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java/org/apache/tomcat/util/file/ConfigFileLoader.java

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+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one or more
+ *  contributor license agreements.  See the NOTICE file distributed with
+ *  this work for additional information regarding copyright ownership.
+ *  The ASF licenses this file to You 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.apache.tomcat.util.file;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URI;
+import java.net.URL;
+
+import org.apache.tomcat.util.res.StringManager;
+
+/**
+ * This class is used to obtain {@link InputStream}s for configuration files
+ * from a given location String. This allows greater flexibility than these
+ * files having to be loaded directly from a file system.
+ */
+public class ConfigFileLoader {
+
+    private static final StringManager sm = StringManager.getManager(ConfigFileLoader.class
+            .getPackage().getName());
+
+    private static final File CATALINA_BASE_FILE;
+    private static final URI CATALINA_BASE_URI;
+
+    static {
+        String catalinaBase = System.getProperty("catalina.base");
+        if (catalinaBase != null) {
+            CATALINA_BASE_FILE = new File(catalinaBase);
+            CATALINA_BASE_URI = CATALINA_BASE_FILE.toURI();
+        } else {
+            CATALINA_BASE_FILE = null;
+            CATALINA_BASE_URI = null;
+        }
+    }
+
+    private ConfigFileLoader() {
+        // Utility class. Hide the default constructor.
+    }
+
+
+    /**
+     * Load the resource from the specified location.
+     *
+     * @param location The location for the resource of interest. The location
+     *                 may be a URL or a file path. Relative paths will be
+     *                 resolved against CATALINA_BASE.
+     *
+     * @return The InputStream for the given resource. The caller is responsible
+     *         for closing this stream when it is no longer used.
+     *
+     * @throws IOException If an InputStream cannot be created using the
+     *                     provided location
+     */
+    public static InputStream getInputStream(String location) throws IOException {
+        // Location was originally always a file before URI support was added so
+        // try file first.
+
+        File f = new File(location);
+        if (!f.isAbsolute()) {
+            f = new File(CATALINA_BASE_FILE, location);
+        }
+        if (f.isFile()) {
+            return new FileInputStream(f);
+        }
+
+        // File didn't work so try URI.
+        URI uri = getURI(location);
+
+        // Obtain the input stream we need
+        try {
+            URL url = uri.toURL();
+            return url.openConnection().getInputStream();
+        } catch (IllegalArgumentException e) {
+            throw new IOException(sm.getString("configFileLoader.cannotObtainURL", location), e);
+        }
+    }
+
+
+    public static URI getURI(String location) {
+        // Using resolve() enables the code to handle relative paths that did
+        // not point to a file
+        URI uri;
+        if (CATALINA_BASE_URI != null) {
+            uri = CATALINA_BASE_URI.resolve(location);
+        } else {
+            uri = URI.create(location);
+        }
+        return uri;
+    }
+}