Package org.springframework.core.io

Source Code of org.springframework.core.io.VfsUtils

/*
* Copyright 2002-2012 the original author or authors.
*
* 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.
*/

package org.springframework.core.io;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.URI;
import java.net.URL;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.core.NestedIOException;
import org.springframework.util.ReflectionUtils;

/**
* Utility for detecting the JBoss VFS version available in the classpath.
* JBoss AS 5+ uses VFS 2.x (package <code>org.jboss.virtual</code>) while
* JBoss AS 6+ uses VFS 3.x (package <code>org.jboss.vfs</code>).
*
* <p>Thanks go to Marius Bogoevici for the initial patch.
*
* <b>Note:</b> This is an internal class and should not be used outside the framework.
*
* @author Costin Leau
* @since 3.0.3
*/
public abstract class VfsUtils {

  private static final Log logger = LogFactory.getLog(VfsUtils.class);

  private static final String VFS2_PKG = "org.jboss.virtual.";
  private static final String VFS3_PKG = "org.jboss.vfs.";
  private static final String VFS_NAME = "VFS";

  private static enum VFS_VER { V2, V3 }

  private static VFS_VER version;

  private static Method VFS_METHOD_GET_ROOT_URL = null;
  private static Method VFS_METHOD_GET_ROOT_URI = null;

  private static Method VIRTUAL_FILE_METHOD_EXISTS = null;
  private static Method VIRTUAL_FILE_METHOD_GET_INPUT_STREAM;
  private static Method VIRTUAL_FILE_METHOD_GET_SIZE;
  private static Method VIRTUAL_FILE_METHOD_GET_LAST_MODIFIED;
  private static Method VIRTUAL_FILE_METHOD_TO_URL;
  private static Method VIRTUAL_FILE_METHOD_TO_URI;
  private static Method VIRTUAL_FILE_METHOD_GET_NAME;
  private static Method VIRTUAL_FILE_METHOD_GET_PATH_NAME;
  private static Method VIRTUAL_FILE_METHOD_GET_CHILD;

  protected static Class<?> VIRTUAL_FILE_VISITOR_INTERFACE;
  protected static Method VIRTUAL_FILE_METHOD_VISIT;

  private static Method VFS_UTILS_METHOD_IS_NESTED_FILE = null;
  private static Method VFS_UTILS_METHOD_GET_COMPATIBLE_URI = null;
  private static Field VISITOR_ATTRIBUTES_FIELD_RECURSE = null;
  private static Method GET_PHYSICAL_FILE = null;

  static {
    ClassLoader loader = VfsUtils.class.getClassLoader();
    String pkg;
    Class<?> vfsClass;

    // check for JBoss 6
    try {
      vfsClass = loader.loadClass(VFS3_PKG + VFS_NAME);
      version = VFS_VER.V3;
      pkg = VFS3_PKG;

      if (logger.isDebugEnabled()) {
        logger.debug("JBoss VFS packages for JBoss AS 6 found");
      }
    }
    catch (ClassNotFoundException ex) {
      // fallback to JBoss 5
      if (logger.isDebugEnabled())
        logger.debug("JBoss VFS packages for JBoss AS 6 not found; falling back to JBoss AS 5 packages");
      try {
        vfsClass = loader.loadClass(VFS2_PKG + VFS_NAME);

        version = VFS_VER.V2;
        pkg = VFS2_PKG;

        if (logger.isDebugEnabled())
          logger.debug("JBoss VFS packages for JBoss AS 5 found");
      }
      catch (ClassNotFoundException ex2) {
        logger.error("JBoss VFS packages (for both JBoss AS 5 and 6) were not found - JBoss VFS support disabled");
        throw new IllegalStateException("Cannot detect JBoss VFS packages", ex2);
      }
    }

    // cache reflective information
    try {
      String methodName = (VFS_VER.V3.equals(version) ? "getChild" : "getRoot");

      VFS_METHOD_GET_ROOT_URL = ReflectionUtils.findMethod(vfsClass, methodName, URL.class);
      VFS_METHOD_GET_ROOT_URI = ReflectionUtils.findMethod(vfsClass, methodName, URI.class);

      Class<?> virtualFile = loader.loadClass(pkg + "VirtualFile");

      VIRTUAL_FILE_METHOD_EXISTS = ReflectionUtils.findMethod(virtualFile, "exists");
      VIRTUAL_FILE_METHOD_GET_INPUT_STREAM = ReflectionUtils.findMethod(virtualFile, "openStream");
      VIRTUAL_FILE_METHOD_GET_SIZE = ReflectionUtils.findMethod(virtualFile, "getSize");
      VIRTUAL_FILE_METHOD_GET_LAST_MODIFIED = ReflectionUtils.findMethod(virtualFile, "getLastModified");
      VIRTUAL_FILE_METHOD_TO_URI = ReflectionUtils.findMethod(virtualFile, "toURI");
      VIRTUAL_FILE_METHOD_TO_URL = ReflectionUtils.findMethod(virtualFile, "toURL");
      VIRTUAL_FILE_METHOD_GET_NAME = ReflectionUtils.findMethod(virtualFile, "getName");
      VIRTUAL_FILE_METHOD_GET_PATH_NAME = ReflectionUtils.findMethod(virtualFile, "getPathName");
      GET_PHYSICAL_FILE = ReflectionUtils.findMethod(virtualFile, "getPhysicalFile");

      methodName = (VFS_VER.V3.equals(version) ? "getChild" : "findChild");

      VIRTUAL_FILE_METHOD_GET_CHILD = ReflectionUtils.findMethod(virtualFile, methodName, String.class);

      Class<?> utilsClass = loader.loadClass(pkg + "VFSUtils");

      VFS_UTILS_METHOD_GET_COMPATIBLE_URI = ReflectionUtils.findMethod(utilsClass, "getCompatibleURI",
          virtualFile);
      VFS_UTILS_METHOD_IS_NESTED_FILE = ReflectionUtils.findMethod(utilsClass, "isNestedFile", virtualFile);

      VIRTUAL_FILE_VISITOR_INTERFACE = loader.loadClass(pkg + "VirtualFileVisitor");
      VIRTUAL_FILE_METHOD_VISIT = ReflectionUtils.findMethod(virtualFile, "visit", VIRTUAL_FILE_VISITOR_INTERFACE);

      Class<?> visitorAttributesClass = loader.loadClass(pkg + "VisitorAttributes");
      VISITOR_ATTRIBUTES_FIELD_RECURSE = ReflectionUtils.findField(visitorAttributesClass, "RECURSE");
    }
    catch (ClassNotFoundException ex) {
      throw new IllegalStateException("Could not detect the JBoss VFS infrastructure", ex);
    }
  }

  protected static Object invokeVfsMethod(Method method, Object target, Object... args) throws IOException {
    try {
      return method.invoke(target, args);
    }
    catch (InvocationTargetException ex) {
      Throwable targetEx = ex.getTargetException();
      if (targetEx instanceof IOException) {
        throw (IOException) targetEx;
      }
      ReflectionUtils.handleInvocationTargetException(ex);
    }
    catch (Exception ex) {
      ReflectionUtils.handleReflectionException(ex);
    }

    throw new IllegalStateException("Invalid code path reached");
  }

  static boolean exists(Object vfsResource) {
    try {
      return (Boolean) invokeVfsMethod(VIRTUAL_FILE_METHOD_EXISTS, vfsResource);
    }
    catch (IOException ex) {
      return false;
    }
  }

  static boolean isReadable(Object vfsResource) {
    try {
      return ((Long) invokeVfsMethod(VIRTUAL_FILE_METHOD_GET_SIZE, vfsResource) > 0);
    }
    catch (IOException ex) {
      return false;
    }
  }

  static long getSize(Object vfsResource) throws IOException {
    return (Long) invokeVfsMethod(VIRTUAL_FILE_METHOD_GET_SIZE, vfsResource);
  }

  static long getLastModified(Object vfsResource) throws IOException {
    return (Long) invokeVfsMethod(VIRTUAL_FILE_METHOD_GET_LAST_MODIFIED, vfsResource);
  }

  static InputStream getInputStream(Object vfsResource) throws IOException {
    return (InputStream) invokeVfsMethod(VIRTUAL_FILE_METHOD_GET_INPUT_STREAM, vfsResource);
  }

  static URL getURL(Object vfsResource) throws IOException {
    return (URL) invokeVfsMethod(VIRTUAL_FILE_METHOD_TO_URL, vfsResource);
  }

  static URI getURI(Object vfsResource) throws IOException {
    return (URI) invokeVfsMethod(VIRTUAL_FILE_METHOD_TO_URI, vfsResource);
  }

  static String getName(Object vfsResource) {
    try {
      return (String) invokeVfsMethod(VIRTUAL_FILE_METHOD_GET_NAME, vfsResource);
    }
    catch (IOException ex) {
      throw new IllegalStateException("Cannot get resource name", ex);
    }
  }

  static Object getRelative(URL url) throws IOException {
    return invokeVfsMethod(VFS_METHOD_GET_ROOT_URL, null, url);
  }

  static Object getChild(Object vfsResource, String path) throws IOException {
    return invokeVfsMethod(VIRTUAL_FILE_METHOD_GET_CHILD, vfsResource, path);
  }

  static File getFile(Object vfsResource) throws IOException {
    if (VFS_VER.V2.equals(version)) {
      if ((Boolean) invokeVfsMethod(VFS_UTILS_METHOD_IS_NESTED_FILE, null, vfsResource)) {
        throw new IOException("File resolution not supported for nested resource: " + vfsResource);
      }
      try {
        return new File((URI) invokeVfsMethod(VFS_UTILS_METHOD_GET_COMPATIBLE_URI, null, vfsResource));
      }
      catch (Exception ex) {
        throw new NestedIOException("Failed to obtain File reference for " + vfsResource, ex);
      }
    }
    else {
      return (File) invokeVfsMethod(GET_PHYSICAL_FILE, vfsResource);
    }
  }

  static Object getRoot(URI url) throws IOException {
    return invokeVfsMethod(VFS_METHOD_GET_ROOT_URI, null, url);
  }

  // protected methods used by the support sub-package

  protected static Object getRoot(URL url) throws IOException {
    return invokeVfsMethod(VFS_METHOD_GET_ROOT_URL, null, url);
  }

  protected static Object doGetVisitorAttribute() {
    return ReflectionUtils.getField(VISITOR_ATTRIBUTES_FIELD_RECURSE, null);
  }

  protected static String doGetPath(Object resource) {
    return (String) ReflectionUtils.invokeMethod(VIRTUAL_FILE_METHOD_GET_PATH_NAME, resource);
  }
}
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