C# Http方式下载文件到本地类

时间:2023-03-08 23:01:47
C# Http方式下载文件到本地类

直接上代码:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Net; namespace ConsoleTest
{
class HttpDldFile
{
/// <summary>
/// Http方式下载文件
/// </summary>
/// <param name="url">http地址</param>
/// <param name="localfile">本地文件</param>
/// <returns></returns>
public bool Download(string url,string localfile)
{
bool flag = false;
long startPosition = ; // 上次下载的文件起始位置
FileStream writeStream; // 写入本地文件流对象 long remoteFileLength = GetHttpLength(url);// 取得远程文件长度
System.Console.WriteLine("remoteFileLength=" + remoteFileLength);
if (remoteFileLength==)
{
System.Console.WriteLine("远程文件不存在.");
return false;
} // 判断要下载的文件夹是否存在
if (File.Exists(localfile))
{ writeStream = File.OpenWrite(localfile); // 存在则打开要下载的文件
startPosition = writeStream.Length; // 获取已经下载的长度 if (startPosition >= remoteFileLength)
{
System.Console.WriteLine("本地文件长度" + startPosition + "已经大于等于远程文件长度" + remoteFileLength);
writeStream.Close(); return false;
}
else
{
writeStream.Seek(startPosition, SeekOrigin.Current); // 本地文件写入位置定位
}
}
else
{
writeStream = new FileStream(localfile, FileMode.Create);// 文件不保存创建一个文件
startPosition = ;
} try
{
HttpWebRequest myRequest = (HttpWebRequest)HttpWebRequest.Create(url);// 打开网络连接 if (startPosition > )
{
myRequest.AddRange((int)startPosition);// 设置Range值,与上面的writeStream.Seek用意相同,是为了定义远程文件读取位置
} Stream readStream = myRequest.GetResponse().GetResponseStream();// 向服务器请求,获得服务器的回应数据流 byte[] btArray = new byte[];// 定义一个字节数据,用来向readStream读取内容和向writeStream写入内容
int contentSize = readStream.Read(btArray, , btArray.Length);// 向远程文件读第一次 long currPostion=startPosition; while (contentSize > )// 如果读取长度大于零则继续读
{
currPostion+=contentSize;
int percent = (int)(currPostion*/ remoteFileLength);
System.Console.WriteLine("percent=" + percent + "%"); writeStream.Write(btArray, , contentSize);// 写入本地文件
contentSize = readStream.Read(btArray, , btArray.Length);// 继续向远程文件读取
} //关闭流
writeStream.Close();
readStream.Close(); flag = true; //返回true下载成功
}
catch (Exception)
{
writeStream.Close();
flag = false; //返回false下载失败
} return flag;
} // 从文件头得到远程文件的长度
private static long GetHttpLength(string url)
{
long length=; try
{
HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(url);// 打开网络连接
HttpWebResponse rsp = (HttpWebResponse)req.GetResponse(); if (rsp.StatusCode == HttpStatusCode.OK)
{
length = rsp.ContentLength;// 从文件头得到远程文件的长度
} rsp.Close();
return length;
}
catch(Exception e){
return length;
} }
}
}

调用:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text; namespace ConsoleTest
{
class Program
{
static void Main(string[] args)
{
HttpDldFile df = new HttpDldFile();
df.Download("http://files.cnblogs.com/files/xiandedanteng/Convertor20170624.zip","C:\\test\\Convertor20170624.zip");
}
}
}