I am trying to read the content of a jar in a folder accessible from the root directory of my project, the jar is correctly found, however, my code only prints the name of the META-INF file, here's what i tried so far:
public static void provideClassList(String jarName) {
List<String> classNames = new ArrayList<String>();
ZipInputStream zip;
try {
zip = new ZipInputStream(new FileInputStream(StaticValues.JARS_PATH.concat(jarName)));
for (ZipEntry entry = zip.getNextEntry(); entry != null; entry = zip.getNextEntry()) {
System.out.println(entry);//PRINTS META-INF/
if (!entry.isDirectory() && entry.getName().endsWith(".class")) {
String className = entry.getName().replace('/', '.');
classNames.add(className.substring(0, className.length() - ".class".length()));
}
zip.close();
}
// explore content (THIS IS ACTUALLY EMPTY)
for (String className : classNames) {
try {
Class<?> clazz = Class.forName(className);
System.out.println(clazz.getCanonicalName());
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
} catch (FileNotFoundException e1) {
e1.printStackTrace();
} catch (IOException ex) {
}
}
I cant see any permissioning issue, also, i have opened the jar file manually from console and the content that i expect to find is all there.
Those are the properties i see from eclipse:
You are calling zip.close(); inside of the for loop, that is propably the reason you only get the first entry in the jar. Move it outside of the for loop, or even better, use a try-with-resources Statement.
try (FileInputStream fis = new FileInputStream(StaticValues.JARS_PATH.concat(jarName);
ZipInputStream zip = new ZipInputStream(fis)) {
// code for iterating goes here
}
Related
This is the code
public static void readCharacters() {
try (FileInputStream fi = new FileInputStream("main/characters.dat"); ObjectInputStream os = new ObjectInputStream(fi)) {
characterList = (LinkedList<Character>) os.readObject();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
This is the structure:
And this is the Error
java.io.FileNotFoundException: main\characters.dat (The system cannot find the path specified)
What I want is to include the characters.dat file in my jar, and be able to read and write it while the program runs. Is there a different way to write the path? or to put the .dat file in a different position.
Also the writing method:
public static void writeCharacters() {
try (FileOutputStream fs = new FileOutputStream("main/characters.dat"); ObjectOutputStream os = new ObjectOutputStream(fs)) {
System.out.println("Writing Characters...");
os.writeObject(characterList);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
You can't. You can do one or the other. JAR files are not file systems, and their entries are not files. You can read it with an input stream:
InputStream in = this.getClass().getResourceAsStream("/main/characters.dat");
Check it for null before proceeding.
The jar is for read-only resources. You can use it for the initial file, as a kind of template.
Path path = Paths.get(System.getProperty("user.home") + "/myapp/chars.dat");
Files.mkdirs(path.getParentPath());
if (!Files.exists()) {
try (InputStream in =
Controller.class.getResourceAsStream("/main/characters.dat")) {
Files.copy(in, path);
}
}
The above copies the initial.dat resource from the jar to the user's home "myapp" directory, which is a common solution.
System.getProperty("user.dir") would the running directory. One can also take the jar's path:
URL url = Controller.class.getResource("/main/characters.dat");
String s = url.toExternalForm(); // "jar:file:/.... /xxx.jar!/main/characters.dat"
From that you can also construct the jar's directory. Mind to check Windows, Linux, spaces and such.
URL url = Controller.class.getProtectionDomain().getCodeSource().getLocation();
The solution above risks a NullPointerException, and works a bit differenly running inside the IDE or stand-alone.
Important note:
When using getResourceAsStream, you must start your path by slash /, this specifies the root of your jar, .getResourceAsStream("/file.txt");
In my case my file was a function argument, String filename, I had to do it like this:
InputStream in = this.getClass().getResourceAsStream("/" + filename);
Here is my class, what I am doing wrong. Why is my text document becoming a file folder. Please explain what is going on and how I can correct it. Thank you
public class InputOutput {
public static void main(String[] args) {
File file = new File("C:/Users/CrypticDev/Desktop/File/Text.txt");
Scanner input = null;
if (file.exists()) {
try {
PrintWriter pw = new PrintWriter(file);
pw.println("Some data that we have stored");
pw.println("Another data that we stored");
pw.close();
} catch(FileNotFoundException e) {
System.out.println("Error " + e.toString());
}
} else {
file.mkdirs();
}
try {
input = new Scanner(file);
while(input.hasNext()) {
System.out.println(input.nextLine());
}
} catch(FileNotFoundException e) {
System.out.println("Error " + e.toString());
} finally {
if (input != null) {
input.close();
}
}
System.out.println(file.exists());
System.out.println(file.length());
System.out.println(file.canRead());
System.out.println(file.canWrite());
System.out.println(file.isFile());
System.out.println(file.isDirectory());
}
}
Thanks. The above is my Java class.
You mistakingly assume Text.txt is not a directory name.
mkdirs() creates a directory (and all directories needed to create it). In your case 'Text.txt'
See here: https://docs.oracle.com/javase/7/docs/api/java/io/File.html#mkdirs().
It is perfectly fine for a directory to have a . in it.
You could use getParentFile() to get the directory you want to create and use mkdirs() on that.
For additional informations. Here is the différence between the two representaions of files and directories:
final File file1 = new File("H:/Test/Text.txt"); // Creates NO File/Directory
file1.mkdirs(); // Creates directory named "Text.txt" and its parent directory "H:/Test" if it doesn't exist (may fail regarding to permissions on folders).
final File file = new File("H:/Test2/Text.txt"); // Creates NO File/Directory
try {
file.createNewFile(); // Creates file named "Text.txt" (if doesn't exist) in the folder "H:/Test2". If parents don't exist, no file is created.
} catch (IOException e) {
e.printStackTrace();
}
Replace your code:
else {
file.mkdirs();
}
with:
else {
if (!file.isFile()&&file.getParentFile().mkdirs()) {
try {
file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
}
Try to create file in specific directory but it shows the error FileNotFound. Why?
Am I using impossible path? I really don't know, but is seems like the code should be working.
String day=/1;
String zn="/zn";
File_name=zn
String root= Environment.getExternalStorageDirectory().toString();
File_path=root+day;
File file1 = new File(File_path,File_name);
file1.mkdirs();
if(!file1.exists()) {
try {
file1.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
try {
OutputStream fos= new FileOutputStream(file1);
String l,d,p;
l = lessnum.getText().toString();
d = desc.getText().toString();
p = place.getText().toString();
fos.write(l.getBytes());
fos.write(d.getBytes());
fos.write(p.getBytes());
fos.close();
Change your code as for creating a file on sdcard
String root= Environment.getExternalStorageDirectory().getAbsolutePath();
String File_name = "File_name.Any_file_Extension(like txt,png etc)";
File file1 = new File(root+ File.separator + File_name);
if(!file1.exists()) {
try {
file1.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
In current you you are also missing file Extension with file name so change String zn as zn="/zn.txt";
and make sure you have added Sd card permission in AndroidManifest.xml :
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
First you make a directory
String root= Environment.getExternalStorageDirectory().toString();
String dirName =
root+ "abc/123/xy";
File newFile = new File(dirName);
newFile.mkdirs();
then you create a file inside that directory
String testFile = "test.txt";
File file1 = new File(dirName,testFile);
if(!file1.exists()){
try {
file1.createNewFile();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
then do your file writing operations
try { OutputStream fos= new FileOutputStream(file1);
String l,d,p;
l = lessnum.getText().toString();
d = desc.getText().toString();
p = place.getText().toString();
os.write(l.getBytes());
fos.write(d.getBytes());
fos.write(p.getBytes());
fos.close();
}
catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
I think this will help you...
Thanks...
you will need to give your app the correct permission to write to the SD Card by adding the line below to your Manifest:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
And check http://developer.android.com/reference/android/os/Environment.html#getExternalStorageDirectory%28%29
String root= Environment.getExternalStorageDirectory().toString();
String dirName =
root+ "abc/123/xy";
File newFile = new File(dirName);
newFile.mkdirs();
String testFile = "test.txt";
File file1 = new File(dirName,testFile);
if(!file1.exists()){
try {
file1.createNewFile();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
And and <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
on manifest file...
Thanks...
Here is your latest attempt:
File_path = root + File.separator + day;
File f_dir = new File(File_path);
f_dir.mkdirs();
File file1 = new File(f_dir, File_name);
if (!file1.exists()) {
try {
file1.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
try {
OutputStream fos= new FileOutputStream(file1);
If you showed us the complete stacktrace and error message it would be easier to figure out what is going wrong, but I can think of a couple of possibilities:
You are not checking the value returned by f_dir.mkdirs(), and it could well be returning false to indicate that the directory path was not created. This could mean that:
The directory already existed.
Something existed but it wasn't a directory.
Some part of the directory path could not be created ... for one of a number of possible reasons.
The file1.exists() call will return true if anything exists with that pathname given by the object. The fact that something exists doesn't necessarily mean that you can open it for writing:
It could be a directory.
It could be a file that the application doesn't have write permissions for.
It could be a file on a read-only file system.
And a few other things.
If I was writing this, I'd write it something like this:
File dir = new File(new File(root), day);
if (!dir.exists()) {
if (!dir.mkdirs()) {
System.err.println("Cannot create directories");
return;
}
}
File file1 = new File(dir, fileName);
try (OutputStream fos= new FileOutputStream(file1)) {
...
} catch (FileNotFoundException ex) {
System.err.println("Cannot open file: " + ex.getMessage());
}
I only attempt to create the directory if required ... and check that the creation succeeded.
Then I simply attempt to open the file to write to it. If the file doesn't exist it will be created. If it cannot be created, then the FileNotFoundException message should explain why.
Notice that I've also corrected the style errors you made in your choice of variable names.
well my question is really simple, is about an unexpected behavior (or at least is unexpected to me) while I try to zip a directory, I have the following methods that I've created on my own (I'm quite aware that I'm not handling exceptions and all that stuff, It is because (by now) I'm just doing this to learn how to do it so stability "is not really important"), here is the code:
public static void zipDirectory(File srcDirectory, File zipFile) throws IllegalArgumentException {
if (!srcDirectory.isDirectory()) {
throw new IllegalArgumentException("The first parameter (srcDirectory) MUST be a directory.");
}
int bytesRead;
byte[] dataRead = new byte[1000];
BufferedInputStream in = null;
ZipOutputStream zOut;
try {
zOut = new ZipOutputStream(new BufferedOutputStream(new FileOutputStream(zipFile)));
for (File f : srcDirectory.listFiles()) {
if (f.isDirectory()) {
FileUtilities.zipInnerDirectory(f,zOut);
}else {
in = new BufferedInputStream(new FileInputStream(f.getAbsolutePath()), 1000);
zOut.putNextEntry(new ZipEntry(f.getPath()));
while((bytesRead = in.read(dataRead,0,1000)) != -1) {
zOut.write(dataRead, 0, bytesRead);
}
zOut.closeEntry();
}
}
zOut.flush();
zOut.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
private static void zipInnerDirectory(File dir, ZipOutputStream zOut) throws IllegalArgumentException {
if (!dir.isDirectory()) {
throw new IllegalArgumentException("The first parameter (srcDirectory) MUST be a directory.");
}
BufferedInputStream in = null;
int bytesRead;
byte[] dataRead = new byte[1000];
try {
for (File f : dir.listFiles()) {
if (f.isDirectory()) {
FileUtilities.zipInnerDirectory(f,zOut);
}else {
in = new BufferedInputStream(new FileInputStream(f.getAbsolutePath()), 1000);
zOut.putNextEntry(new ZipEntry(f.getPath()));
while((bytesRead = in.read(dataRead,0,1000)) != -1) {
zOut.write(dataRead, 0, bytesRead);
}
zOut.closeEntry();
}
}
zOut.flush();
zOut.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
As I said is not my best coding so please don't judge the code (or at least don't be too strict ;) ), I know it can be so much better; ok the "unexpected behavior" is this, let's say that I have the following directory:
H:\MyDir1\MyDir2\MyDirToZip
when i send as a parameter a file created with that path (new File("H:\\MyDir1\\MyDir2\\MyDirToZip")) everything's work pretty fine the zip is created successfully, the thing is that when I open (unzip) the files inside the zip they have the next structure:
H:\MyDir1\MyDir2\MyDirToZip
when I was expecting to find inside just:
\MyDirToZip
without H: \MyDir1 \MyDir2 which are "unnecessary" (BTW they just contain one to each other in the appropriate order, i mean, the other files that are in them are not compressed, that is why I say they are unnecessary) so the question is, what I'm I doing wrong? how can I specify that I just want to zip the structure down the srcDirectory?
zOut.putNextEntry(new ZipEntry(f.getPath()));
This should be the problem. f.getPath() will return a path that's relative to some root directory (probably your current working dir), but not relative to the directory you are zipping. You need to figure out a way to get the relative path from the zip directory, possibly this will do:
new ZipEntry(f.getAbsolutePath().substring(zipDir.getAbsolutePath().length()))
or, if you want the root directory added:
new ZipEntry(zipDir.getName() + "/"
+ f.getAbsolutePath().substring(zipDir.getAbsolutePath().length()))
I am making a game in JAVA where I want to come up with a list of files in a certain directory in my jar so I can make sure to have a list of those classes to be used in the game.
For example say in my jar I have a directory
mtd/entity/creep/
I want to get a list of all the .class files in that directory using java code from another class in the jar.
What is the best code to do so?
Old java1.4 code, but that would give you the idea:
private static List getClassesFromJARFile(String jar, String packageName) throws Error
{
final List classes = new ArrayList();
JarInputStream jarFile = null;
try
{
jarFile = new JarInputStream(new FileInputStream(jar));
JarEntry jarEntry;
do
{
try
{
jarEntry = jarFile.getNextJarEntry();
}
catch(IOException ioe)
{
throw new CCException.Error("Unable to get next jar entry from jar file '"+jar+"'", ioe);
}
if (jarEntry != null)
{
extractClassFromJar(jar, packageName, classes, jarEntry);
}
} while (jarEntry != null);
closeJarFile(jarFile);
}
catch(IOException ioe)
{
throw new CCException.Error("Unable to get Jar input stream from '"+jar+"'", ioe);
}
finally
{
closeJarFile(jarFile);
}
return classes;
}
private static void extractClassFromJar(final String jar, final String packageName, final List classes, JarEntry jarEntry) throws Error
{
String className = jarEntry.getName();
if (className.endsWith(".class"))
{
className = className.substring(0, className.length() - ".class".length());
if (className.startsWith(packageName))
{
try
{
classes.add(Class.forName(className.replace('/', '.')));
} catch (ClassNotFoundException cnfe)
{
throw new CCException.Error("unable to find class named " + className.replace('/', '.') + "' within jar '" + jar + "'", cnfe);
}
}
}
}
private static void closeJarFile(final JarInputStream jarFile)
{
if(jarFile != null)
{
try
{
jarFile.close();
}
catch(IOException ioe)
{
mockAction();
}
}
}
Probably the best approach is to list the classes at compile time.
There is a fragile runtime approach. Take you Class (MyClass.class of this.getClass()). Call getProtectionDomain. Call getCodeSource. Call getLocation. Call openConnection. (Alternatively open a resource.) Cast to JarURLConnection. Call getJarFile. Call entries. Iterate through checking getName. I really do not recommend this approach.
10 years after the question, I propose an another way to do the job:
private static void listFilesFromDirectoryInsideAJar(String pathToJar,String directory,String extension) {
try {
JarFile jarFile = new JarFile(pathToJar);
Enumeration<JarEntry> e = jarFile.entries();
while (e.hasMoreElements()) {
JarEntry candidat = e.nextElement();
if (candidat.getName().startsWith(directory) &&
candidat.getName().endsWith(extension))
LOG.info(candidat.getName());
}
} catch (IOException e) {
LOG.error(e.getMessage(),e);
}
}
Remember that JAR files are just ZIP files renamed, and it's very easy to read the contents of ZIP files in Java:
File jarName = null;
try
{
jarName = new File (Dir.class.getProtectionDomain().getCodeSource().getLocation().toURI());
}
catch (Exception e)
{
e.printStackTrace();
}
try
{
ZipFile zf=new ZipFile(jarName.getAbsoluteFile());
Enumeration e=zf.entries();
while (e.hasMoreElements())
{
ZipEntry ze=(ZipEntry)e.nextElement();
System.out.println(ze.getName());
}
zf.close();
} catch (IOException e)
{
e.printStackTrace();
}
It's not possible, as Java doesn't provide direct access to the jar file the classes are loaded from. You could try to parse the java.class.path system property to find it, but that wouldn't work under all circumstances. Or you could restrict on where the jar file has to reside, or provide the list of the classes in a different way (for example via the manifest file).