print a class in which jar file.

TestGetClassFromWhichJarLocation.java

import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.security.CodeSource;
import java.security.ProtectionDomain;

/**
 * Creted on 2018/2/8.
 */
public class TestGetClassFromWhichJarLocation {

    public static void main(String[] args) {
        try {
            Class<?> cls = Class.forName("java.lang.String");
            URL classLocation = getClassLocation(cls);
            System.out.println(classLocation);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    public static URL getClassLocation(final Class cls) {
        if (cls == null) {
            throw new IllegalArgumentException("null input: cls");
        }
        URL result = null;
        final String clsAsResource = cls.getName().replace('.', '/').concat(".class");
        final ProtectionDomain pd = cls.getProtectionDomain();
        if (pd != null) {
            final CodeSource cs = pd.getCodeSource();
            if (cs != null) result = cs.getLocation();
            if (result != null) {
                if ("file".equals(result.getProtocol())) {
                    try {
                        if (result.toExternalForm().endsWith(".jar") || result.toExternalForm().endsWith(".zip"))
                            result = new URL("jar:".concat(result.toExternalForm()).concat("!/").concat(clsAsResource));
                        else if (new File(result.getFile()).isDirectory()) {
                            result = new URL(result, clsAsResource);
                        }
                    } catch (MalformedURLException ignore) {
                        ignore.printStackTrace();
                    }
                }
            }
        }
        if (result == null) {
            final ClassLoader clsLoader = cls.getClassLoader();
            result = clsLoader != null ?
                    clsLoader.getResource(clsAsResource) :
                    ClassLoader.getSystemResource(clsAsResource);
        }
        return result;
    }

}