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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements.  See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache License, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License.  You may obtain a copy of the License at
    8    *
    9    *     http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the License for the specific language governing permissions and
    15   * limitations under the License.
    16   */
    17  package org.apache.commons.scxml.env.servlet;
    18
    19  import javax.servlet.ServletContext;
    20
    21  import org.apache.commons.scxml.PathResolver;
    22
    23  /***
    24   * A wrapper around ServletContext that implements PathResolver.
    25   *
    26   * @see org.apache.commons.scxml.PathResolver
    27   */
    28  public class ServletContextResolver implements PathResolver {
    29
    30      /*** Cannot accept a null ServletContext, it will just throw
    31       *  NullPointerException down the road. */
    32      private static final String ERR_SERVLET_CTX_NULL =
    33          "ServletContextResolver cannot be instantiated with a null"
    34          + " ServletContext";
    35
    36      /*** The SevletContext we will use to resolve paths. */
    37      private ServletContext ctx = null;
    38
    39      /***
    40       * Constructor.
    41       *
    42       * @param ctx The ServletContext instance for this web application.
    43       */
    44      public ServletContextResolver(final ServletContext ctx) {
    45          if (ctx == null) {
    46              throw new IllegalArgumentException(ERR_SERVLET_CTX_NULL);
    47          }
    48          this.ctx = ctx;
    49      }
    50
    51      /***
    52       * Delegates to the underlying ServletContext's getRealPath(String).
    53       *
    54       * @param ctxPath context sensitive path, can be a relative URL
    55       * @return resolved path (an absolute URL) or <code>null</code>
    56       * @see org.apache.commons.scxml.PathResolver#resolvePath(java.lang.String)
    57       */
    58      public String resolvePath(final String ctxPath) {
    59          return ctx.getRealPath(ctxPath);
    60      }
    61
    62      /***
    63       * Retrieve the PathResolver rooted at the given path.
    64       *
    65       * @param ctxPath context sensitive path, can be a relative URL
    66       * @return returns a new resolver rooted at ctxPath
    67       * @see org.apache.commons.scxml.PathResolver#getResolver(java.lang.String)
    68       */
    69      public PathResolver getResolver(final String ctxPath) {
    70          return this;
    71      }
    72
    73  }
    74