initialDbFile provisioning

Author: greenrobot

objectbox-java/src/main/java/io/objectbox/BoxStoreBuilder.java

@@ -16,7 +16,16 @@
 
 package io.objectbox;
 
+import org.greenrobot.essentials.io.IoUtils;
+
+import java.io.BufferedInputStream;
+import java.io.BufferedOutputStream;
 import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.InputStream;
+import java.io.OutputStream;
 import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.List;
@@ -26,6 +35,7 @@
 
 import io.objectbox.annotation.apihint.Experimental;
 import io.objectbox.annotation.apihint.Internal;
+import io.objectbox.exception.DbException;
 import io.objectbox.ideasonly.ModelUpdate;
 
 /**
@@ -80,6 +90,7 @@ public class BoxStoreBuilder {
     TxCallback failedReadTxAttemptCallback;
 
     final List<EntityInfo> entityInfoList = new ArrayList<>();
+    private Factory<InputStream> initialDbFileFactory;
 
     /** Not for application use. */
     public static BoxStoreBuilder createDebugWithoutModel() {
@@ -306,6 +317,22 @@ public BoxStoreBuilder failedReadTxAttemptCallback(TxCallback failedReadTxAttemp
         return this;
     }
 
+    @Experimental
+    public BoxStoreBuilder initialDbFile(final File initialDbFile) {
+        return initialDbFile(new Factory<InputStream>() {
+            @Override
+            public InputStream provide() throws FileNotFoundException {
+                return new FileInputStream(initialDbFile);
+            }
+        });
+    }
+
+    @Experimental
+    public BoxStoreBuilder initialDbFile(Factory<InputStream> initialDbFileFactory) {
+        this.initialDbFileFactory = initialDbFileFactory;
+        return this;
+    }
+
     /**
      * Builds a {@link BoxStore} using any given configuration.
      */
@@ -314,9 +341,35 @@ public BoxStore build() {
             name = dbName(name);
             directory = getDbDir(baseDirectory, name);
         }
+        checkProvisionInitialDbFile();
         return new BoxStore(this);
     }
 
+    private void checkProvisionInitialDbFile() {
+        if (initialDbFileFactory != null) {
+            String dataDir = BoxStore.getCanonicalPath(directory);
+            File file = new File(dataDir, "data.mdb");
+            if (!file.exists()) {
+                InputStream in = null;
+                OutputStream out = null;
+                try {
+                    in = initialDbFileFactory.provide();
+                    if (in == null) {
+                        throw new DbException("Factory did not provide a resource");
+                    }
+                    in = new BufferedInputStream(in);
+                    out = new BufferedOutputStream(new FileOutputStream(file));
+                    IoUtils.copyAllBytes(in, out);
+                } catch (Exception e) {
+                    throw new DbException("Could not provision initial data file", e);
+                } finally {
+                    IoUtils.safeClose(out);
+                    IoUtils.safeClose(in);
+                }
+            }
+        }
+    }
+
     static File getDbDir(@Nullable File baseDirectoryOrNull, @Nullable String nameOrNull) {
         String name = dbName(nameOrNull);
         if (baseDirectoryOrNull != null) {

objectbox-java/src/main/java/io/objectbox/Factory.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2017 ObjectBox Ltd. All rights reserved.
+ *
+ * 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 io.objectbox;
+
+import io.objectbox.annotation.apihint.Experimental;
+
+
+@Experimental
+/**
+ * Generic Factory that provides a resource on demand (if and when it is required).
+ */
+public interface Factory<T> {
+    T provide() throws Exception;
+}