I am coming to an issue where I am trying to check if output folder is there and if not create one in my code below. So, I tried doing that way as shown in my code but I dont know if its the proper a way of doing it? can you please advise. thanks for the help.
here is my code:
String outputFolder2 = Printer.getOutputFolder();
File outFileTwo = new File(outputFolder2);
if (!outFileTwo.exists()) {
if (!outFileTwo.mkdir()) {
System.out.println("Failed to make directory for: " + outputFolder2);
}
}
To check if the directory exists:
Files.isDirectory(Paths.get("/the/path"))
To create dir if not exists:
Files.createDirectories(Paths.get("/the/path"))
Simply use
dirPathFileObj.mkdir();
From java.io.File;
If the method detects that no such directory exists, it will automatically create one. Otherwise, it will simply do nothing in terms of File creation.
It's recommended to use the nio package for new code that interacts with files -- it's faster, and easier to code for. Here's how I would write that code, in the form of a junit test that I ran to verify it:
#Test
public void testSomething() {
Path dirPath = Paths.get("C:/I/do/not/exist");
Path filePath = dirPath.resolve("newFile.txt");
try {
assertFalse(Files.exists(dirPath));
dirPath = createDirectories(dirPath);
filePath = Files.createFile(filePath);
assertTrue(Files.exists(filePath));
} catch (IOException iox) {
iox.printStackTrace();
} finally {
try {
Files.deleteIfExists(filePath);
Files.deleteIfExists(dirPath);
} catch (Exception e) {
e.printStackTrace();
}
}
}
This will create C:\I\do\not\exist\newFile.txt, then delete C:\I\do\not\exist, (leaving C:\I\do\not\). For production code, you'd want to remove the asserts and fill in those catch clauses
Related
I'm creating every time a file moving and replacing it from source folder to a destination folder with the same name
in a loop and this is the problem :
For the first move and replace, it works well then it yells the process cannot access the file because it is being used by another process. when replacing the file in the destination folder
and this is the method moving the file and replacing it every time
public static void moveAndReplaceFile(String source, String destination) {
try {
Files.move(
Paths.get(source),
Paths.get(destination),
StandardCopyOption.REPLACE_EXISTING);
} catch (IOException e) {
LOGGER.error("Fail when moving and replacing");
}
}
can you help me guys? thanks in advance
If its a network storage that you are using, then this can happen. As a workaround, you can try adding a sleep of 60seconds before executing the Files.Move API.
I suggest you to add the ATOMIC_MOVE option if supported :
public static void moveAndReplaceFile(String source, String destination) {
try {
Files.move(
Paths.get(source),
Paths.get(destination),
StandardCopyOption.REPLACE_EXISTING,
StandardCopyOption.ATOMIC_MOVE);
} catch (IOException e) {
LOGGER.error("Fail when moving and replacing");
}
}
See : https://docs.oracle.com/javase/tutorial/essential/io/move.html
using java 8, tomcat 8
Hi, i am loading a file using properties, but i have a check before loading which returns the same properties object if its already been loaded (not null). which is a normal case scenario but i want to know if there is any way that if any change occur in target file, and some trigger should be called and refreshes all the properties objects. here is my code.
public static String loadConnectionFile(String keyname) {
String message = "";
getMessageFromConnectionFile();
if (propertiesForConnection.containsKey(keyname))
message = propertiesForConnection.getProperty(keyname);
return message;
}
public static synchronized void getMessageFromConnectionFile() {
if (propertiesForConnection == null) {
FileInputStream fileInput = null;
try {
File file = new File(Constants.GET_CONNECTION_FILE_PATH);
fileInput = new FileInputStream(file);
Reader reader = new InputStreamReader(fileInput, "UTF-8");
propertiesForConnection = new Properties();
propertiesForConnection.load(reader);
} catch (Exception e) {
Utilities.printErrorLog(Utilities.convertStackTraceToString(e), logger);
} finally {
try {
fileInput.close();
} catch (Exception e) {
Utilities.printErrorLog(Utilities.convertStackTraceToString(e), logger);
}
}
}
}
the loadConnectionFile method executes first and calls getMessageFromConnectionFile which has check implemented for "null", now if we remove that check it will definitely load updated file every time but it will slower the performance. i want an alternate way.
hope i explained my question.
thanks in advance.
Java has a file watcher service. It is an API. You can "listen" for changes in files and directories. So you can listen for changes to your properties file, or the directory in which your properties file is located. The Java Tutorials on Oracle's OTN Web site has a section on the watcher service.
Good Luck,
Avi.
I'm trying to copy a resource in my project onto another location on the disk. So far, I have this code:
if (!file.exists()){
try {
file.createNewFile();
Files.copy(new InputSupplier<InputStream>() {
public InputStream getInput() throws IOException {
return Main.class.getResourceAsStream("/" + name);
}
}, file);
} catch (IOException e) {
file = null;
return null;
}
}
And it works fine, but the InputSupplier class is deprecated, so I was wondering if there was a better way to do what I'm trying to do.
See the documentation for the Guava InputSupplier class:
For InputSupplier<? extends InputStream>, use ByteSource instead. For InputSupplier<? extends Reader>, use CharSource. Implementations of InputSupplier that don't fall into one of those categories do not benefit from any of the methods in common.io and should use a different interface. This interface is scheduled for removal in December 2015.
So in your case, you're looking for ByteSource:
Resources.asByteSource(url).copyTo(Files.asByteSink(file));
See this section of the Guava Wiki for more information.
If you're looking for a pure Java (no external libraries) version, you can do the following:
try (InputStream is = this.getClass().getClassLoader().getResourceAsStream("/" + name)) {
Files.copy(is, Paths.get("C:\\some\\file.txt"));
} catch (IOException e) {
// An error occurred copying the resource
}
Note that this is only valid for Java 7 and higher.
We have a legacy system that has a admim module that allows users to upload jar files. After the upload, the jar file is validated and if not compliant to internal rules, it is deleted.
The problem is that windows is throwing an exception telling that the file "is already being used by another process." (when I call Files.delete(tmpJar);). I'm not able to identify why the file is open. Seems to me that I have closed everything.
First, we are using primefaces (4.0) to upload the file. Primefaces relies on commons-fileupload (1.3.1). It call the following method:
public void handleFileUpload(FileUploadEvent event) {
Path tmpJar = null;
try {
tmpJar = Files.createFile(Paths.get(event.getFile().getFileName()));
Files.write(tmpJar, event.getFile().getContents());
} catch (IOException e) {
LOGGER.error(e.getMessage(), e);
}
if (tmpJar != null) {
try {
this.validateJar(tmpJar.toString());
Files.delete(tmpJar);
} catch (IOException e) {
LOGGER.error(e.getMessage(), e);
}
}
}
Before NIO Files.write, I was using "standard" java IO classes. The problem isn't related to the above code, because if I comment the call to validateJar, Files.delete(tmpJar) is executed without problems and the file is removed. So, the problem is related with the code below, but I can't find where...
Job is an internal class, basically a simple POJO. "jobAnnotation" is a custom annotation to identify Jobs. I have shortened the code, but the essencial parts are preserved.
private List<Job> validateJar(final String jarPath) throws IOException {
List<Job> jobs = new ArrayList<Job>();
try (JarFile jarFile = new JarFile(jarPath)) {
URL[] jars = { new URL("file:" + jarPath) };
ClassLoader jobClassLoader = URLClassLoader.newInstance(jars, this.getClass().getClassLoader());
Enumeration<JarEntry> jarEntries = jarFile.entries();
while (jarEntries.hasMoreElements()) {
JarEntry jarEntry = jarEntries.nextElement();
String className = jarEntry.getName();
Class<?> classToLoad;
try {
classToLoad = Class.forName(className, true, jobClassLoader);
} catch (Exception e1) {
LOGGER.error(e1.getMessage(), e1);
continue;
}
if (classToLoad.isAnnotationPresent(jobAnnotation)) {
String vlr = null;
try {
Class<?> jobClass = (Class<?>) Class.forName(classToLoad.getCanonicalName(), true, jobClassLoader);
Annotation annotation = jobClass.getAnnotation(jobAnnotation);
Method method = annotation.getClass().getMethod("getValue");
vlr = ((String) method.invoke(annotation, new Object[0]));
} catch (Exception e1) {
LOGGER.error(e1.getMessage(), e1);
}
Job job = new Job();
job.setEnabled(true);
job.setJarfile(jarPath);
job.setClassName(classToLoad.getName());
Parameter parameter = new Parameter();
parameter.setRequired(true);
parameter.setName("name");
parameter.setValue(vlr);
job.addParameter(parameter);
jobs.add(job);
}
}
} catch (IOException e) {
throw e;
}
return jobs;
}
Before using try-with-resources, I was using regular try-catch-finally to close the JarFile, thats the only thing that has a explicit close method. Probably is the classloading that is holding the file open, but I don't know how to close it.
I did some searches, and I found that I can't unload classes (Unloading classes in java?).
So, the problem is, how do I release it? Or how can I remove the file?
BTW, I'm using java 1.7.0_71, jboss 7.1.1, windows 7 (64).
The URLClassLoader class already has a close() method. The close() method will close any Jar file that are opened with the URLClassLoader. This should prevent the "file already in use" exception.
File is already being used by another process. says that it could be not your fault, maybe just another application is used that file. You can check this question to find a process which is used your file.
Some Virus scanner software take a long time in checking JARs. Try to disable the Virusscanner. Other candidates can be the Windows indexer process, or the explorer.exe itself. When you don't find any reason for the file lock, try a delay between the validation and the deletion. Maybe you need a loop with multiple tries.
I am having a problem writing to a .xml file inside of my jar. When I use the following code inside of my Netbeans IDE, no error occurs and it writes to the file just fine.
public void saveSettings(){
Properties prop = new Properties();
FileOutputStream out;
try {
File file = new File(Duct.class.getResource("/Settings.xml").toURI());
out = new FileOutputStream(file);
prop.setProperty("LAST_FILE", getLastFile());
try {
prop.storeToXML(out,null);
} catch (Exception e) {
JOptionPane.showMessageDialog(null, e.toString());
}
try {
out.close();
} catch (Exception e) {
JOptionPane.showMessageDialog(null, e.toString());
}
} catch (Exception e) {
JOptionPane.showMessageDialog(null, e.toString());
}
}
However, when I execute the jar I get an error saying:
IllegalArguementException: uri is not hierachal
Does anyone have an idea of why it's working when i run it in Netbeans, but not working when i execute the jar. Also does anyone have a solution to the problem?
The default class loader expects the classpath to be static (so it can cache heavily), so this approach will not work.
You can put Settings.xml in the file system if you can get a suitable location to put it. This is most likely vendor and platform specific, but can be done.
Add the location of the Settings.xml to the classpath.
I was also struggling with this exception. But finally found out the solution.
When you use .toURI() it returns some thing like
D:/folderName/folderName/Settings.xml
and hence you get the exception "URI is not hierarchical"
To avoid this call the method getPath() on the URI returned, which returns something like
/D:/folderName/folderName/Settings.xml
which is now hierarchical.
In your case, the 5th line in your code should be
File file = new File(Duct.class.getResource("/Settings.xml").toURI().getPath());