PluginClassLoader.java

package ij.io;
import java.io.*;
import java.net.*;
import java.util.*;
import java.util.zip.*;
import ij.IJ;

public class PluginClassLoader extends ClassLoader {
    protected String path;
    protected Hashtable cache = new Hashtable();
    protected Vector jarFiles;

    public PluginClassLoader(String path) {
        this.path = path;
        jarFiles = new Vector();
        //find all JAR files on the path and subdirectories
        File f = new File(path);
        String[] list = f.list();
        if (list==null)
            return;
        for (int i=0; i<list.length; i++) {
            f=new File(path, list[i]);
            if (f.isDirectory()) {
                String[] innerlist = f.list();
                if (innerlist==null) continue;
                for (int j=0; j<innerlist.length; j++) {
                    File g = new File(f,innerlist[j]);
                    if (g.isFile()) addJAR(g);
                }
            } else 
                addJAR(f);
        }
    }

    private void addJAR(File f) {
        if (f.getName().endsWith(".jar") || f.getName().endsWith(".zip"))
            jarFiles.addElement(f);
    }

    public URL getResource(String name) {
        // try system loader first
        URL res = super.getSystemResource(name);
        if (res != null) return res;

        File resFile;

        //try plugins directory
        try {
            resFile = new File(path, name);
            if (resFile.exists()) {
              res = makeURL(resFile);
              return res; 
            }
        }
        catch (Exception e) {}

        //try subfolders
        resFile = new File(path);
        String[] list = resFile.list();
        if (list!=null) {
            for (int i=0; i<list.length; i++) {
                resFile = new File(path, list[i]);
                if (resFile.isDirectory()) {
                    try {
                        File f = new File(path+list[i], name);
                        if (f.exists()) {
                            res = makeURL(f);
                            return res;
                        }                        
                    }
                    catch (Exception e) {}

                }
            }
        }

        //otherwise look in JAR files
        byte [] resourceBytes;
        for (int i=0; i<jarFiles.size(); i++) {
            try {
                File jf = (File)jarFiles.elementAt(i);
                resourceBytes = loadFromJar(jf.getPath(), name);
                if (resourceBytes != null) {
                    res = makeURL(name, jf);
                    return res;
                }
            }
            catch (MalformedURLException e) {
                IJ.error(e.toString());
            }
            catch (IOException e) {
                IJ.error(e.toString());
            }
        }
        return null;
    }
    
    // make a URL from a file
    private URL makeURL (File fil) throws MalformedURLException {
        URL url = new URL("file","",fil.toString());
        return url;
    }
    
    // make a URL from a file within a JAR
    private URL makeURL (String name, File jar) throws MalformedURLException {
        StringBuffer filename = new StringBuffer("file:///");
        filename.append(jar.toString());
        filename.append("!/");
        filename.append(name);
        //filename.insert(0,'/');
        String sf = filename.toString();
        String sfu = sf.replace('\\','/');
        URL url = new URL("jar","",sfu);
        return url;
    }

    public InputStream getResourceAsStream(String name) {
        //try the system loader first
        InputStream is = super.getSystemResourceAsStream(name);
        if (is != null) return is;

        File resFile;

        //try plugins directory
        resFile = new File(path, name);
        try { // read the byte codes
            is = new FileInputStream(resFile);
        }
        catch (Exception e) {}
        if (is != null) return is;

        //try subdirectories
        resFile = new File(path);
        String[] list = resFile.list();
        if (list!=null) {
            for (int i=0; i<list.length; i++) {
                resFile = new File(path, list[i]);
                if (resFile.isDirectory()) {
                    try {
                        File f = new File(path+list[i], name);
                        is = new FileInputStream(f);
                    }
                    catch (Exception e) {}
                    if (is != null) return is;
                }
            }
        }

        //look in JAR files
        byte [] resourceBytes;
        for (int i=0; i<jarFiles.size(); i++) {
            try {
                File jf = (File)jarFiles.elementAt(i);
                resourceBytes = loadFromJar(jf.getPath(), name);
                if (resourceBytes != null){
                    is = new ByteArrayInputStream(resourceBytes);
                    return is;
                }
            }
            catch (Exception e) {
                IJ.error(e.toString());
            }
        }
        return null;
    }

    public Class loadClass(String className) throws ClassNotFoundException {
        return (loadClass(className, true));
    }

    public synchronized Class loadClass(String className, boolean resolveIt) throws ClassNotFoundException {

        Class   result;
        byte[]  classBytes;

        // try the local cache of classes
        result = (Class)cache.get(className);
        if (result != null) {
            return result;
        }

        // try the system class loader
        try {
            result = super.findSystemClass(className);
            return result;
        }
        catch (Exception e) {}

        // Try to load it from plugins directory
        classBytes = loadClassBytes(className);
        //IJ.log("loadClass: "+ className + "  "+ (classBytes!=null?""+classBytes.length:"null"));
        if (classBytes==null) {
            //IJ.log("ClassNotFoundException");
            throw new ClassNotFoundException(className);
        }

        // Define it (parse the class file)
        result = defineClass(className, classBytes, 0, classBytes.length);
        if (result == null) {
            throw new ClassFormatError();
        }

        //Resolve if necessary
        if (resolveIt) resolveClass(result);

        cache.put(className, result);
        return result;
    }

    protected byte[] loadClassBytes(String name) {
        byte [] classBytes = null;
        classBytes = loadIt(path, name);
        if (classBytes == null) {
            classBytes = loadFromSubdirectory(path, name);
            if (classBytes == null) {
                // Attempt to get the class data from the JAR files.
                for (int i=0; i<jarFiles.size(); i++) {
                    try {
                        File jf = (File)jarFiles.elementAt(i);
                        classBytes = loadClassFromJar(jf.getPath(), name);
                        if (classBytes != null)
                            return classBytes;
                    }
                    catch (Exception e) {
                        //no problem, try the next one
                    }
                }
            }
        }
        return classBytes;
    }

    // Loads the bytes from file
    private byte [] loadIt(String path, String classname) {
        String filename = classname.replace('.','/');
        filename += ".class";
        File fullname = new File(path, filename);
        //ij.IJ.write("loadIt: " + fullname);
        try { // read the byte codes
            InputStream is = new FileInputStream(fullname);
            int bufsize = (int)fullname.length();
            byte buf[] = new byte[bufsize];
            is.read(buf, 0, bufsize);
            is.close();
            return buf;
        } catch (Exception e) {
            return null;
        }
    }

    private byte [] loadFromSubdirectory(String path, String name) {
        File f = new File(path);
        String[] list = f.list();
        if (list!=null) {
            for (int i=0; i<list.length; i++) {
                //ij.IJ.write(path+"  "+list[i]);
                f=new File(path, list[i]);
                if (f.isDirectory()) {
                    byte [] buf = loadIt(path+list[i], name);
                    if (buf!=null)
                        return buf;
                }
            }
        }
        return null;
    }

    // Load class from a JAR file
    byte[] loadClassFromJar(String jar, String className) {
        String name = className.replace('.','/');
        name += ".class";
        return loadFromJar(jar, name);
    }

    // Load class or resource from a JAR file
    byte[] loadFromJar(String jar, String name) {
        BufferedInputStream bis = null;
        try {
            ZipFile jarFile = new ZipFile(jar);
            Enumeration entries = jarFile.entries();
            while (entries.hasMoreElements()) {
                ZipEntry entry = (ZipEntry) entries.nextElement();
                if (entry.getName().equals(name)) {
                    bis = new BufferedInputStream(jarFile.getInputStream(entry));
                    int size = (int)entry.getSize();
                    byte[] data = new byte[size];
                    int b=0, eofFlag=0;
                    while ((size - b) > 0) {
                        eofFlag = bis.read(data, b, size - b);
                        if (eofFlag==-1) break;
                        b += eofFlag;
                    }
                    return data;
                }
            }
        }
        catch (Exception e) {}
        finally {
            try {if (bis!=null) bis.close();}
            catch (IOException e) {}
        }
        return null;
    }

}