Java ClassPath fillClassPath(ClassLoader cl, StringBuffer classpath)

Description

Walk the classloader hierarchy and add to the classpath

License

Apache License

Parameter

Parameter	Description
cl	a parameter
classpath	a parameter

Declaration

private static void fillClassPath(ClassLoader cl, StringBuffer classpath) 

Method Source Code

//package com.java2s;
/*//from  w ww . j  a va  2 s. co  m
 * ClasspathUtils.java
 * 
 * Copyright 2001-2004 The Apache Software Foundation.
 * 
 * 
 * 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.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

import java.net.URL;
import java.net.URLClassLoader;
import java.net.URLDecoder;
import java.util.StringTokenizer;
import java.util.jar.Attributes;
import java.util.jar.JarFile;
import java.util.jar.JarInputStream;
import java.util.jar.Manifest;

public class Main {
    /**
     * Walk the classloader hierarchy and add to the classpath
     * @param cl
     * @param classpath
     */
    private static void fillClassPath(ClassLoader cl, StringBuffer classpath) {
        while (cl != null) {
            if (cl instanceof URLClassLoader) {
                URL[] urls = ((URLClassLoader) cl).getURLs();
                for (int i = 0; (urls != null) && i < urls.length; i++) {
                    String path = urls[i].getPath();
                    //If it is a drive letter, adjust accordingly.
                    if (path.length() >= 3 && path.charAt(0) == '/'
                            && path.charAt(2) == ':')
                        path = path.substring(1);
                    classpath.append(URLDecoder.decode(path));
                    classpath.append(File.pathSeparatorChar);

                    // if its a jar extract Class-Path entries from manifest
                    File file = new File(urls[i].getFile());
                    if (file.isFile()) {
                        FileInputStream fis = null;
                        try {
                            fis = new FileInputStream(file);
                            if (isJar(fis)) {
                                JarFile jar = new JarFile(file);
                                Manifest manifest = jar.getManifest();
                                if (manifest != null) {
                                    Attributes attributes = manifest
                                            .getMainAttributes();
                                    if (attributes != null) {
                                        String s = attributes
                                                .getValue(Attributes.Name.CLASS_PATH);
                                        String base = file.getParent();
                                        if (s != null) {
                                            StringTokenizer st = new StringTokenizer(
                                                    s, " ");
                                            while (st.hasMoreTokens()) {
                                                String t = st.nextToken();
                                                classpath
                                                        .append(base
                                                                + File.separatorChar
                                                                + t);
                                                classpath
                                                        .append(File.pathSeparatorChar);
                                            }
                                        }
                                    }
                                }
                            }
                        } catch (IOException ioe) {
                        } finally {
                            if (fis != null) {
                                try {
                                    fis.close();
                                } catch (IOException ioe2) {
                                }
                            }
                        }
                    }
                }
            }
            cl = cl.getParent();
        }
    }

    /**
     * Check if this inputstream is a jar/zip
     * @param is
     * @return true if inputstream is a jar
     */
    public static boolean isJar(InputStream is) {
        try {
            JarInputStream jis = new JarInputStream(is);
            if (jis.getNextEntry() != null) {
                return true;
            }
        } catch (IOException ioe) {
        }
        return false;
    }
}

Related

1. createClassLoader(List libs, boolean useSystemClassPath)
2. createClassPath(File file)
3. dumpClasspath(ClassLoader loader)
4. existsInClasspath(Class clazz, String fileName)
5. existsInClasspath(final String fileName)
6. findClassPaths()
7. findClassPaths()
8. findClasspathsByLoader(ClassLoader loader)
9. findClassPathsToEn()