问题
Condition is if directory exists it has to create files in that specific directory with out creating a new directory.
The below code only creating a file with new directory but not for existing directory . For example the directory name would be like "GETDIRECTION"
String PATH = "/remote/dir/server/";
String fileName = PATH.append(id).concat(getTimeStamp()).append(".txt");
String directoryName = PATH.append(this.getClassName());
File file = new File(String.valueOf(fileName));
File directory = new File(String.valueOf(directoryName));
if(!directory.exists()){
directory.mkdir();
if(!file.exists() && !checkEnoughDiskSpace()){
file.getParentFile().mkdir();
file.createNewFile();
}
}
FileWriter fw = new FileWriter(file.getAbsoluteFile());
BufferedWriter bw = new BufferedWriter(fw);
bw.write(value);
bw.close();
回答1:
This code checks for the existence of the directory first and creates it if not, and creates the file afterwards. Please note that I couldn't verify some of your method calls as I don't have your complete code, so I'm assuming the calls to things like getTimeStamp() and getClassName() will work. You should also do something with the possible IOException that can be thrown when using any of the java.io.* classes - either your function that writes the files should throw this exception (and it be handled elsewhere), or you should do it in the method directly. Also, I assumed that id is of type String - I don't know as your code doesn't explicitly define it. If it is something else like an int, you should probably cast it to a String before using it in the fileName as I have done here.
Also, I replaced your append calls with concat or + as I saw appropriate.
public void writeFile(String value){
String PATH = "/remote/dir/server/";
String directoryName = PATH.concat(this.getClassName());
String fileName = id + getTimeStamp() + ".txt";
File directory = new File(directoryName);
if (! directory.exists()){
directory.mkdir();
// If you require it to make the entire directory path including parents,
// use directory.mkdirs(); here instead.
}
File file = new File(directoryName + "/" + fileName);
try{
FileWriter fw = new FileWriter(file.getAbsoluteFile());
BufferedWriter bw = new BufferedWriter(fw);
bw.write(value);
bw.close();
}
catch (IOException e){
e.printStackTrace();
System.exit(-1);
}
}
You should probably not use bare path names like this if you want to run the code on Microsoft Windows - I'm not sure what it will do with the / in the filenames. For full portability, you should probably use something like File.separator to construct your paths.
Edit: According to a comment by JosefScript below, it's not necessary to test for directory existence. The directory.mkdir() call will return true if it created a directory, and false if it didn't, including the case when the directory already existed.
回答2:
Trying to make this as short and simple as possible. Creates directory if it doesn't exist, and then returns the desired file:
/** Creates parent directories if necessary. Then returns file */
private static File fileWithDirectoryAssurance(String directory, String filename) {
File dir = new File(directory);
if (!dir.exists()) dir.mkdirs();
return new File(directory + "/" + filename);
}
回答3:
I would suggest the following for Java8+.
/**
* Creates a File if the file does not exist, or returns a
* reference to the File if it already exists.
*/
private File createOrRetrieve(final String target) throws IOException{
final Path path = Paths.get(target);
if(Files.notExists(path)){
LOG.info("Target file \"" + target + "\" will be created.");
return Files.createFile(Files.createDirectories(path)).toFile();
}
LOG.info("Target file \"" + target + "\" will be retrieved.");
return path.toFile();
}
/**
* Deletes the target if it exists then creates a new empty file.
*/
private File createOrReplaceFileAndDirectories(final String target) throws IOException{
final Path path = Paths.get(target);
// Create only if it does not exist already
Files.walk(path)
.filter(p -> Files.exists(p))
.sorted(Comparator.reverseOrder())
.peek(p -> LOG.info("Deleted existing file or directory \"" + p + "\"."))
.forEach(p -> {
try{
Files.createFile(Files.createDirectories(p));
}
catch(IOException e){
throw new IllegalStateException(e);
}
});
LOG.info("Target file \"" + target + "\" will be created.");
return Files.createFile(
Files.createDirectories(path)
).toFile();
}
回答4:
code:
// Create Directory if not exist then Copy a file.
public static void copyFile_Directory(String origin, String destDir, String destination) throws IOException {
Path FROM = Paths.get(origin);
Path TO = Paths.get(destination);
File directory = new File(String.valueOf(destDir));
if (!directory.exists()) {
directory.mkdir();
}
//overwrite the destination file if it exists, and copy
// the file attributes, including the rwx permissions
CopyOption[] options = new CopyOption[]{
StandardCopyOption.REPLACE_EXISTING,
StandardCopyOption.COPY_ATTRIBUTES
};
Files.copy(FROM, TO, options);
}
回答5:
Using java.nio.Path it would be quite simple -
public static Path createFileWithDir(String directory, String filename) {
File dir = new File(directory);
if (!dir.exists()) dir.mkdirs();
return Paths.get(directory + File.separatorChar + filename);
}
回答6:
If you create a web based application, the better solution is to check the directory exists or not then create the file if not exist. If exists, recreate again.
private File createFile(String path, String fileName) throws IOException {
ClassLoader classLoader = getClass().getClassLoader();
File file = new File(classLoader.getResource(".").getFile() + path + fileName);
// Lets create the directory
try {
file.getParentFile().mkdir();
} catch (Exception err){
System.out.println("ERROR (Directory Create)" + err.getMessage());
}
// Lets create the file if we have credential
try {
file.createNewFile();
} catch (Exception err){
System.out.println("ERROR (File Create)" + err.getMessage());
}
return file;
}
回答7:
java 8+ version
Files.createDirectories(Paths.get("/Your/Path/Here"));
The Files.createDirectories
creates a new directory and parent directories that do not exist.
The method does not thrown an exception if the directory already exist.
来源：https://stackoverflow.com/questions/28947250/create-a-directory-if-it-does-not-exist-and-then-create-the-files-in-that-direct