jaxp/src/java.xml/share/classes/com/sun/org/apache/bcel/internal/util/ClassLoader.java
changeset 25868 686eef1e7a79
parent 12457 c348e06f0e82
child 44797 8b3b3b911b8a
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jaxp/src/java.xml/share/classes/com/sun/org/apache/bcel/internal/util/ClassLoader.java	Sun Aug 17 15:51:56 2014 +0100
@@ -0,0 +1,224 @@
+/*
+ * reserved comment block
+ * DO NOT REMOVE OR ALTER!
+ */
+package com.sun.org.apache.bcel.internal.util;
+
+/* ====================================================================
+ * The Apache Software License, Version 1.1
+ *
+ * Copyright (c) 2001 The Apache Software Foundation.  All rights
+ * reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. The end-user documentation included with the redistribution,
+ *    if any, must include the following acknowledgment:
+ *       "This product includes software developed by the
+ *        Apache Software Foundation (http://www.apache.org/)."
+ *    Alternately, this acknowledgment may appear in the software itself,
+ *    if and wherever such third-party acknowledgments normally appear.
+ *
+ * 4. The names "Apache" and "Apache Software Foundation" and
+ *    "Apache BCEL" must not be used to endorse or promote products
+ *    derived from this software without prior written permission. For
+ *    written permission, please contact apache@apache.org.
+ *
+ * 5. Products derived from this software may not be called "Apache",
+ *    "Apache BCEL", nor may "Apache" appear in their name, without
+ *    prior written permission of the Apache Software Foundation.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ * ====================================================================
+ *
+ * This software consists of voluntary contributions made by many
+ * individuals on behalf of the Apache Software Foundation.  For more
+ * information on the Apache Software Foundation, please see
+ * <http://www.apache.org/>.
+ */
+
+import java.util.Hashtable;
+import java.io.*;
+import com.sun.org.apache.bcel.internal.*;
+import com.sun.org.apache.bcel.internal.classfile.*;
+
+/**
+ * <p>Drop in replacement for the standard class loader of the JVM. You can use it
+ * in conjunction with the JavaWrapper to dynamically modify/create classes
+ * as they're requested.</p>
+ *
+ * <p>This class loader recognizes special requests in a distinct
+ * format, i.e., when the name of the requested class contains with
+ * "$$BCEL$$" it calls the createClass() method with that name
+ * (everything bevor the $$BCEL$$ is considered to be the package
+ * name. You can subclass the class loader and override that
+ * method. "Normal" classes class can be modified by overriding the
+ * modifyClass() method which is called just before defineClass().</p>
+ *
+ * <p>There may be a number of packages where you have to use the default
+ * class loader (which may also be faster). You can define the set of packages
+ * where to use the system class loader in the constructor. The default value contains
+ * "java.", "sun.", "javax."</p>
+ *
+ * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
+ * @see JavaWrapper
+ * @see ClassPath
+ */
+public class ClassLoader extends java.lang.ClassLoader {
+  private Hashtable classes = new Hashtable(); // Hashtable is synchronized thus thread-safe
+  private String[] ignored_packages = {
+    "java.", "javax.", "sun."
+  };
+  private Repository repository = SyntheticRepository.getInstance();
+  private java.lang.ClassLoader deferTo = ClassLoader.getSystemClassLoader();
+
+  public ClassLoader() {
+  }
+
+  public ClassLoader(java.lang.ClassLoader deferTo) {
+    this.deferTo = deferTo;
+    this.repository = new ClassLoaderRepository(deferTo);
+  }
+
+  /** @param ignored_packages classes contained in these packages will be loaded
+   * with the system class loader
+   */
+  public ClassLoader(String[] ignored_packages) {
+    addIgnoredPkgs(ignored_packages);
+  }
+
+  public ClassLoader(java.lang.ClassLoader deferTo, String [] ignored_packages) {
+    this.deferTo = deferTo;
+    this.repository = new ClassLoaderRepository(deferTo);
+
+    addIgnoredPkgs(ignored_packages);
+  }
+
+  private void addIgnoredPkgs(String[] ignored_packages) {
+    String[] new_p = new String[ignored_packages.length + this.ignored_packages.length];
+
+    System.arraycopy(this.ignored_packages, 0, new_p, 0, this.ignored_packages.length);
+    System.arraycopy(ignored_packages, 0, new_p, this.ignored_packages.length,
+                     ignored_packages.length);
+
+    this.ignored_packages = new_p;
+  }
+
+  protected Class loadClass(String class_name, boolean resolve)
+    throws ClassNotFoundException
+  {
+    Class cl = null;
+
+    /* First try: lookup hash table.
+     */
+    if((cl=(Class)classes.get(class_name)) == null) {
+      /* Second try: Load system class using system class loader. You better
+       * don't mess around with them.
+       */
+      for(int i=0; i < ignored_packages.length; i++) {
+        if(class_name.startsWith(ignored_packages[i])) {
+          cl = deferTo.loadClass(class_name);
+          break;
+        }
+      }
+
+      if(cl == null) {
+        JavaClass clazz = null;
+
+        /* Third try: Special request?
+         */
+        if(class_name.indexOf("$$BCEL$$") >= 0)
+          clazz = createClass(class_name);
+        else { // Fourth try: Load classes via repository
+          if ((clazz = repository.loadClass(class_name)) != null) {
+            clazz = modifyClass(clazz);
+          }
+          else
+            throw new ClassNotFoundException(class_name);
+        }
+
+        if(clazz != null) {
+          byte[] bytes  = clazz.getBytes();
+          cl = defineClass(class_name, bytes, 0, bytes.length);
+        } else // Fourth try: Use default class loader
+          cl = Class.forName(class_name);
+      }
+
+      if(resolve)
+        resolveClass(cl);
+    }
+
+    classes.put(class_name, cl);
+
+    return cl;
+  }
+
+  /** Override this method if you want to alter a class before it gets actually
+   * loaded. Does nothing by default.
+   */
+  protected JavaClass modifyClass(JavaClass clazz) {
+    return clazz;
+  }
+
+  /**
+   * Override this method to create you own classes on the fly. The
+   * name contains the special token $$BCEL$$. Everything before that
+   * token is consddered to be a package name. You can encode you own
+   * arguments into the subsequent string. You must regard however not
+   * to use any "illegal" characters, i.e., characters that may not
+   * appear in a Java class name too<br>
+   *
+   * The default implementation interprets the string as a encoded compressed
+   * Java class, unpacks and decodes it with the Utility.decode() method, and
+   * parses the resulting byte array and returns the resulting JavaClass object.
+   *
+   * @param class_name compressed byte code with "$$BCEL$$" in it
+   */
+  protected JavaClass createClass(String class_name) {
+    int    index     = class_name.indexOf("$$BCEL$$");
+    String real_name = class_name.substring(index + 8);
+
+    JavaClass clazz = null;
+    try {
+      byte[]      bytes  = Utility.decode(real_name, true);
+      ClassParser parser = new ClassParser(new ByteArrayInputStream(bytes), "foo");
+
+      clazz = parser.parse();
+    } catch(Throwable e) {
+      e.printStackTrace();
+      return null;
+    }
+
+    // Adapt the class name to the passed value
+    ConstantPool cp = clazz.getConstantPool();
+
+    ConstantClass cl = (ConstantClass)cp.getConstant(clazz.getClassNameIndex(),
+                                                     Constants.CONSTANT_Class);
+    ConstantUtf8 name = (ConstantUtf8)cp.getConstant(cl.getNameIndex(),
+                                                     Constants.CONSTANT_Utf8);
+    name.setBytes(class_name.replace('.', '/'));
+
+    return clazz;
+  }
+}