Java Class from Package getClassesForPackage(String packageName)

Description

get Classes For Package

License

Apache License

Declaration

public static List<Class<?>> getClassesForPackage(String packageName) throws ClassNotFoundException 

Method Source Code

//package com.java2s;
/**/*from   w ww .  ja va2 s .c o m*/
 * Copyright 2014 AnjLab
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.io.File;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.JarURLConnection;
import java.net.URL;
import java.net.URLDecoder;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.List;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;

public class Main {
    public static List<Class<?>> getClassesForPackage(String packageName) throws ClassNotFoundException {
        // This will hold a list of directories matching the packageName.
        // There may be more than one if a package is split over multiple
        // jars/paths
        List<Class<?>> classes = new ArrayList<Class<?>>();
        List<File> directories = new ArrayList<File>();
        try {
            ClassLoader cld = Thread.currentThread().getContextClassLoader();
            if (cld == null) {
                throw new ClassNotFoundException("Can't get class loader.");
            }
            // Ask for all resources for the path
            Enumeration<URL> resources = cld.getResources(packageName.replace('.', '/'));
            while (resources.hasMoreElements()) {
                URL res = resources.nextElement();
                if (res.getProtocol().equalsIgnoreCase("jar")) {
                    JarURLConnection conn = (JarURLConnection) res.openConnection();
                    JarFile jar = conn.getJarFile();
                    for (JarEntry e : Collections.list(jar.entries())) {

                        if (e.getName().startsWith(packageName.replace('.', '/')) && e.getName().endsWith(".class")
                                && !e.getName().contains("$")) {
                            String className = e.getName().replace("/", ".").substring(0,
                                    e.getName().length() - ".class".length());
                            classes.add(Class.forName(className));
                        }
                    }
                } else {
                    directories.add(new File(URLDecoder.decode(res.getPath(), "UTF-8")));
                }
            }
        } catch (NullPointerException x) {
            throw new ClassNotFoundException(
                    packageName + " does not appear to be " + "a valid package (Null pointer exception)");
        } catch (UnsupportedEncodingException encex) {
            throw new ClassNotFoundException(
                    packageName + " does not appear to be " + "a valid package (Unsupported encoding)");
        } catch (IOException ioex) {
            throw new ClassNotFoundException(
                    "IOException was thrown when trying " + "to get all resources for " + packageName);
        }

        // For every directory identified capture all the .class files
        for (File directory : directories) {
            if (directory.exists()) {
                // Get the list of the files contained in the package
                String[] files = directory.list();
                for (String file : files) {
                    // we are only interested in .class files
                    if (file.endsWith(".class")) {
                        // removes the .class extension
                        classes.add(Class.forName(packageName + '.' + file.substring(0, file.length() - 6)));
                    }
                }
            } else {
                throw new ClassNotFoundException(
                        packageName + " (" + directory.getPath() + ") does not appear to be a valid package");
            }
        }
        return classes;
    }
}

Related

1. getClasses(String pckgname)
2. getClasses(String pkg)
3. getClasses(String pkg)
4. getClassesForPackage(final String packageName)
5. getClassesForPackage(Package pkg)
6. getClassesForPackage(String packageName)
7. getClassesForPackage(String pckgname)
8. getClassesForPackage(String pckgname)
9. getClassesInPackage(String packageName)