbsolutePath()+File.separator+fileName));
}
public void setListener(DownloadListener listener) {
this.listener = listener;
}
public void setConnectionManager(ConnectionManager ucm){
this.cm = ucm;
}
public DownloadListener getListener(){
return this.listener;
}
public String getLocalPath() {
return localPath;
}
public void setLocalPath(String localPath) {
this.localPath = localPath;
}
}