I have some files i would like to convert to hex, alter, and then reverse again, but i have a problem trying to do jars, zips, and rars. It seems to only work on files containing normally readable text. I have looked all around but cant find anything that would allow jars or bats to do this correctly. Does anyone have an answer that does both? converts to hex then back again, not just to hex?
You can convert any file to hex. It's just a matter of obtaining a byte stream, and mapping every byte to two hexadecimal numbers.
Here's a utility class that lets you convert from a binary stream to a hex stream and back:
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.Writer;
public class Hex {
public static void binaryToHex(InputStream is, OutputStream os) {
Writer writer = new BufferedWriter(new OutputStreamWriter(os));
try {
int value;
while ((value = is.read()) != -1) {
writer.write(String.format("%02X", value));
}
writer.flush();
} catch (IOException e) {
System.err.println("An error occurred");
}
}
public static void hexToBinary(InputStream is, OutputStream os) {
Reader reader = new BufferedReader(new InputStreamReader(is));
try {
char buffer[] = new char[2];
while (reader.read(buffer) != -1) {
os.write((Character.digit(buffer[0], 16) << 4)
+ Character.digit(buffer[1], 16));
}
} catch (IOException e) {
System.err.println("An error occurred");
}
}
}
Partly inspired by this sample from Mykong and this answer.
Don't use a Reader to read String / char / char[], use an InputStream to read byte / byte[].
Related
I uploaded a html file from my D drive to an ORACLE database, now i am trying to retrieve the same file to another drive in my pc with a new name but i am not able to receive the exact same file, The code that i have used is listed below.
My question is how do i get the same copy of the file that i stored in my database.
import java.io.FileWriter;
import java.io.FileWriter;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
public class RBLOB {
public static void main(String args[])throws Exception
{
try(Connection con=DriverManager.getConnection("jdbc:oracle:thin:#localhost:1521:xe","hr","hr");)
{
PreparedStatement ps=con.prepareStatement("select * from players");
ResultSet rs=ps.executeQuery();
rs.next();
InputStream is= rs.getBinaryStream(2);
FileWriter fw=new FileWriter("C:\\Users\\y_san\\Desktop\\test.html");
while(is.read()!=-1)
{
fw.write(is.read());
System.out.println(is.read());
fw.flush();
}
}
catch(Exception ex)
{
System.out.println(ex.getMessage());
}
}
}
The bytes you read here
while(is.read()!=-1)
will never show in File or out as you already read the next byte to write it out.
while(is.read()!=-1) { // byte 1 read
fw.write(is.read()); // byte 2 read
System.out.println(is.read()); // byte 3 read
Try reading into a byte array and write out the number of bytes read like
byte [] buf = new byte [1024];
int len = is.read(buf);
while (len > 0){
fw.write (buf,0,len);
// more stuff
// read next chunk
len = is.read(buf);
}
This question already has answers here:
How to check if a generated zip file is corrupted?
(8 answers)
Closed 7 years ago.
I am trying to download a ZIP file from a http url connection. How do i confirm if the zip file is completely downloaded. Is there anyway i can get the end of zip file.
EOF will reach when stream return -1 (as mentioned by MadConan also). You need to read the data until
inputStream.read == -1
A simple example shown below:
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
public class ZipFileDownloader {
public static void downloadZipFile(String urlPath, String saveTo) {
try {
URLConnection connection = new URL(urlPath).openConnection();
InputStream in = connection.getInputStream();
FileOutputStream out = new FileOutputStream(saveTo + "myFile.zip");
byte[] b = new byte[1024];
int count;
while ((count = in.read(b)) > 0) {
out.write(b, 0, count);
}
out.flush();
out.close();
in.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
Hi i am trying to read a url where i am getting a string i am printing that string on console but i want to read that url as a byte by byte which i am not getting how can i read
Here is my ReadTextFromURL
import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
public class ReadTextFromURL {
public static void main(String[] args) {
try {
URL url = new URL("http://122.160.81.37:8080/mandim/MarketWise?m=agra");
ByteArrayOutputStream bais = new ByteArrayOutputStream();
BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));
String line;
int lin;
while ((lin = in.read()) != -1) {
System.out.println(lin);
}
in.close();
} catch (MalformedURLException e) {
System.out.println("Malformed URL: " + e.getMessage());
}catch (IOException e) {
System.out.println("I/O Error: " + e.getMessage());
}
}
}
desired output
धान~1325|चावल~2050|ज्वर~920|जौ~810|मकई~1280|गेहूँ~1420|जो~1050|बेजर~-|जय~800
getting output
2343
2366
2344
126
49
51
50
53
124
2330
2366
2357
2354
126
50
How can I get my desired output?
You can open the URL as InputStream and use the byte oriented method specifying an array of size equal to 1. Have a look to this page: http://docs.oracle.com/javase/7/docs/api/java/io/InputStream.html#read(byte[],%20int,%20int)
By the way, use the try-with-resource construct construct when working with streams:
byte oneSizeByteArray = new byte[1];
try (InputStream is = url.openStream()) {
is.read(oneSizeByteArray,0,1)
} catch (IOException ex) {
}
If you want to read bytes, don't use Readers. A Reader reads chars (not bytes). If you need to read bytes, use low-level input-output classes (InputStream/OutputStream).
I am attempting to take a pdf file and grab the text from it.
I found iText and have been using it and have had decent success. The one problem I have remaining are ligatures.
At first I noticed that I was simply missing characters. After doing some searches I came across this:
http://support.itextpdf.com/node/25
Once I knew that it was ligatures I was missing, I began to search for ways to solve the problem and haven't been able to come up with a solution yet.
Here is my code:
import com.itextpdf.text.Document;
import com.itextpdf.text.pdf.PdfImportedPage;
import com.itextpdf.text.pdf.PdfReader;
import com.itextpdf.text.pdf.parser.PdfTextExtractor;
import com.itextpdf.text.pdf.parser.SimpleTextExtractionStrategy;
import com.itextpdf.text.pdf.parser.FilteredTextRenderListener;
import java.io.File;
import java.io.OutputStreamWriter;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.BufferedWriter;
import java.io.IOException;
import java.util.Formatter;
import java.lang.StringBuilder;
public class ReadPdf {
private static String INPUTFILE = "F:/Users/jmack/Webwork/Redglue_PDF/live/ADP/APR/ADP_41.pdf";
public static void writeTextFile(String fileName, String s) {
// s = s.replaceAll("\u0063\u006B", "just a test");
s = s.replaceAll("\uFB00", "ff");
s = s.replaceAll("\uFB01", "fi");
s = s.replaceAll("\uFB02", "fl");
s = s.replaceAll("\uFB03", "ffi");
s = s.replaceAll("\uFB04", "ffl");
s = s.replaceAll("\uFB05", "ft");
s = s.replaceAll("\uFB06", "st");
s = s.replaceAll("\u0132", "IJ");
s = s.replaceAll("\u0133", "ij");
FileWriter output = null;
try {
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(fileName), "UTF-8"));
writer.write(s);
writer.close();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (output != null) {
try {
output.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
public static void main(String[] args) {
try {
PdfReader reader = new PdfReader(INPUTFILE);
int n = reader.getNumberOfPages();
String str = PdfTextExtractor.getTextFromPage(reader, 1, new SimpleTextExtractionStrategy());
writeTextFile("F:/Users/jmack/Webwork/Redglue_PDF/live/itext/read_test.txt", str);
}
catch (Exception e) {
System.out.println(e);
}
}
}
In the PDF referenced above one line reads:
part of its design difference is a roofline
But when I run the Java class above the text output contains:
part of its design diference is a roofine
Notice that difference became diference and roofline became roofine.
It is interesting to note that when I copy and paste from the PDF to stackoverflow's textfield, it also looks like the second sentence with the two ligatures "ff" and "fl" reduced to simply "f"s.
I am hoping that someone here can help me figure out how to catch the ligatures and perhaps replaces them with the characters they represent, as in the ligature "fl" being replaced with an actual "f" and a "l".
I ran some tests on the output from the PDFTextExtractor and attempted to replace the ligature unicode characters with the actual characters, but discovered that the unicode characters for those ligatures do not exist in the value it returns.
It seems that it must be something in iText itself that is not reading those ligatures correctly. I am hopeful that someone knows how to work around that.
Thank you for any help you can give!
TLDR: Converting PDF to text with iText, had missing characters, discovered they were ligatures, now I need to capture those ligatures, not sure how to go about doing that.
I have problem while writing to the file. I want to write contents of my input file to output file but while writing to the file, I am getting NULL value written at the end of file.
What's the reason behind that?
My code is:
import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
public class FileReading {
/**
* #param args
* #throws IOException
*/
public static void main(String[] args) throws IOException {
// TODO Auto-generated method stub
FileInputStream fi=new
FileInputStream("E:\\Tejas\\NewData_FromNov\\New_Folder\\bb.txt");
DataInputStream di=new DataInputStream(fi);
BufferedReader buf=new BufferedReader(new InputStreamReader(di));
FileOutputStream fout=new FileOutputStream("E:\\Tejas\\NewData_FromNov\\New_Folder\\Out_bb.txt");
int ss;
byte[] input=new byte[500];
int len=input.length;
while((ss=di.read(input,0,len))!=-1)
{
System.out.println(ss);
//fout.write(ss);
fout.write(input,0,len);
}
fout.close();
}
}
You're always writing out the full buffer, even if you've only read part of it because the third argument to write is len (the length of the buffer) instead of ss (the number of bytes read). Your loop should look like this:
int bytesRead; // Easier to understand than "ss"
byte[] buffer = new byte[500];
while((bytesRead = di.read(buffer, 0, buffer.length)) != -1)
{
System.out.println(bytesRead);
fout.write(buffer, 0, bytesRead);
}
Additionally:
You should close both the input and output streams in finally blocks to ensure they're always closed (even if there's an exception).
You don't need a DataInputStream - just a FileInputStream is fine here.
You're not using your BufferedReader at all.
Consider using Guava or a similar third-party library which contains utility methods to do all of this.
The read method returns the number of actually read bytes, or -1 if the end of the stream has been reached. So you should only write ss bytes, and not len bytes:
while ((ss = di.read(input, 0, len)) != -1) {
System.out.println(ss);
fout.write(input, 0, ss);
}
Note thet the DataInputStream and the BufferedReader are completely unnecessary here.