Java Class from Package getClassesInPackage(String packageName)

Description

get Classes In Package

License

Open Source License

Declaration

@SuppressWarnings("resource")
    public static List<Class<?>> getClassesInPackage(String packageName) throws IOException 

Method Source Code

//package com.java2s;
//License from project: Open Source License 

import java.io.*;
import java.net.*;

import java.util.*;
import java.util.jar.*;

public class Main {
    @SuppressWarnings("resource")
    public static List<Class<?>> getClassesInPackage(String packageName) throws IOException {
        ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
        List<Class<?>> classes = new ArrayList<Class<?>>();
        URL packageURL;/*www  .  j av  a2s  . c  o m*/

        packageURL = classLoader.getResource(packageName.replace(".", "/"));

        if (packageURL.getProtocol().equals("jar")) {
            packageName = packageName.replace(".", "/");
            String jarFileName;
            JarFile jf;
            Enumeration<JarEntry> jarEntries;
            String entryName;

            // build jar file name, then loop through zipped entries
            jarFileName = URLDecoder.decode(packageURL.getFile(), "UTF-8");
            jarFileName = jarFileName.substring(5, jarFileName.indexOf("!"));
            jf = new JarFile(jarFileName);
            jarEntries = jf.entries();
            while (jarEntries.hasMoreElements()) {
                entryName = jarEntries.nextElement().getName();
                if (entryName.startsWith(packageName) && entryName.length() > packageName.length() + 5) {
                    entryName = entryName.replace('/', '.');
                    entryName = entryName.substring(0, entryName.lastIndexOf('.'));
                    try {
                        classes.add(Class.forName(entryName));
                    } catch (ClassNotFoundException exception) {
                        exception.printStackTrace();
                    }
                }
            }

            // loop through files in classpath
        } else {
            try {
                Iterable<Class<?>> classesFromFile = getClasses(packageName);
                for (Class<?> c : classesFromFile)
                    classes.add(c);
            } catch (ClassNotFoundException exception) {
                exception.printStackTrace();
            }
        }
        return classes;
    }

    /**
     * Scans all classes accessible from the context class loader which belong
     * to the given package and sub packages.
     * 
     * @author Paulius Matulionis - stackoverflow.com
     * @param packageName
     *            the base package
     * @return The classes
     * @throws ClassNotFoundException
     *             if class not found exception occurs
     * @throws IOException
     *             if IO error occurs
     */
    private static Iterable<Class<?>> getClasses(String packageName) throws ClassNotFoundException, IOException {
        ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
        String path = packageName.replace('.', '/');
        Enumeration<URL> resources = classLoader.getResources(path);
        LinkedList<File> dirs = new LinkedList<File>();
        while (resources.hasMoreElements()) {
            URL resource = resources.nextElement();
            dirs.add(new File(resource.getFile()));
        }
        LinkedList<Class<?>> classes = new LinkedList<Class<?>>();
        for (File directory : dirs) {
            classes.addAll(findClasses(directory, packageName));
        }
        return classes;
    }

    /**
     * Recursive method used to find all classes in a given directory and sub
     * directories.
     * 
     * @author Paulius Matulionis - stackoverflow.com
     * @param directory
     *            the base directory
     * @param packageName
     *            the package name for classes found inside the base directory
     * @return the classes
     * @throws ClassNotFoundException
     *             if class not found exception occurrs
     */
    private static LinkedList<Class<?>> findClasses(File directory, String packageName)
            throws ClassNotFoundException {
        LinkedList<Class<?>> classes = new LinkedList<Class<?>>();
        if (!directory.exists()) {
            return classes;
        }
        File[] files = directory.listFiles();
        if (files != null) {
            for (File file : files) {
                if (file.isDirectory()) {
                    classes.addAll(findClasses(file, packageName + "." + file.getName()));
                } else if (file.getName().endsWith(".class")) {
                    classes.add(Class
                            .forName(packageName + '.' + file.getName().substring(0, file.getName().length() - 6)));
                }
            }
        }
        return classes;
    }
}

Related

1. getClassesForPackage(String packageName)
2. getClassesForPackage(String packageName)
3. getClassesForPackage(String pckgname)
4. getClassesForPackage(String pckgname)
5. getClassesInPackage(String packageName)
6. getClassesInPackage(String packageName)
7. getClassesInPackage(String pckgname)
8. getClassesInPackage(String targetPackage)
9. getClassNameByPackage(String packageName)