how to download a jar file using java urlconnection

[carmine crescent]

<@&987246554085740594> please have a look, thanks.

[grim lake]

First of, don't do unsafe casts

Huh

Where did the message go ?

[viscid light]

How can i download a jar file using java what i already tried is

 // final URL jarUrl = new URL("jar:https://repo.maven.apache.org/maven2/org/springframework/spring-web/6.1.12/spring-web-6.1.12.jar!/");

    private void download(URL jarUrl, String directory) throws IOException { 
        final String[] splittedUrl = (jarUrl.toString().split("/"));
        final String fileName = splittedUrl[splittedUrl.length - 1];
        final File file = new File(directory + fileName);
        final JarURLConnection jarUrlConnection = (JarURLConnection) jarUrl.openConnection();

        
        final InputStream inputStream = jarUrlConnection.getInputStream();
        final InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
        try (final FileOutputStream fileOutputStream = new FileOutputStream(file)) {
            int readByte = inputStreamReader.read();
            while (readByte != -1) {
                DATA_CALCULATOR.incrementByte();
                DATA_CALCULATOR.printOnEachMbDownload();
                fileOutputStream.write(readByte);
                readByte = inputStreamReader.read();
            }
        }
    }``` the above code results in an io exception with message ``` no entry name specified ``` now following java docs ```if there is no context URL and the specification passed to the URL constructor doesn't contain a separator, the URL is considered to refer to a JarFile.```  again if remove the separator !/ it result in a malformed url exception with message ``` add a separator```  does anybody know a way ?

[carmine crescent]

Detected code, here are some useful tools:

[viscid light]

do you consider it as an unsafe cast

[grim lake]

So first of, don't do unsafe cast

[grim lake]

Yes?

Second of, you are asking to just download a file, so just

try(InputStream in = url.openConnection()) {
    Files.copy(in, Path.of("my file.txt));
}

[viscid light]

ok this works but there is a problem a jar file downloaded this way does not contain any sub directories

[grim lake]

Why ?
A jar is a jar

[viscid light]

normally when a .jar file is converted to a .zip file it gives you access to all the sub directories where you can find all the .class files but if i download a .jar file following your method it does not

[grim lake]

Wdym, do you want to download a jar or do you want to extract a jar?

[viscid light]

first i want to download a jar and then extract it

[grim lake]

Right

[grim lake]

Then first do this to download it

Then use JarFile or ZipFile to extract it

[viscid light]

ok

[viscid light]

can i ask java final String[] splittedUrl = (jarUrl.toString().split("/")); final String fileName = splittedUrl[splittedUrl.length - 1]; final File file = new File(directory + fileName); final URLConnection urlConnection = jarUrl.openConnection(); final InputStream inputStream = urlConnection.getInputStream(); final InputStreamReader inputStreamReader = new InputStreamReader(inputStream); try (final FileOutputStream fileOutputStream = new FileOutputStream(file)) { int readByte = inputStreamReader.read(); while (readByte != -1) { fileOutputStream.write(readByte); readByte = inputStreamReader.read(); } } what is wrong with this

this is the error i get when i download a jar file with the method provided above

[grim lake]

Why don't you use my code?

[viscid light]

thanks your code works

i used it