package com.coderising.download;
import com.coderising.download.api.Connection;
import com.coderising.download.api.ConnectionException;
import com.coderising.download.api.ConnectionManager;
import com.coderising.download.api.DownloadListener;
import com.coding.basic.Stack;
public class FileDownloader {
String url;
DownloadListener listener;
ConnectionManager cm;
// Use stack to check if all threads are finished
// When a thread is started, an empty Object will be pushed in this stack;
// when a thread is finished, an Object will be popped out.
private Stack mStack;
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
Connection conn = null;
try {
int length = 0;
int threadNum = 3;
mStack = new Stack();
DownloadThread.DownloadThreadListener dtListener = new DownloadThread.DownloadThreadListener() {
@Override
public void onFinished(Connection conn, int tag, boolean succeeded) {
System.out.println("Thread with tag " + tag + (succeeded?" succeeded":" failed") + " to download");
mStack.pop();
if (conn != null) {
conn.close();
}
if (mStack.isEmpty()) {
listener.notifyFinished();
}
}
};
for (int i = 0; i < threadNum; i++) {
conn = cm.open(this.url);
if (length == 0) {
length = conn.getContentLength();
}
mStack.push(new Object());
DownloadThread dt = new DownloadThread(conn,length*i/threadNum,length*(i+1)/threadNum - 1);
dt.setTagAndListener(i, dtListener);
dt.start();
System.out.println("DownloadThread with tag " + i + " created and started");
}
} catch (ConnectionException e) {
e.printStackTrace();
} 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;
}
}