Tentukan dari mana file JAR berasal

Saya tidak di depan IDE sekarang, hanya melihat spesifikasi API.

CodeSource src = MyClass.class.getProtectionDomain().getCodeSource();
if (src != null) {
    URL jar = src.getLocation();
}

Saya ingin menentukan dari mana file JAR berasal. Apakah ini cara untuk melakukannya?

Iya. Ini bekerja untuk semua kelas kecuali kelas yang dimuat oleh bootstrap classloader. Cara lain untuk menentukan adalah:

Class klass = String.class;
URL location = klass.getResource('/' + klass.getName().replace('.', '/') + ".class");

Sebagai notnoop menunjukkan klass.getResource()metode mengembalikan lokasi file kelas itu sendiri. Sebagai contoh:

jar:file:/jdk/jre/lib/rt.jar!/java/lang/String.class
file:/projects/classes/pkg/MyClass$1.class

The getProtectionDomain().getCodeSource().getLocation()Metode mengembalikan lokasi file jar atau CLASSPATH

file:/Users/home/java/libs/ejb3-persistence-1.0.2.GA.jar
file:/projects/classes

Lihat LiveInjector.findPathJar()dari Lombok PatcherLiveInjector.java . Perhatikan bahwa ini merupakan kasus khusus di mana file tersebut tidak benar-benar hidup dalam toples, dan Anda mungkin ingin mengubahnya.

/**
 * If the provided class has been loaded from a jar file that is on the local file system, will find the absolute path to that jar file.
 * 
 * @param context The jar file that contained the class file that represents this class will be found. Specify {@code null} to let {@code LiveInjector}
 *                find its own jar.
 * @throws IllegalStateException If the specified class was loaded from a directory or in some other way (such as via HTTP, from a database, or some
 *                               other custom classloading device).
 */
public static String findPathJar(Class<?> context) throws IllegalStateException {
    if (context == null) context = LiveInjector.class;
    String rawName = context.getName();
    String classFileName;
    /* rawName is something like package.name.ContainingClass$ClassName. We need to turn this into ContainingClass$ClassName.class. */ {
        int idx = rawName.lastIndexOf('.');
        classFileName = (idx == -1 ? rawName : rawName.substring(idx+1)) + ".class";
    }

    String uri = context.getResource(classFileName).toString();
    if (uri.startsWith("file:")) throw new IllegalStateException("This class has been loaded from a directory and not from a jar file.");
    if (!uri.startsWith("jar:file:")) {
        int idx = uri.indexOf(':');
        String protocol = idx == -1 ? "(unknown)" : uri.substring(0, idx);
        throw new IllegalStateException("This class has been loaded remotely via the " + protocol +
                " protocol. Only loading from a jar on the local file system is supported.");
    }

    int idx = uri.indexOf('!');
    //As far as I know, the if statement below can't ever trigger, so it's more of a sanity check thing.
    if (idx == -1) throw new IllegalStateException("You appear to have loaded this class from a local jar file, but I can't make sense of the URL!");

    try {
        String fileName = URLDecoder.decode(uri.substring("jar:file:".length(), idx), Charset.defaultCharset().name());
        return new File(fileName).getAbsolutePath();
    } catch (UnsupportedEncodingException e) {
        throw new InternalError("default charset doesn't exist. Your VM is borked.");
    }
}

Menggunakan

String path = <Any of your class within the jar>.class.getProtectionDomain().getCodeSource().getLocation().getPath(); 

Jika ini berisi beberapa entri maka lakukan beberapa operasi substring.

private String resourceLookup(String lookupResourceName) {



    try {

        if (lookupResourceName == null || lookupResourceName.length()==0) {
            return "";
        }
        // "/java/lang/String.class"

        // Check if entered data was in java class name format
        if (lookupResourceName.indexOf("/")==-1) {
            lookupResourceName = lookupResourceName.replaceAll("[.]", "/");
            lookupResourceName =  "/" + lookupResourceName + ".class";
        }

        URL url = this.getClass().getResource(lookupResourceName);
        if (url == null) {
            return("Unable to locate resource "+ lookupResourceName);

        }

        String resourceUrl = url.toExternalForm();

        Pattern pattern =
            Pattern.compile("(zip:|jar:file:/)(.*)!/(.*)", Pattern.CASE_INSENSITIVE);

        String jarFilename = null;
        String resourceFilename = null;
        Matcher m = pattern.matcher(resourceUrl);
        if (m.find()) {
            jarFilename = m.group(2);
            resourceFilename = m.group(3);
        } else {
            return "Unable to parse URL: "+ resourceUrl;

        }

        if (!jarFilename.startsWith("C:") ){
          jarFilename = "/"+jarFilename;  // make absolute path on Linux
        }

        File file = new File(jarFilename);
        Long jarSize=null;
        Date jarDate=null;
        Long resourceSize=null;
        Date resourceDate=null;
        if (file.exists() && file.isFile()) {

            jarSize = file.length();
            jarDate = new Date(file.lastModified());

            try {
                JarFile jarFile = new JarFile(file, false);
                ZipEntry entry = jarFile.getEntry(resourceFilename);
                resourceSize = entry.getSize();
                resourceDate = new Date(entry.getTime());
            } catch (Throwable e) {
                return ("Unable to open JAR" + jarFilename + "   "+resourceUrl +"\n"+e.getMessage());

            }

           return "\nresource: "+resourceFilename+"\njar: "+jarFilename + "  \nJarSize: " +jarSize+"  \nJarDate: " +jarDate.toString()+"  \nresourceSize: " +resourceSize+"  \nresourceDate: " +resourceDate.toString()+"\n";


        } else {
            return("Unable to load jar:" + jarFilename+ "  \nUrl: " +resourceUrl);

        }
    } catch (Exception e){
        return e.getMessage();
    }


}