c# - How to split file into parts and download -
i'm working on split downloader c#. downloading fine (so logic working) problem whatever file downloads corrupts. have no idea on how fix it. here's code:
private void mergeclean() { const int chunksize = 1 * 1024; // 2kb using (var output = file.create("output.jpg")) { foreach (var file in files) { using (var input = file.openread(file)) { var buffer = new byte[chunksize]; int bytesread; while ((bytesread = input.read(buffer, 0, buffer.length)) > 0) { output.write(buffer, 0, bytesread); } } } } foreach (var file in files) { file.delete(file); } } private void savefilestream(string path, stream stream) { var filestream = new filestream(path, filemode.create, fileaccess.write); stream.copyto(filestream); filestream.dispose(); } public void splitdownload(string url) { system.net.webrequest req = system.net.httpwebrequest.create(url); req.method = "head"; system.net.webresponse resp = req.getresponse(); var responselength = double.parse(resp.headers.get("content-length")); var partsize = math.ceiling(responselength / 10); var previous = 0; (int = (int)partsize; <= responselength; = + (int)partsize) { thread t = new thread(() => download(url, previous, i)); t.start(); t.join(); previous = i; } mergeclean(); } private void download(string url, int start, int end) { console.writeline(string.format("{0},{1}", start, end)); httpwebrequest myhttpwebrequest = (httpwebrequest)webrequest.create(url); myhttpwebrequest.addrange(start, end); httpwebresponse myhttpwebresponse = (httpwebresponse)myhttpwebrequest.getresponse(); stream streamresponse = myhttpwebresponse.getresponsestream(); string name = generatetempname(); savefilestream(name, streamresponse); files.add(name); } here example of does:
updated code:
static string generatetempname(int start) { string name = string.format("{0:d6}.tmp", start); return name; } static public list<string> files = new list<string>(); static private void mergeclean() { files.sort(); const int chunksize = 1 * 1024; // 2kb using (var output = file.create("output.jpg")) { foreach (var file in files) { using (var input = file.openread(file)) { var buffer = new byte[chunksize]; int bytesread; while ((bytesread = input.read(buffer, 0, buffer.length)) > 0) { output.write(buffer, 0, bytesread); } } } } foreach (var file in files) { file.delete(file); } }
you need recombine file pieces in correct order - current code create random file names , if items added list of files added in random order due unpredictable time when segment download finishes.
possible fix: use block start offset part of file name string name = string.format("file{0:d6}.tmp", start) , sort files name before combining them back.
note {0:d6} formatting used pad index 0 allow sorting name easier , avoid need natural sort code.
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