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From desruisse...@apache.org
Subject svn commit: r1489620 - /sis/branches/JDK7/storage/sis-netcdf/src/main/java/org/apache/sis/storage/netcdf/NetcdfStoreProvider.java
Date Tue, 04 Jun 2013 21:26:01 GMT
Author: desruisseaux
Date: Tue Jun  4 21:25:50 2013
New Revision: 1489620

URL: http://svn.apache.org/r1489620
Log:
First draft of NetcdfStoreProvider. Not yet completed: missing public API and test cases.

Added:
    sis/branches/JDK7/storage/sis-netcdf/src/main/java/org/apache/sis/storage/netcdf/NetcdfStoreProvider.java
  (with props)

Added: sis/branches/JDK7/storage/sis-netcdf/src/main/java/org/apache/sis/storage/netcdf/NetcdfStoreProvider.java
URL: http://svn.apache.org/viewvc/sis/branches/JDK7/storage/sis-netcdf/src/main/java/org/apache/sis/storage/netcdf/NetcdfStoreProvider.java?rev=1489620&view=auto
==============================================================================
--- sis/branches/JDK7/storage/sis-netcdf/src/main/java/org/apache/sis/storage/netcdf/NetcdfStoreProvider.java
(added)
+++ sis/branches/JDK7/storage/sis-netcdf/src/main/java/org/apache/sis/storage/netcdf/NetcdfStoreProvider.java
[UTF-8] Tue Jun  4 21:25:50 2013
@@ -0,0 +1,165 @@
+/*
+ * 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.sis.storage.netcdf;
+
+import java.io.IOException;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.UndeclaredThrowableException;
+import org.apache.sis.internal.netcdf.Decoder;
+import org.apache.sis.internal.netcdf.impl.ChannelDecoder;
+import org.apache.sis.internal.netcdf.ucar.DecoderWrapper;
+import org.apache.sis.internal.storage.ChannelDataInput;
+import org.apache.sis.internal.storage.WarningProducer;
+import org.apache.sis.storage.DataStoreConnection;
+import org.apache.sis.storage.DataStoreException;
+
+
+/**
+ * The provider of {@link NetcdfStore} instances. Given an {@link DataStoreConnection} input,
+ * this class tries to instantiate a {@code NetcdfStore} using the embedded NetCDF decoder.
+ * If the embedded decoder can not decode the given input and the UCAR library is reachable
+ * on the classpath, then this class tries to instantiate a {@code NetcdfStore} backed by
+ * the UCAR library.
+ *
+ * @author  Martin Desruisseaux (Geomatys)
+ * @since   0.3
+ * @version 0.3
+ * @module
+ */
+public class NetcdfStoreProvider {
+    /**
+     * The {@link ucar.nc2.NetcdfFile} class, or {@code null} if not found. An attempt to
load this class
+     * will be performed when first needed since the UCAR library is optional. If not found,
then this field
+     * will be assigned the {@link Void#TYPE} sentinel value, meaning "No UCAR library on
the classpath".
+     */
+    private static Class<?> netcdfFileClass;
+
+    /**
+     * If the {@link #netcdfFileClass} has been found, then the {@link DecoderWrapper} constructor
receiving
+     * in argument a UCAR {@code NetcdfFile} object. Otherwise {@code null}.
+     */
+    private static volatile Constructor<? extends Decoder> fromUCAR;
+
+    /**
+     * If the {@link #netcdfFileClass} has been found, then the {@link DecoderWrapper} constructor
receiving
+     * in argument the name of the NetCDF file as a {@link String} object. Otherwise {@code
null}.
+     */
+    private static volatile Constructor<? extends Decoder> fromFilename;
+
+    /**
+     * Creates a new provider.
+     */
+    public NetcdfStoreProvider() {
+    }
+
+    /**
+     * Creates a decoder for the given input.
+     *
+     * @param  sink       Where to send the warnings, or {@code null} if none.
+     * @param  connection Information about the input (file, input stream, <i>etc.</i>)
+     * @return The decoder for the given input.
+     * @throws IOException If an error occurred while opening the NetCDF file.
+     * @throws DataStoreException If a logical error (other than I/O) occurred.
+     */
+    static Decoder decoder(final WarningProducer sink, final DataStoreConnection connection)
+            throws IOException, DataStoreException
+    {
+        final ChannelDataInput input = connection.getStorageAs(ChannelDataInput.class);
+        if (input != null) try {
+            return new ChannelDecoder(sink, input);
+        } catch (DataStoreException e) {
+            final String path = connection.getStorageAs(String.class);
+            if (path != null) try {
+                return createByReflection(sink, path, false);
+            } catch (IOException | DataStoreException s) {
+                e.addSuppressed(s);
+            }
+            throw e;
+        }
+        return createByReflection(sink, connection, true);
+    }
+
+    /**
+     * Creates a new NetCDF decoder as a wrapper around the UCAR library. This decoder is
used only when we can
+     * not create our embedded NetCDF decoder. This method uses reflection for creating the
wrapper, in order
+     * to keep the UCAR dependency optional.
+     *
+     * @param  sink   Where to send the warnings, or {@code null} if none.
+     * @param  input  The NetCDF file object of filename string from which to read data.
+     * @param  isUCAR {@code true} if {@code input} is an instance of the UCAR {@link ucar.nc2.NetcdfFile}
object,
+     *                or {@code false} if it is the filename as a {@code String}.
+     * @return The {@link DecoderWrapper} instance for the given input.
+     * @throws IOException If an error occurred while opening the NetCDF file.
+     * @throws DataStoreException If a logical error (other than I/O) occurred.
+     */
+    private static Decoder createByReflection(final WarningProducer sink, final Object input,
final boolean isUCAR)
+            throws IOException, DataStoreException
+    {
+        /*
+         * Get the java.lang.Class that represent the ucar.nc2.NetcdfFile type. We do not
synchronize since it
+         * is not a big deal if Class.forName(…) is invoked twice. The Class.forName(…)
method performs itself
+         * the required synchronization for returning the same singleton Class instance.
+         */
+        if (netcdfFileClass == null) {
+            try {
+                netcdfFileClass = Class.forName("ucar.nc2.NetcdfFile");
+            } catch (ClassNotFoundException e) {
+                netcdfFileClass = Void.TYPE;
+                return null;
+            }
+            try {
+                final Class<? extends Decoder> wrapper =
+                        Class.forName("org.apache.sis.internal.netcdf.ucar.DecoderWrapper").asSubclass(Decoder.class);
+                final Class<?>[] parameterTypes = new Class<?>[] {WarningProducer.class,
netcdfFileClass};
+                fromUCAR = wrapper.getConstructor(parameterTypes);
+                parameterTypes[1] = String.class;
+                fromFilename = wrapper.getConstructor(parameterTypes);
+            } catch (ReflectiveOperationException e) {
+                throw new AssertionError(e); // Should never happen (shall be verified by
the JUnit tests).
+            }
+        }
+        /*
+         * Get the appropriate constructor for the isUCAR argument. This constructor will
be null
+         * if the above code failed to load the UCAR library. Otherwise, instantiate the
wrapper.
+         */
+        final Constructor<? extends Decoder> constructor;
+        final Class<?> expectedType;
+        if (isUCAR) {
+            constructor  = fromUCAR;
+            expectedType = netcdfFileClass;
+        } else {
+            constructor  = fromFilename;
+            expectedType = String.class;
+        }
+        if (constructor == null || !expectedType.isInstance(input)) {
+            return null;
+        }
+        try {
+            return constructor.newInstance(sink, input);
+        } catch (InvocationTargetException e) {
+            final Throwable cause = e.getCause();
+            if (cause instanceof IOException)        throw (IOException)        cause;
+            if (cause instanceof DataStoreException) throw (DataStoreException) cause;
+            if (cause instanceof RuntimeException)   throw (RuntimeException)   cause;
+            if (cause instanceof Error)              throw (Error)              cause;
+            throw new UndeclaredThrowableException(cause); // Should never happen actually.
+        } catch (ReflectiveOperationException e) {
+            throw new AssertionError(e); // Should never happen (shall be verified by the
JUnit tests).
+        }
+    }
+}

Propchange: sis/branches/JDK7/storage/sis-netcdf/src/main/java/org/apache/sis/storage/netcdf/NetcdfStoreProvider.java
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