文件的分割下载
HttpFile类：
public class HttpFile
{
public Form1 formm;
public int threadh;//线程代号
public string filename;//文件名
public string strUrl;//接收文件的URL
public FileStream fs;
public HttpWebRequest request;
public System.IO.Stream ns;
public byte[] nbytes;//接收缓冲区
public int nreadsize;//接收字节数
public HttpFile(Form1 form, int thread)//构造方法
{
formm = form;
threadh = thread;
}
public HttpFile()//析构方法
{
formm.Dispose();
}
public void receive()//接收线程
{
filename = formm.filenamew[threadh];
strUrl = formm.strurl;
ns = null;
nbytes = new byte[512];
nreadsize = 0;
fs = new FileStream(filename, System.IO.FileMode.Create);
try
{
request = (HttpWebRequest)HttpWebRequest.Create(strUrl);
//接收的起始位置及接收的长度
request.AddRange(formm.filestartw[threadh],
formm.filestartw[threadh] + formm.filesizew[threadh]);
ns = request.GetResponse().GetResponseStream();//获得接收流
nreadsize = ns.Read(nbytes, 0, 512);
while (nreadsize > 0)
{
fs.Write(nbytes, 0, nreadsize);
nreadsize = ns.Read(nbytes, 0, 512);
}
fs.Close();
ns.Close();
}
catch (Exception er)
{
string message=(er.Message);
fs.Close();
}
formm.threadw[threadh] = true;
}
}
窗体代码：
public bool[] threadw; //每个线程结束标志
public string[] filenamew;//每个线程接收文件的文件名
public int[] filestartw;//每个线程接收文件的起始位置
public int[] filesizew;//每个线程接收文件的大小
public string strurl;//接受文件的URL
public bool hb;//文件合并标志
public int thread;//进程数
/// <summary>
/// 下载
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void button1_Click(object sender, EventArgs e)
{
lblMessage.Text = "正在下载...";
strurl = textBox2.Text.Trim().ToString();
WebRequest request;
long filesize = 0;
try
{
request = (HttpWebRequest)HttpWebRequest.Create(strurl);
filesize = request.GetResponse().ContentLength;//取得目标文件的长度
request.Abort();
}
catch (Exception er)
{
MessageBox.Show(er.Message);
}
// 接收线程数
thread = Convert.ToInt32(textBox4.Text.Trim().ToString(), 10);
//根据线程数初始化数组
threadw = new bool[thread];
filenamew = new string[thread];
filestartw = new int[thread];
filesizew = new int[thread];
//计算每个线程应该接收文件的大小
int filethread = (int)filesize / thread;//平均分配
int filethreade = filethread + (int)filesize % thread;//剩余部分由最后一个线程完成
//为数组赋值
for (int i = 0; i < thread; i++)
{
threadw[i] = false;//每个线程状态的初始值为假
filenamew[i] = i.ToString() + ".dat";//每个线程接收文件的临时文件名
if (i < thread - 1)
{
filestartw[i] = filethread * i;//每个线程接收文件的起始点
filesizew[i] = filethread - 1;//每个线程接收文件的长度
}
else
{
filestartw[i] = filethread * i;
filesizew[i] = filethreade - 1;
}
}
//定义线程数组，启动接收线程
Thread[] threadk = new Thread[thread];
HttpFile[] httpfile = new HttpFile[thread];
for (int j = 0; j < thread; j++)
{
httpfile[j] = new HttpFile(this, j);
threadk[j] = new Thread(new ThreadStart(httpfile[j].receive));
threadk[j].Start();
}
//启动合并各线程接收的文件线程
Thread hbth = new Thread(new ThreadStart(hbfile));
hbth.Start();
}
/// <summary>
/// 合并的方法
/// </summary>
public void hbfile()
{
if (this.InvokeRequired)
{
while (true)//等待
{
hb = true;
for (int i = 0; i < thread; i++)
{
if (threadw[i] == false)//有未结束线程，等待
{
hb = false;
Thread.Sleep(100);
break;
}
}
if (hb == true)//所有线程均已结束，停止等待，
{
break;
}
}
FileStream fs;//开始合并
FileStream fstemp;
int readfile;
byte[] bytes = new byte[512];
fs = new FileStream(textBox3.Text.Trim().ToString(), System.IO.FileMode.Create);
for (int k = 0; k < thread; k++)
{
fstemp = new FileStream(filenamew[k], System.IO.FileMode.Open);
while (true)
{
readfile = fstemp.Read(bytes, 0, 512);
if (readfile > 0)
{
fs.Write(bytes, 0, readfile);
}
else
{
break;
}
}
fstemp.Close();
}
fs.Close();
this.lblMessage.Invoke(new ThreadStart(Show) );
}
}
private void Show()
{
lblMessage.Text = "下载完成。";
}