I am working with a coverity issue which i need to validate a file name
using regEx in java . In my application support .pdf , .txt , csv etc . My
file name getting as xxx.txt from user . i want to validate my file name
with proper extension format and not included any special character other
than dot ( eg .txt) .
filePath = properties.getProperty("DOCUMENT.LIBRARY.LOCATION");
String fileName = (String) request.getParameter("read");
Only If the file path is completed itsproper validation, the below code should be work .
filePath += "/" + fileName;
This is a terrible answer as it only verifies the filename ends with the desired extension, but doesn't verify the rest of the filename as requested in the original question. Something more like this would be MUCH better:
fileName.matches("[-_. A-Za-z0-9]+\\.(pdf|txt|csv)");
This ensures the filename contains only ONE OR MORE -, _, PERIOD, SPACE, or alphanumeric characters, followed by exactly one of .pdf, .txt or .csv at the end of the filename. Your system might allow other characters in filenames and you could add them to this list if desired. An alternate, less secure approach is to prevent 'bad' characters something like:
fileName.matches("[^/\]+\\.(pdf|txt|csv)");
Which simply prevents / or \ characters from being in the file name before the required ending extension. But this doesn't prevent potentially other dangerous characters, like NULL bytes, for example.
Have a look at String.endsWith() method
if (fileName.endsWith(".pdf")) {
// do something
}
Or use the method String.matches()
fileName.matches("\\.(pdf|txt|csv)$")
Related
I have a program where I save school grades in a .txt File.
I want to let the user choose where this File should be saved.
It works with the JFileChooser find but Java have a problem with the
FilePath.
The filepath from the JFileChooser looks like this:
C:\Users...\Documents\n.txt
But if I want to read the TextFile in the Program Java says that
it couldn't find the Filepath.
It should look like this:
C:\Users\...\Documents\n.txt
How can I get the Path with double-backslashes?
public void actionPerformed(ActionEvent e) {
JFileChooser jf = new JFileChooser();
jf.showSaveDialog(null);
String fPath = jf.getSelectedFile().getPath();
fPath.replaceAll('\', '\\');
System.out.println(p);
}
that does not work it says invalid character constant
There are some places where the backslash serves as escape character, and must be escaped, to be simply the backslash of a Windows path separator.
These places are inside .properties files, java String literals and some more.
You could for Windows paths alternatively use a slash (POSIX compliance of Windows).
fPath = fPath.replace('\\', '/');
Backslash:
fPath = fPath.replace("\\", "\\\\");
The explanation is that a single backslash inside char and string literals must be escaped: two backslashes represent a single backslash.
With regular expressions (replaceAll) a backlash is used as command: a digit is expressed as \d and as java String: "\\d". Hence the backslash itself becomes (behold):
fPath = fPath.replaceAll("\\\\", "\\\\\\\\"); // PLEASE NOT
I almost did not see it, but methods on String do not alter it, but return a new value, so one needs to assign the result.
When using hard coded file names in Java you should always use forward slashes / as file separators. Java knows how to handle them on Windows.
Also you should not use absolute paths. You don't know if that paths will exist at the target system. You should use either relative paths starting with your classpath as root "/..." or get some system dependen places from System.getProperty() https://docs.oracle.com/javase/8/docs/api/java/lang/System.html#getProperties--
Multiple issues in your code:
public void actionPerformed(ActionEvent e) {
JFileChooser jf = new JFileChooser();
jf.showSaveDialog(null);
String fPath = jf.getSelectedFile().getPath();
// fPath is a proper file path. This can be used directly with
// new File(fPath). The contents will contain single \ character
// as Path separator
fPath.replaceAll('\', '\\');
// I guess you are trying to replace a single \ character with \\
// character. You need to escape the \ character. You need to
// consider that both parameters are regexes.
// doing it is:
// fPath.replaceAll("\\\\", "\\\\\\\\");
// And then you need to capture the return value. Strings are
// immutable in java. So it is:
// fPath = fPath.replaceAll("\\\\", "\\\\\\\\");
System.out.println(p);
// I don't know what p is. I guess you want to use fPath
}
That said, I do not understand why you want to convert the path returned by JFileChooser.
You don't need the file path with double backslashes in Java. Double backslashes are for:
The Java compiler, inside string literals.
The Java regex compiler.
Everywhere else you can obtain backslashes, or use forward slashes.
Possibly you are looking for java.util.Properties?
I'm developing a project for college which consist reading a CSV file and converting that to a PDF file. That part is fine, I have already done that.
In the end I need to show the name of the PDF file without the full path of where it was created. In other words, I just want the to show the name.
I search a lot to see if there is a simple method that show the name like Java has to show only the name of the File like
file.getName();
Whenever you use iText to create a PDF file, your code sets the target which usually is an OutputStream. If you use a FileOutputStream there, you know the file it writes to.
Thus, all you have to do to to show the name of the PDF File is to inspect your own code and check which target it sets.
Use getBaseName in Apache Commons IO.
getBaseName
public static String getBaseName(String filename)
Gets the base name, minus the full path and extension, from a full
filename.
This method will handle a file in either Unix or Windows format. The
text after the last forward or backslash and before the last dot is
returned.
a/b/c.txt --> c
a.txt --> a
a/b/c --> c
a/b/c/ --> ""
The output will be the same irrespective of the machine that the code
is running on.
Parameters:
filename - the filename to query, null returns null
Returns:
the name of the file without the path, or an empty string if none exists. Null bytes inside string will be removed
Source: https://commons.apache.org/proper/commons-io/javadocs/api-2.5/org/apache/commons/io/FilenameUtils.html#getBaseName(java.lang.String)
If you also need the extension, use getExtension. Which would probably always be .pdf, but you know, it's perfectly valid to have a PDF file without the .pdf filename extension. No sane person would do that but it is better to be prepared for insane users.
I'm reading in an absolute pathname from an ini file and storing the pathname as a String value in my program. However, when I do this, the value that gets stored somehow seems to be losing the backslash so that the path just comes out one big jumbled mess? For example, the ini file would have key, value of:
key=C:\folder\folder2\filename.extension
and the value that gets stored is coming out as C:folderfolder2filename.extension.
Would anyone know how to escape the keys before it gets read in?
Let's also assume that changing the values of the ini file is not an alternative because it's not a file that I create.
Try setting the escape property to false in Ini4j.
http://ini4j.sourceforge.net/apidocs/org/ini4j/Config.html#setEscape%28boolean%29
You can try:
Config.getGlobal().setEscape(false);
If you read the file and then translate the \ to a / before processing, that would work. So the library you are using has a method Ini#load(InputStream) that takes the INI file contents, call it like this:
byte[] data = Files.readAllBytes(Paths.get("directory", "file.ini");
String contents = new String(data).replaceAll("\\\\", "/");
InputStream stream = new ByteArrayInputStream(contents.getBytes());
ini.load(stream);
The processor must be doing the interpretation of the back-slashes, so this will give it data with forward-slashes instead. Or, you could escape the back-slashes before processing, like this:
String contents = new String(data).replaceAll("\\\\", "\\\\\\\\");
I'm trying to build a Java regex to search a .txt file for a Windows formatted file path, however, due to the file path containing literal backslashes, my regex is failing.
The .txt file contains the line:
C\Windows\SysWOW64\ntdll.dll
However, some of the filenames in the text file are formatted like this:
C\Windows\SysWOW64\ntdll.dll (some developer stuff here...)
So I'm unable to use String.equals
To match this line, I'm using the regex:
filename = "C\\Windows\\SysWOW64\\ntdll.dll"
read = BufferedReader.readLine();
if (Pattern.compile(Pattern.quote(filename), Pattern.CASE_INSENSITIVE).matcher(read).find()) {
I've tried escaping the literal backslashes, using the replace method, i.e:
filename.replace("\\", "\\\\");
However, this is failing to find, I'm guessing this is because I need to further escape the backslashes after the Pattern has been built, I'm thinking I might need to escape upto an additional four backslashes, i.e:
Pattern.replaceAll("\\\\", "\\\\\\\\");
However, each time I try, the pattern doesn't get matched. I'm certain it's a problem with the backslashes, but I'm not sure where to do the replacement, or if there's a better way of building the pattern.
I think the problem is further being compounded as the replaceAll method also uses a regex, with means the pattern will have it's own backslashes in there, to deal with the case insensitivity.
Any input or advice would be appreciated.
Thanks
Seems like you're attempting to to a direct comparison of String against another. For exact matches, you could do (
if (read.equalsIgnoreCase(filename)) {
of simply
if (read.startsWith(filename)) {
Try this :
While reading each line from the file, replace '\' by '\\'.
Then :
String lLine = "C\\Windows\\SysWOW64\\ntdll.dll";
Pattern lPattern = Pattern.compile("C\\\\Windows\\\\SysWOW64\\\\ntdll\\.dll");
Matcher lMatcher = lPattern.matcher(lLine);
if(lMatcher.find()) {
System.out.println(lMatcher.group());
}
lLine = "C\\Windows\\SysWOW64\\ntdll.dll (some developer stuff here...)";
lMatcher = lPattern.matcher(lLine);
if(lMatcher.find()) {
System.out.println(lMatcher.group());
}
The correct usage will be:
String filename = "C\\Windows\\SysWOW64\\ntdll.dll";
String file = filename.replace('\\', ' ');
I try to create file in storage and for file name I use webview.getTitle() string.
When I save file with name for example "Google.jpg" or "Foreca.jpg" it works well, but...
not all webpage titles is so clear.
For example:
"android - java.io.ioexception: open failed: einval (Invalid argument)
when saving a image to external storage - Stack Overflow:"
There is a lot of wrong characters, if I need this title put in file name.
Is there easy way to replace all this :;?!/<>- characters to ""?
Yes, you can use replaceAll():
String fileName = webview.getTitle();
filename = fileName.replaceAll("(\\p{Punct})","") // fixed \p
Check out the Java documentation for more.