文件从 PC 下载到 Android 设备 - OutputStream write() 卡住大文件

Question

我正在尝试将文件从 PC 下载到 Android 设备（模拟器或物理设备）

中小型文件一切正常，但是当我尝试发送大于 10Mb 的文件时，服务器永远不会到达此语句 out2.println("ready");，因此客户端挂起等待来自服务器的 "ready"
似乎服务器卡在这个：os.write(bytearray, 0, bytearray.length);

到目前为止，我已经在模拟器上尝试过了，我将很快报告真实设备上的结果

这是我的客户端部分，在 Android 应用程序中：Android 客户端向服务器发送“下载”字符串，然后从服务器接收“就绪”回复，并开始从 InputStream 读取文件

int filesize = 2022386;
int bytesRead;
int currentTot = 0;

Socket socket1 = new Socket("172.16.6.119", 50001); //data line
Socket socket2 = new Socket("172.16.6.119", 50001); //control line

BufferedReader in2 = new BufferedReader(new InputStreamReader(socket2.getInputStream()));  
PrintWriter out2 = new PrintWriter(socket2.getOutputStream(), true);

out2.println("download:"); //control line

String usrtxt = in2.readLine();

if(usrtxt.substring(0,5).equals("ready")) //control line
                {
                    byte [] bytearray = new byte [filesize];

                    InputStream is = socket1.getInputStream(); //data line
                    FileOutputStream fos = new FileOutputStream(Environment.getExternalStorageDirectory().toString() + "/sunset.jpg");
                    BufferedOutputStream bos = new BufferedOutputStream(fos);
                    bytesRead = is.read(bytearray,0,bytearray.length);
                    currentTot = bytesRead;

                    Log.e("DOWNLOAD", "init value: bytesread = " + Integer.toString(bytesRead));

                    do {
                    bytesRead =
                    is.read(bytearray, currentTot, (bytearray.length-currentTot)); //<--does not pull data (WHY?)

                    Log.e("DOWNLOAD", "bytesread = " + Integer.toString(bytesRead));

                    if(bytesRead >= 0) currentTot += bytesRead;
                    } while(bytesRead > -1);

                    out1.println("finished:");

                    bos.write(bytearray, 0 , currentTot);

                    Log.e("DOWNLOAD", Integer.toString(currentTot));
                    bos.flush();
                    bos.close();
                    socket1.close(); socket2.close();       

                }

这是我的服务器代码：它接受来自客户端的连接，然后从客户端接收“下载”字符串，回复“就绪”，然后将文件放入 OutputStream

while (true) {

                final Socket socket = serverSocket.accept();  //data line
                final Socket socket2= serverSocket.accept();  //control line          

                BufferedReader in2 = new BufferedReader(new InputStreamReader(socket2.getInputStream()));  
                PrintWriter out2 = new PrintWriter(socket2.getOutputStream(), true);

                String usrtxt = in2.readLine(); //control line

                if(usrtxt.substring(0,8).equals("download"))
                {
                System.out.println("accepted download request. sending file");  

                File transferFile = new File("sunset.jpg"); 

                byte[] bytearray = new byte[(int)transferFile.length()];
                FileInputStream fin = new FileInputStream(transferFile);
                BufferedInputStream bin = new BufferedInputStream(fin);
                bin.read(bytearray, 0, bytearray.length);

                OutputStream os = socket.getOutputStream();
                os.write(bytearray, 0, bytearray.length); //data line


                os.flush();
                os.close();

                out2.println("ready"); //control line


                socket.close(); socket2.close();
                bin.close(); fin.close();


                System.out.println("file transfer complete");

                }//end if           

            }//end while

Answer 1

这不是复制流的方法。它假设了太多可能不正确的事情。

Java中的规范方式如下：

byte[] buffer = new byte[8192];  // or whatever you like, anything above zero. Note that it doesn't have to be the size of the file
int count;
while ((count = in.read(buffer)) > 0)
{
    out.write(buffer, 0, count);
}

如果您事先知道长度并且想在之后保持套接字打开，请通过“total += count;”跟踪到目前为止传输的字节数；在循环内的读取调用之后，将读取调用更改为read(buffer, 0, length-total > buffer.length ? buffer.length : (int)(length-total))。