Java Class from Package getClasses(String packageName)

Description

Scans all classes accessible from the context class loader which belong to the given package and subpackages.

License

LGPL

Parameter

Parameter	Description
packageName	The base package

Exception

Parameter	Description
ClassNotFoundException	an exception
IOException	an exception

Return

The classes

Declaration

@SuppressWarnings("unchecked")
private static List<Class> getClasses(String packageName) throws ClassNotFoundException, IOException 

Method Source Code

//package com.java2s;
//License from project: LGPL 

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.net.URLDecoder;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;

public class Main {
    /**//from  w  ww .j  a  v  a  2  s .  c o m
     * Scans all classes accessible from the context class loader which belong to the given package and subpackages.
     *
     * @param packageName The base package
     * @return The classes
     * @throws ClassNotFoundException
     * @throws IOException
     */
    @SuppressWarnings("unchecked")
    private static List<Class> getClasses(String packageName) throws ClassNotFoundException, IOException {
        ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
        assert classLoader != null;
        String path = packageName.replace('.', '/');
        Enumeration<URL> resources = classLoader.getResources(path);
        List<File> dirs = new ArrayList<File>();
        while (resources.hasMoreElements()) {
            URL resource = resources.nextElement();
            String fileName = resource.getFile();
            String fileNameDecoded = URLDecoder.decode(fileName, "UTF-8");
            dirs.add(new File(fileNameDecoded));
        }
        ArrayList<Class> classes = new ArrayList<Class>();
        for (File directory : dirs) {
            classes.addAll(findClasses(directory, packageName));
        }
        return classes;
    }

    /**
     * Recursive method used to find all classes in a given directory and subdirs.
     *
     * @param directory   The base directory
     * @param packageName The package name for classes found inside the base directory
     * @return The classes
     * @throws ClassNotFoundException
     */
    @SuppressWarnings("unchecked")
    private static List<Class> findClasses(File directory, String packageName) throws ClassNotFoundException {
        List<Class> classes = new ArrayList<Class>();
        if (!directory.exists()) {
            return classes;
        }
        File[] files = directory.listFiles();
        for (File file : files) {
            String fileName = file.getName();
            if (file.isDirectory()) {
                assert !fileName.contains(".");
                classes.addAll(findClasses(file, packageName + "." + fileName));
            } else if (fileName.endsWith(".class") && !fileName.contains("$")) {
                Class _class;
                try {
                    _class = Class.forName(packageName + '.' + fileName.substring(0, fileName.length() - 6));
                } catch (ExceptionInInitializerError e) {
                    // happen, for example, in classes, which depend on 
                    // Spring to inject some beans, and which fail, 
                    // if dependency is not fulfilled
                    _class = Class.forName(packageName + '.' + fileName.substring(0, fileName.length() - 6), false,
                            Thread.currentThread().getContextClassLoader());
                }
                classes.add(_class);
            }
        }
        return classes;
    }
}

Related

1. getClasses(String packageName)
2. getClasses(String packageName)
3. getClasses(String packageName)
4. getClasses(String packageName)
5. getClasses(String packageName)
6. getClasses(String packageName)
7. getClasses(String packageName, Class inheritedType)
8. getClasses(String pckgname)
9. getClasses(String pckgname)