class ClassLoaderFactory

class ClassLoaderFactory

package org.apache.catalina.startup; import java.io.File; import java.io.IOException; import java.net.URL; import java.util.ArrayList; import java.util.jar.JarEntry; import java.util.jar.JarFile; import org.apache.catalina.loader.StandardClassLoader;  /** * Utility class for building class loaders for Catalina. The factory * method requires the following parameters in order to build a new class * loader (with suitable defaults in all cases): 

• A set of directories containing unpacked classes (and resources) that should be included in the class loader's repositories.
• A set of directories containing classes and resources in JAR files. Each readable JAR file discovered in these directories will be added to the class loader's repositories.
• ClassLoader instance that should become the parent of the new class loader.

 * * @author Craig R. McClanahan * @version $Revision: 1.8 $ $Date: 2002/02/17 08:26:02 $ */  public final class ClassLoaderFactory {  /** * Debugging detail level for processing the startup. */  private static int debug = 0;  /** * Return the debugging detail level. */  public static int getDebug() { return (debug); }  /** * 设置DEBUG级别 */  public static void setDebug(int newDebug) { debug = newDebug; }  /** * 该类是一个静态类，用来创建和返回ClassLoader对象（实际上是StandardClassLoader对象） * 它将根据设置和参数返回apache定置的ClassLoader对象，以完成自己的类载入 * * @param unpacked 类路径CLASSPATH的数组 * @param packed 含有JAR文件的类路径 * @param parent 父ClassLoader对象。当一个ClassLoader对象无法完成类载入时，它将请求父对象帮助 * * @exception Exception if an error occurs constructing the class loader */  public static ClassLoader createClassLoader(File unpacked[], File packed[], ClassLoader parent) throws Exception { if (debug >= 1) log("Creating new class loader");  // list里将被填入所有需要附加到CLASSPATH上去的文件名  ArrayList list = new ArrayList();  // Add unpacked directories  if (unpacked != null) { for (int i = 0; i < unpacked.length; i++) { File file = unpacked[i]; if (!file.isDirectory() || !file.exists() || !file.canRead()) continue; if (debug >= 1) log(" Including directory " + file.getAbsolutePath()); URL url = new URL("file", null, file.getCanonicalPath() + File.separator); list.add(url.toString()); } }  // Add packed directory JAR files  if (packed != null) { for (int i = 0; i < packed.length; i++) { File directory = packed[i]; if (!directory.isDirectory() || !directory.exists() || !directory.canRead()) continue; String filenames[] = directory.list(); for (int j = 0; j < filenames.length; j++) { String filename = filenames[j].toLowerCase(); if (!filename.endsWith(".jar")) continue; File file = new File(directory, filenames[j]); if (debug >= 1) log(" Including jar file " + file.getAbsolutePath()); URL url = new URL("file", null, file.getCanonicalPath()); list.add(url.toString()); } } }  // 填好了list   // 创建StandardClassLoader对象，并返回  String array[] = (String[]) list.toArray(new String[list.size()]); StandardClassLoader classLoader = null; if (parent == null) classLoader = new StandardClassLoader(array); else classLoader = new StandardClassLoader(array, parent); classLoader.setDelegate(true); return (classLoader); }  /** * 输出日志 */  private static void log(String message) { System.out.print("ClassLoaderFactory: "); System.out.println(message); }  /** * 输出日志和异常信息 */  private static void log(String message, Throwable exception) { log(message); exception.printStackTrace(System.out); } }