我在一个示例 java http 服务器和一个 .Net 客户端（在平板电脑上）上工作。使用我的 http 服务器，.Net 客户端必须能够下载文件。
它运行良好，但现在我必须能够在连接中断后恢复下载。
这里有一些代码：
Java 服务器：（它在单独的线程中启动，因此是 run 方法）。
public void run() {
try {
server = com.sun.net.httpserver.HttpServer.create(
new InetSocketAddress(
portNumber), this.maximumConnexion);
server.setExecutor(executor);
server.createContext("/", new ConnectionHandler(this.rootPath));
server.start();
} catch (IOException e1) {
//For debugging
e1.printStackTrace();
}
}
我的 HttpHandler ：（仅处理 GET 请求的部分）
/**
* handleGetMethod : handle GET request. If the file specified in the URI is
* available, send it to the client.
*
* @param httpExchange
* @throws IOException
*/
private void handleGetMethod(HttpExchange httpExchange) throws IOException {
File file = new File(this.rootPath + this.fileRef).getCanonicalFile();
if (!file.isFile()) {
this.handleError(httpExchange, 404);
} else if (!file.getPath().startsWith(this.rootPath.replace('/', '\\'))) { // windows work with anti-slash!
// Suspected path traversal attack.
System.out.println(file.getPath());
this.handleError(httpExchange, 403);
} else {
//Send the document.
httpExchange.sendResponseHeaders(200, file.length());
System.out.println("file length : "+ file.length() + " bytes.");
OutputStream os = httpExchange.getResponseBody();
FileInputStream fs = new FileInputStream(file);
final byte[] buffer = new byte[1024];
int count = 0;
while ((count = fs.read(buffer)) >= 0) {
os.write(buffer, 0, count);
}
os.flush();
fs.close();
os.close();
}
}
现在我的 .Net 客户端：（简化）
try{
Stream response = await httpClient.GetStreamAsync(URI + this.fileToDownload.Text);
FileSavePicker savePicker = new FileSavePicker();
savePicker.SuggestedStartLocation = PickerLocationId.DocumentsLibrary;
// Dropdown of file types the user can save the file as
savePicker.FileTypeChoices.Add("Application/pdf", new List<string>() { ".pdf" });
// Default file name if the user does not type one in or select a file to replace
savePicker.SuggestedFileName = "new doc";
StorageFile file = await savePicker.PickSaveFileAsync();
if (file != null)
{
const int BUFFER_SIZE = 1024*1024;
using (Stream outputFileStream = await file.OpenStreamForWriteAsync())
{
using (response)
{
var buffer = new byte[BUFFER_SIZE];
int bytesRead;
do
{
bytesRead = response.Read(buffer, 0, BUFFER_SIZE);
outputFileStream.Write(buffer, 0, bytesRead);
} while (bytesRead > 0);
}
outputFileStream.Flush();
}
}
}
catch (HttpRequestException hre)
{ //For debugging
this.Display.Text += hre.Message;
this.Display.Text += hre.Source;
}
catch (Exception ex)
{
//For debugging
this.Display.Text += ex.Message;
this.Display.Text += ex.Source;
}
因此，要恢复下载，我想在 .Net 客户端部分使用一些搜索操作。但是每次我尝试类似的东西response.Seek(offset, response.Position);时，都会发生错误，通知 Stream 不支持查找操作。是的，它没有，但是我如何指定（在我的服务器端）使用可搜索流？HttpExchange.setStreams 方法有用吗？或者，我不需要修改流而是配置我的 HttpServer 实例？
谢谢。