ClasspathClassLoader xref
1 /**
2 * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
3 */
4 package net.sourceforge.pmd.util;
5
6 import java.io.BufferedReader;
7 import java.io.File;
8 import java.io.IOException;
9 import java.io.InputStreamReader;
10 import java.net.MalformedURLException;
11 import java.net.URL;
12 import java.net.URLClassLoader;
13 import java.util.ArrayList;
14 import java.util.List;
15 import java.util.StringTokenizer;
16 import java.util.logging.Level;
17 import java.util.logging.Logger;
18
19 import org.apache.commons.io.IOUtils;
20
21 /**
22 * Create a ClassLoader which loads classes using a CLASSPATH like String.
23 * If the String looks like a URL to a file (e.g. starts with <code>file://</code>)
24 * the file will be read with each line representing an path on the classpath.
25 *
26 * @author Edwin Chan
27 */
28 public class ClasspathClassLoader extends URLClassLoader {
29
30 private static final Logger LOG = Logger.getLogger(ClasspathClassLoader.class.getName());
31
32 public ClasspathClassLoader(String classpath, ClassLoader parent) throws IOException {
33 super(initURLs(classpath), parent);
34 }
35
36 private static URL[] initURLs(String classpath) throws IOException {
37 if (classpath == null) {
38 throw new IllegalArgumentException("classpath argument cannot be null");
39 }
40 final List<URL> urls = new ArrayList<URL>();
41 if (classpath.startsWith("file://")) {
42 // Treat as file URL
43 addFileURLs(urls, new URL(classpath));
44 } else {
45 // Treat as classpath
46 addClasspathURLs(urls, classpath);
47 }
48 return urls.toArray(new URL[urls.size()]);
49 }
50
51 private static void addClasspathURLs(final List<URL> urls, final String classpath) throws MalformedURLException {
52 StringTokenizer toker = new StringTokenizer(classpath, File.pathSeparator);
53 while (toker.hasMoreTokens()) {
54 String token = toker.nextToken();
55 LOG.log(Level.FINE, "Adding classpath entry: <{0}>", token);
56 urls.add(createURLFromPath(token));
57 }
58 }
59
60 private static void addFileURLs(List<URL> urls, URL fileURL) throws IOException {
61 BufferedReader in = null;
62 try {
63 in = new BufferedReader(new InputStreamReader(fileURL.openStream()));
64 String line;
65 while ((line = in.readLine()) != null) {
66 LOG.log(Level.FINE, "Read classpath entry line: <{0}>", line);
67 line = line.trim();
68 if (line.length() > 0) {
69 LOG.log(Level.FINE, "Adding classpath entry: <{0}>", line);
70 urls.add(createURLFromPath(line));
71 }
72 }
73 } finally {
74 IOUtils.closeQuietly(in);
75 }
76 }
77
78 private static URL createURLFromPath(String path) throws MalformedURLException {
79 File file = new File(path);
80 return file.getAbsoluteFile().toURI().toURL();
81 }
82
83 /**
84 * {@inheritDoc}
85 */
86 @Override
87 public String toString() {
88 StringBuilder sb = new StringBuilder(getClass().getSimpleName());
89 sb.append("[[");
90 StringUtil.asStringOn(sb, getURLs(), ":");
91 sb.append("] parent: ");
92 sb.append(getParent());
93 sb.append(']');
94
95 return sb.toString();
96 }
97 }