i need a solution for reading a text file which was stored in internal storage.
i don't want to read it line by line. without use looping how to read a complete text file and store it into a string.
BufferedReader br;
String line;
String data = "";
// String text="";
try {
br = new BufferedReader(new FileReader(new File(Environment.getExternalStorageDirectory(), "queue_mgr.txt")));
while ((line = br.readLine()) != null) {
sb.append(line);
}
br.close();
}
You can use a large byte buffer and gain some efficiency:
try
{
InputStream in = new FileInputStream (from);
OutputStream out = new FileOutputStream (to);
// Transfer bytes from in to out
byte[] buf = new byte[1024 * 10]; // 5MB would be about 500 iterations
int len;
while ((len = in.read (buf)) > 0)
out.write (buf, 0, len);
in.close ();
out.close ();
}
}
catch (FileNotFoundException e)
{
...
}
catch (IOException e)
{
...
}
Related
I have a simulation program that needs to write certain results to a csv file very frequently during execution. I have found that there is something wrong with the printwriter which dramatically slows down running my program, as the output file is getting larger in size (near to 1 million rows). I doublt it's overwriting the entire file each time from the beginning, wheras I just need to append a single line at the bottom each time when it's being called. below is the code related to the writing fuctions.
one of the writing fuctions:
public void printHubSummary(Hub hub, String filePath) {
try {
StringBuilder sb = new StringBuilder();
String h = hub.getHub_code();
String date = Integer.toString(hub.getGs().getDate());
String time = hub.getGs().getHHMMFromMinute(hub.getGs().getClock());
String wgt = Double.toString(hub.getIb_wgt());
sb.append(h+","+date+","+time+","+wgt);
// System.out.println("truck print line: " + sb);
FileWriter.writeFile(sb.toString(),filePath);
}
catch (Exception e) {
System.out.println("Something wrong when outputing truck summary file!");
e.printStackTrace();
}
}
the file writer code: (should be where the problem is!)
public static boolean writeFile(String newStr, String filename) throws IOException {
boolean flag = false;
String filein = newStr + "\r\n";
String temp = "";
FileInputStream fis = null;
InputStreamReader isr = null;
BufferedReader br = null;
FileOutputStream fos = null;
PrintWriter pw = null;
try {
File file = new File(filename);
fis = new FileInputStream(file);
isr = new InputStreamReader(fis);
br = new BufferedReader(isr);
StringBuffer buf = new StringBuffer();
for (int j = 1; (temp = br.readLine()) != null; j++) {
buf = buf.append(temp);
buf = buf.append(System.getProperty("line.separator"));
}
if (buf.length() > 0 && buf.charAt(0) == '\uFEFF') {
buf.deleteCharAt(0);
}
buf.append(filein);
fos = new FileOutputStream(file);
byte[] unicode = {(byte)0xEF, (byte)0xBB, (byte)0xBF};
fos.write(unicode);
pw = new PrintWriter(fos);
pw.write(buf.toString().toCharArray());
pw.flush();
flag = true;
} catch (IOException e1) {
throw e1;
} finally {
if (pw != null) {
pw.close();
}
if (fos != null) {
fos.close();
}
if (br != null) {
br.close();
}
if (isr != null) {
isr.close();
}
if (fis != null) {
fis.close();
}
}
return flag;
}
An update on code modification. I have freezed the operations of repeatitively overwrting the entire file. It appears to solve the problem, but writing for sometime it's slowed down as well. Is it the best arrangement for wrting very large file? what other modifications can be done to make it even more efficient?
public static boolean writeFile1(String newStr, String filename) throws IOException {
boolean flag = false;
String filein = newStr + "\r\n";
String temp = "";
FileInputStream fis = null;
InputStreamReader isr = null;
BufferedReader br = null;
FileOutputStream fos = null;
PrintWriter pw = null;
try {
File file = new File(filename);
fis = new FileInputStream(file);
isr = new InputStreamReader(fis);
br = new BufferedReader(isr);
StringBuffer buf = new StringBuffer();
// for (int j = 1; (temp = br.readLine()) != null; j++) {
// buf = buf.append(temp);
// buf = buf.append(System.getProperty("line.separator"));
// }
// if (buf.length() > 0 && buf.charAt(0) == '\uFEFF') {
// buf.deleteCharAt(0);
// }
buf.append(filein);
fos = new FileOutputStream(file,true);
byte[] unicode = {(byte)0xEF, (byte)0xBB, (byte)0xBF};
fos.write(unicode);
pw = new PrintWriter(fos);
pw.write(buf.toString().toCharArray());
pw.flush();
flag = true;
} catch (IOException e1) {
throw e1;
} finally {
if (pw != null) {
pw.close();
}
if (fos != null) {
fos.close();
}
if (br != null) {
br.close();
}
if (isr != null) {
isr.close();
}
if (fis != null) {
fis.close();
}
}
return flag;
}
Provide a second argument to the FileOutputStream constructor to specify whether or not to use append mode, which will add to the end of the file rather than overwriting it.
fos = new FileOutputStream(file, true);
Alternatively, you could create a single static PrintWriter in append mode, which will probably be faster as it reduces garbage collection.
Use the Files / Path / Java NIO2 which is richer: the code below would need Java 7 at least.
Path path = Paths.get(filename);
try (BufferedWriter bw = Files.newBufferedWriter(
path, StandardCharsets.UTF_8, StandardOpenOption.APPEND, StandardOpenOption.CREATE, StandardOpenOption.WRITE)) {
bw.append(filein);
bw.newLine();
}
Your cue here is the StandardOpenOption.
You will probably have to do some additional code before to write the Unicode part (and fix the StandardCharsets.UTF_8):
if (Files.notExists(path)) {
Files.write(path, new byte[] {(byte)0xEF, (byte)0xBB, (byte)0xBF});
}
Also, try to not use StringBuffer in a local method, use StringBuilder: you don't need synchronisation most of the time.
If I have my code this way round the PDF say's its invalid and cannot be opened, but if I swap them and have B before A it works fine? why is this and what would I have to do to get it working? TIA
InputStream in = new BufferedInputStream(conn.getInputStream());
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
//A
String line = "";
StringBuilder builder = new StringBuilder();
try {
while ((line = reader.readLine()) != null) {
builder.append(line);
}
} catch (IOException e) {
e.printStackTrace();
}
//B
File directory = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
File outputFile = new File(directory, "goo.pdf");
FileOutputStream fos = null;
try {
fos = new FileOutputStream(outputFile);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
byte[] buffer = new byte[1024];
int len1 = 0;//init length
while (true) {
try {
if (!((len1 = in.read(buffer)) != -1)) break;
} catch (IOException e) {
e.printStackTrace();
}
try {
fos.write(buffer, 0, len1);
} catch (IOException e) {
e.printStackTrace();
}
}
An InputStream can only be read once.
In 'A', the stream is read and the contents are put in a StringBuilder.
In 'B', the stream (now empty) is read and piped to a file.
By having A first, the output file will always be empty.
Simply remove A as it's not doing anything for you here.
I need to download a .txt file from a website, the problem is the downloaded file doesn't respect the same line wrapping as the original file.
File:
Word1
Word2
Word3
File downloaded:
Word1Word2Word3
I use this method to download (this isn't mine) :
#Override
protected String doInBackground(String... f_url) {
int count;
try {
URL url = new URL(f_url[0]);
URLConnection conection = url.openConnection();
conection.connect();
int lenghtOfFile = conection.getContentLength();
InputStream input = new BufferedInputStream(url.openStream(), 8192);
OutputStream output = new FileOutputStream( MegaMethods.FolderPath+"downloadedfile.txt");
byte data[] = new byte[1024];
long total = 0;
while ((count = input.read(data)) != -1) {
total += count;
publishProgress(""+(int)((total*100)/lenghtOfFile));
output.write(data, 0, count);
}
output.flush();
output.close();
input.close();
} catch (Exception e) {
Log.e("Error: ", e.getMessage());
}
return null;
}
Try using a BufferedReader to read it in something like
BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String line = null;
StringBuilder responseData = new StringBuilder();
while((line = in.readLine()) != null) {
responseData.append(line);
}
then output the lines as necessary. I'm no where near a station where I can test this so you might have to do some fiddling.
I want to read my data from my .txt file into a ReaderClass in android, fields are seperated by ";"
---- here is my solution of my last post:
public void cut()
{
try{
InputStream input =context.getResources().openRawResource(R.raw.textfile);
BufferedReader br = null;
br=new BufferedReader(new InputStreamReader(input,"iso-8859-1"));
String line = null;
while ((line = br.readLine()) != null) {
String[] decoupage= line.split(";");
String titre=decoupage[0];
String description=decoupage[1];
String reponse=decoupage[2];
String explication=decoupage[3];
String categorie=decoupage[4];
String etat=decoupage[5];
//test Logcat
Log.d("information ", " buffer");
Log.i("titre : ",titre);
Log.i("description : ",description);
Log.i("reponse : ",reponse);
Log.i("explication : ",explication);
Log.i("categorie : ",categorie);
Log.i("etat : ",etat);
}
in.close();
}catch (Exception e){
System.err.println("Error: " + e.getMessage());
System.err.println("\n File not found");
}
//end
}
FileInputStream fis;
fis = openFileInput("sample.txt");
StringBuffer Content = new StringBuffer("");
byte[] buffer = new byte[1024];
int length;
while ((length = fis.read(buffer)) != -1) {
Content.append(new String(buffer));
}
you will get entire content in a string buffer ,convert it into string, then you can apply yourString.split(";") to get all values which you can keep in some array.
I have a webapplication which allows to upload binary files. I have to parse them and save the content 1:1 into a String and then into the database.
When I use uuencode on a unix machine to encode the binary file, then it works. Is there a way to do this automatically in java?
if (isMultipart) {
//Create a new file upload handler
ServletFileUpload upload = new ServletFileUpload();
//Parse the request
FileItemIterator iter = upload.getItemIterator(request);
while (iter.hasNext()) {
FileItemStream item = iter.next();
String name = item.getFieldName();
InputStream stream = item.openStream();
if (!item.isFormField()) {
BufferedReader reader = new BufferedReader(new InputStreamReader(stream));
String line;
licenseString = "";
while ((line = reader.readLine()) != null) {
System.out.println(line);
// Generate License File
licenseString += line + "\n";
}
}
}
session.setAttribute("licenseFile", licenseString);
System.out.println("adding licensestring to session. ");
}
It works of course for all non-binary files uploaded. How can I extend it to support binary files?
// save to file
// =======================================
InputStream is = new BufferedInputStream(item.openStream());
BufferedOutputStream output = null;
try {
output = new BufferedOutputStream(new FileOutputStream("temp.txt", false));
int data = -1;
while ((data = is.read()) != -1) {
output.write(data);
}
} finally {
is.close();
output.close();
}
// read content of file
// =======================================
System.out.println("content of file:");
try {
FileInputStream fstream = new FileInputStream("temp.txt");
DataInputStream in = new DataInputStream(fstream);
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String line;
licenseString = "";
String strLine;
while ((strLine = br.readLine()) != null) {
System.out.println(javax.xml.bind.DatatypeConverter.printBase64Binary(strLine.getBytes()));
licenseString += javax.xml.bind.DatatypeConverter.printBase64Binary(strLine.getBytes()) + "\n";
}
} catch (Exception e) {
System.err.println("Error: " + e.getMessage());
}
You could use the commons_fileupload lib (check it here : org.apache.commons.fileupload.disk.DiskFileItem is not created properly?)
The doc is here : http://commons.apache.org/fileupload/using.html
Your case is pretty well explained on the official website.
A Better way would be to write the upload to a temporary file and then handle it from there:
if (!item.isFormField()) {
InputStream stream = new BufferedInputStream(item.getInputStream());
BufferedOutputStream output = null;
try {
output = new BufferedOutputStream(new FileOutputStream(your_temp_file, false));
int data = -1;
while ((data = input.read()) != -1) {
output.write(data);
}
} finally {
input.close();
output.close();
}
}
now you have a temporary file, which is the same as the uploaded file, you can do your 'other' calculations from there.