I have set buffer size to 2M, but the result of "read.length:" is always <= 2048 on Android 5.0+. Why?
is = connection.getInputStream();
byte[] buffer = new byte[1024 * 1024 * 2];
int length = -1;
while ((length = is.read(buffer)) != -1) {
Log.d("read.length:"+length);
}
Related
We are developing a POS APP using xamarin.forms, in that we need to print the receipt to an esc/pos thermal printer connected via LAN.
We have multi language support with the App, printing multiple language with the esc/pos commands by changing code page works perfectly.
But its working for some supported language only, for other language its printing garbage characters(unreadable ones).
so we thought of creating a pdf for the receipt and print that one. we tried to create the pdf and then convert to bitmap and then send to the printer by using esc pos commands, but its not printing anything.
public BitImage(String filename)
{
Java.IO.File file = new Java.IO.File(filename);
var pdfRenderer = new PdfRenderer(ParcelFileDescriptor.Open(file, ParcelFileMode.ReadOnly));
PdfRenderer.Page page = pdfRenderer.OpenPage(0);
Bitmap bmp = Bitmap.CreateBitmap(page.Width, page.Height, Bitmap.Config.Argb8888);
page.Render(bmp, null, null, PdfRenderMode.ForPrint);
load(bmp);
}
private void load(Bitmap bmp)
{
int w = bmp.Width;
int h = bmp.Height;
int bw = (w + 7) / 8;
if (bw > 255)
bw = 255;
int bh = h / 8;
if (bh > 24)
{
bh = 24;
}
initData(bw * 8, bh * 8);
for (int y = 0; y < h; y++)
{
for (int x = 0; x < w; x++)
{
if (bmp.GetPixel(x, y) == Color.Black)
setPixel(x, y);
}
}
}
private void initData(int w, int h)
{
width = w;
height = h;
pitch = h / 8;
data = new byte[w * pitch];
}
private void setPixel(int x, int y)
{
if (x >= width || y >= height)
{
return;
}
int mask = (0x0080 >> (y % 8));
data[(x * pitch) + (y / 8)] |= (byte)mask;
}
public void PrintData()
{
byte[] CMD_INIT = { 0x1B, 0x40 };
byte[] CMD_UPLOAD_IMAGE = { 0x1D, 0x2A, 0, 0 };
byte[] CMD_PRINT_IMAGE = { 0x1D, 0x2F, 0 };
byte[] CMD_CUT = { 0x1D, 0x56, 0x01 };
CMD_UPLOAD_IMAGE[2] = (byte)(width / 8);
CMD_UPLOAD_IMAGE[3] = (byte)(height / 8);
#region Print Via Lan
Socket pSocket = new Socket(SocketType.Stream, ProtocolType.IP);
pSocket.SendTimeout = 1500;
pSocket.Connect("192.168.15.168", 9100);
pSocket.Send(CMD_INIT);
pSocket.Send(CMD_UPLOAD_IMAGE);
pSocket.Send(data);
pSocket.Send(CMD_PRINT_IMAGE);
pSocket.Send(CMD_CUT);
pSocket.Close();
#endregion
}
Please help me, whether i am doing it in correct way?
or is there any better way to do the same?
You can use libraries like SkiaSharp to make Image/PDF from your data in any language and print them properly using any printer.
I've created a sample to demonstrate how to print images properly with ESC\POS printers in C#: GitHub code repo
I tried to split large file into small 4KB chunks and send each chunks to oracle cloud but request is aborting. Please check the splitting code whether it is correct or not or am I doing wrong something else.
FileStream rdr = new FileStream(fileToUpload, FileMode.Open, FileAccess.Read);
byte[] inData = new byte[4096];
long chunkSize= rdr.Length;
long chunkBytesToRead = chunkSize;
using (Stream reqStream = request.GetRequestStream())
{
while (rdr.Position < rdr.Length)
{
int chunkBytesRead = 0;
int maxread = 4096;
while (chunkBytesRead < chunkSize)
{
int bytesRead = rdr.Read(inData,0,maxread);
if (bytesRead == 0)
{
break;
}
reqStream.Write(inData, 0, bytesRead);
chunkBytesToRead -= bytesRead;
if (chunkBytesToRead < 4096)
maxread = (int)chunkBytesToRead;
chunkBytesRead += bytesRead;
}
}
reqStream.Close();
}
I've got the following function to make a conversion from a Hex String to a Byte array. Then, I calculate the Checksum:
private String CalcChecksum (String message) {
/**Get string's bytes*/
//byte[] bytes = DatatypeConverter.parseHexBinary(message.replaceAll("\\s","")).getBytes();
message = message.replaceAll("\\s","");
byte[] bytes = hexToByteArray(message);
byte b_checksum = 0;
for (int byte_index = 0; byte_index < bytes.length; byte_index++) {
b_checksum += bytes[byte_index];
}
int d_checksum = b_checksum; //Convert byte to int(2 byte)
int c2_checksum = 256 - d_checksum; //Hacer complemento a 2
String hexString = Integer.toHexString(c2_checksum); //Convertir el entero (decimal) a hexadecimal
return hexString;
}
public static byte[] hexToByteArray(String s) {
int len = s.length();
byte[] data = new byte[len / 2];
for (int i = 0; i < len; i += 2) {
data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4) + Character.digit(s.charAt(i+1), 16));
}
return data;
}
Making some test, for example for the hex value "e0", the hexToByteArray is getting the value "-32". So the final returning value in the CalcChecksum is "17a".
What I need is to get unsigned values in the hexToByteArray function. This is because i need to send the Checksum in a hexString to a MCU where the Checksum is calculated with unsigned values, so isntead of get the "-32" value, it gets "224" and the final hex value is "7a" instead of "17a".
i think that doing some kind of conversion like when the byte result is a negative value, do something like 255 + "negative value" + 1. This will convert "-32" into "224".
The problem is that i'm trying to do it, but i'm having some errors making the conversions between bytes, int, etc...
So, how could i do?
For the moment, I think that this can be the solution.
Just including in the CalcChecksum function the next code after int d_checksum = b_checksum;:
if (d_checksum < 0) {
d_checksum = 255 + d_checksum + 1;
}
I am facing an Issue while uploading file from a web page to server. It works fine for files upto 200 MB, but starts throwing out of memory exception.
Could you please help me
I have pasted the code below
private void UploadToServer(HttpPostedFile oHttpPostedFile)
{
string CalCheckSum = string.Empty;
try
{
string FileName = getFileName(oHttpPostedFile.FileName.Trim());
if (File.Exists(Server.MapPath("Upload") + "\\" + System.IO.Path.GetFileName(FileName)))
{
File.Delete(Server.MapPath("Upload") + "\\" + System.IO.Path.GetFileName(FileName));
}
string serverFilePath = Server.MapPath("Upload") + "\\" + System.IO.Path.GetFileName(FileName);
FileStream fs = new FileStream(serverFilePath, FileMode.CreateNew);
string strFileFormName = serverFilePath;
// Uri oUri = new Uri(strUrl);
// DFB: Upload goes into stream
Stream myStream = oHttpPostedFile.InputStream;
string _name = oHttpPostedFile.FileName;
string _contentType = oHttpPostedFile.ContentType;
// DFB: Create buffer for stream
Byte[] myBuffer;
myBuffer = new byte[10240];
if (myStream.Length == 0)
{
//Zero Bytes file Can not be processed
CalCheckSum = string.Empty;
return;
}
else if (myStream.Length > 10240)
myBuffer = new byte[10240];
else
myBuffer = new byte[myStream.Length];
StringBuilder filecontent = new StringBuilder();
int fileLength = (int)myStream.Length;
int length = (int)myStream.Length / myBuffer.Length + 1;
int lastPacketLength = (int)myStream.Length % 10240;
int count = 1;
while (myStream.Read(myBuffer, 0, myBuffer.Length) > 0)
{
if (count == length)
fs.Write(myBuffer, 0, lastPacketLength);
else
fs.Write(myBuffer, 0, myBuffer.Length);
count++;
}
fs.Close();
fs.Dispose();
myStream.Dispose();
myBuffer = null;
myStream = null;
FileStream fileStream = File.OpenRead(serverFilePath);
byte[] pbytCombinedArrays = new byte[fileLength];
int numBytesToRead = fileLength;
int numBytesRead = 0;
while (numBytesToRead > 0)
{
// Read may return anything from 0 to numBytesToRead.
int n = fileStream.Read(pbytCombinedArrays, numBytesRead, numBytesToRead);
// Break when the end of the file is reached.
if (n == 0)
break;
numBytesRead += n;
numBytesToRead -= n;
}
fileStream.Dispose();
fileStream.Close();
}
You get the exception because you are trying to allocate more memory than is allowed for the application. Web applications are generally limited to about 300 MB.
The solution would be to avoid reading the entire file into memory. It's simply too large for a web application to handle all at once.
In a conditionally compliant/general-purpose server, something likes this
#define HTTP_MSG_LEN_MAX = ??;
...
int read_request(sockfd, ...)
{
char *buf = malloc(sizeof(char) * http_msg_len_max + 1);
int read_total = 0;
int read_once = 0;
while (zStrFind(buf, "\r\n\r\n") != -1 && read_total < HTTP_MSG_LEN_MAX) {
read_once = read(sockfd, buf + read_total, HTTP_MSG_LEN_MAX - read_total);
if (read_once < 0) {
fprintf(stderr, "read failed: %s \n", strerror(errno));
free(buf);
return -1;
}
read_total += read_once;
}
...
return 0;
}
I already know maximum length of HTTP URI in request,
but what's the maximum length of an HTTP message?
RFC2616 doesn't mentions it.
There is no maximum length (per specification).