content: /*
   * Copyright 2002-2021 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
   *
   *      https://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 com.alibaba.nacos.common.packagescan.resource;
  
  import com.alibaba.nacos.common.packagescan.util.AbstractObjectUtils;
  import com.alibaba.nacos.common.packagescan.util.AbstractAssert;
  import com.alibaba.nacos.common.utils.ClassUtils;
  import com.alibaba.nacos.common.utils.StringUtils;
  
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.io.InputStream;
  import java.net.URL;
  
  /**
   * Copy from https://github.com/spring-projects/spring-framework.git, with less modifications
   * {@link Resource} implementation for class path resources. Uses either a
   * given {@link ClassLoader} or a given {@link Class} for loading resources.
   *
   * <p>Supports resolution as {@code java.io.File} if the class path
   * resource resides in the file system, but not for resources in a JAR.
   * Always supports resolution as URL.
   *
   * @author Juergen Hoeller
   * @author Sam Brannen
   * @see ClassLoader#getResourceAsStream(String)
   * @see Class#getResourceAsStream(String)
   * @since 28.12.2003
   */
  public class ClassPathResource extends AbstractFileResolvingResource {
  
      private final String path;
  
      private ClassLoader classLoader;
  
      private Class<?> clazz;
  
      /**
       * Create a new {@code ClassPathResource} for {@code ClassLoader} usage.
       * A leading slash will be removed, as the ClassLoader resource access
       * methods will not accept it.
       *
       * <p>The thread context class loader will be used for
       * loading the resource.
       *
       * @param path the absolute path within the class path
       * @see ClassLoader#getResourceAsStream(String)
       * @see ClassUtils#getDefaultClassLoader()
       */
      public ClassPathResource(String path) {
          this(path, (ClassLoader) null);
      }
  
      /**
       * Create a new {@code ClassPathResource} for {@code ClassLoader} usage.
       * A leading slash will be removed, as the ClassLoader resource access
       * methods will not accept it.
       *
       * @param path        the absolute path within the classpath
       * @param classLoader the class loader to load the resource with,
       *                    or {@code null} for the thread context class loader
       * @see ClassLoader#getResourceAsStream(String)
       */
      public ClassPathResource(String path, ClassLoader classLoader) {
          AbstractAssert.notNull(path, "Path must not be null");
          String pathToUse = StringUtils.cleanPath(path);
          if (pathToUse.startsWith("/")) {
              pathToUse = pathToUse.substring(1);
          }
          this.path = pathToUse;
          this.classLoader = (classLoader != null ? classLoader : ClassUtils.getDefaultClassLoader());
      }
  
      /**
       * Create a new {@code ClassPathResource} for {@code Class} usage.
       * The path can be relative to the given class, or absolute within
       * the classpath via a leading slash.
       *
       * @param path  relative or absolute path within the class path
       * @param clazz the class to load resources with
       * @see Class#getResourceAsStream
       */
      public ClassPathResource(String path, Class<?> clazz) {
          AbstractAssert.notNull(path, "Path must not be null");
          this.path = StringUtils.cleanPath(path);
          this.clazz = clazz;
      }
  
      /**
       * Create a new {@code ClassPathResource} with optional {@code ClassLoader}
       * and {@code Class}. Only for internal usage.
       *
       * @param path        relative or absolute path within the classpath
       * @param classLoader the class loader to load the resource with, if any
       * @param clazz       the class to load resources with, if any
       * @deprecated as of 4.3.13, in favor of selective use of
       * {@link #ClassPathResource(String, ClassLoader)} vs {@link #ClassPathResource(String, Class)}
       */
      @Deprecated
      protected ClassPathResource(String path, ClassLoader classLoader, Class<?> clazz) {
          this.path = StringUtils.cleanPath(path);
          this.classLoader = classLoader;
          this.clazz = clazz;
      }
  
      /**
       * Return the path for this resource (as resource path within the class path).
       */
      public final String getPath() {
          return this.path;
      }
  
      /**
       * Return the ClassLoader that this resource will be obtained from.
       */
  
      public final ClassLoader getClassLoader() {
          return (this.clazz != null ? this.clazz.getClassLoader() : this.classLoader);
      }
  
  
      /**
       * This implementation checks for the resolution of a resource URL.
       *
       * @see ClassLoader#getResource(String)
       * @see Class#getResource(String)
       */
      @Override
      public boolean exists() {
          return (resolveUrl() != null);
      }
  
      /**
       * This implementation checks for the resolution of a resource URL upfront,
       * then proceeding with {@link AbstractFileResolvingResource}'s length check.
       *
       * @see ClassLoader#getResource(String)
       * @see Class#getResource(String)
       */
      @Override
      public boolean isReadable() {
          URL url = resolveUrl();
          return (url != null && checkReadable(url));
      }
  
      /**
       * Resolves a URL for the underlying class path resource.
       *
       * @return the resolved URL, or {@code null} if not resolvable
       */
  
      protected URL resolveUrl() {
          try {
              if (this.clazz != null) {
                  return this.clazz.getResource(this.path);
              } else if (this.classLoader != null) {
                  return this.classLoader.getResource(this.path);
              } else {
                  return ClassLoader.getSystemResource(this.path);
              }
          } catch (IllegalArgumentException ex) {
              // Should not happen according to the JDK's contract:
              // see https://github.com/openjdk/jdk/pull/2662
              return null;
          }
      }
  
      /**
       * This implementation opens an InputStream for the given class path resource.
       *
       * @see ClassLoader#getResourceAsStream(String)
       * @see Class#getResourceAsStream(String)
       */
      @Override
      public InputStream getInputStream() throws IOException {
          InputStream is;
          if (this.clazz != null) {
              is = this.clazz.getResourceAsStream(this.path);
          } else if (this.classLoader != null) {
              is = this.classLoader.getResourceAsStream(this.path);
          } else {
              is = ClassLoader.getSystemResourceAsStream(this.path);
          }
          if (is == null) {
              throw new FileNotFoundException(getDescription() + " cannot be opened because it does not exist");
          }
          return is;
      }
  
      /**
       * This implementation returns a URL for the underlying class path resource,
       * if available.
       *
       * @see ClassLoader#getResource(String)
       * @see Class#getResource(String)
       */
      @Override
      public URL getUrl() throws IOException {
          URL url = resolveUrl();
          if (url == null) {
              throw new FileNotFoundException(getDescription() + " cannot be resolved to URL because it does not exist");
          }
          return url;
      }
  
      /**
       * This implementation creates a ClassPathResource, applying the given path
       * relative to the path of the underlying resource of this descriptor.
       *
       * @see StringUtils#applyRelativePath(String, String)
       */
      @Override
      public Resource createRelative(String relativePath) {
          String pathToUse = StringUtils.applyRelativePath(this.path, relativePath);
          return (this.clazz != null ? new ClassPathResource(pathToUse, this.clazz) :
                  new ClassPathResource(pathToUse, this.classLoader));
      }
  
      /**
       * This implementation returns the name of the file that this class path
       * resource refers to.
       *
       * @see StringUtils#getFilename(String)
       */
      @Override
  
      public String getFilename() {
          return StringUtils.getFilename(this.path);
      }
  
      /**
       * This implementation returns a description that includes the class path location.
       */
      @Override
      public String getDescription() {
          StringBuilder builder = new StringBuilder("class path resource [");
          String pathToUse = this.path;
          if (this.clazz != null && !pathToUse.startsWith("/")) {
              builder.append(ClassUtils.classPackageAsResourcePath(this.clazz));
              builder.append('/');
          }
          if (pathToUse.startsWith("/")) {
              pathToUse = pathToUse.substring(1);
          }
          builder.append(pathToUse);
          builder.append(']');
          return builder.toString();
      }
  
  
      /**
       * This implementation compares the underlying class path locations.
       */
      @Override
      public boolean equals(Object other) {
          if (this == other) {
              return true;
          }
          if (!(other instanceof ClassPathResource)) {
              return false;
          }
          ClassPathResource otherRes = (ClassPathResource) other;
          return (this.path.equals(otherRes.path)
                  && AbstractObjectUtils.nullSafeEquals(this.classLoader, otherRes.classLoader)
                  && AbstractObjectUtils.nullSafeEquals(this.clazz, otherRes.clazz));
      }
  
      /**
       * This implementation returns the hash code of the underlying
       * class path location.
       */
      @Override
      public int hashCode() {
          return this.path.hashCode();
      }
  
  }
  