AppDataDirectory: Move from wallettemplate/.utils to core/.utils

This allows usage in both wallettemplate and tools and replaces
similar code in BlockFileLoader.java in core.
Requires minor back-port of Path.of() functionality from JDK11.

core/src/main/java/org/bitcoinj/utils/AppDataDirectory.java

@@ -14,16 +14,25 @@
  * limitations under the License.
  */
 
-package wallettemplate.utils;
+package org.bitcoinj.utils;
 
 import org.bitcoinj.core.Utils;
 
 import java.io.IOException;
+import java.nio.file.FileSystems;
 import java.nio.file.Files;
 import java.nio.file.Path;
 
 /**
  * Find/create App Data Directory in correct platform-specific location.
+ * This class is based on the conventions used in Bitcoin Core which
+ * uses the following locations:
+ * <dl>
+ *     <dt>Windows</dt><dd>{@code ${APPDATA}/.bitcoin}</dd>
+ *     <dt>macOS</dt><dd>{@code ${HOME}/Library/Application Support/Bitcoin}</dd>
+ *     <dt>Linux</dt><dd>{@code ${HOME}/.bitcoin}</dd>
+ * </dl>
+ * Note that {@code appName} is converted to lower-case on Windows and Linux/Unix.
  */
 public class AppDataDirectory {
 
@@ -45,19 +54,36 @@ public class AppDataDirectory {
         return applicationDataDirectory;
     }
 
-    private static Path getPath(String appName) {
+    /**
+     * Return the Path to the application data directory without making
+     * sure it exists or creating it. (No disk I/O)
+     *
+     * @param appName The name of the current application
+     * @return Path to the application data directory
+     */
+    public static Path getPath(String appName) {
         final Path applicationDataDirectory;
 
         if (Utils.isWindows()) {
-            applicationDataDirectory = Path.of(System.getenv("APPDATA"), appName.toLowerCase());
+            applicationDataDirectory = pathOf(System.getenv("APPDATA"), appName.toLowerCase());
         } else if (Utils.isMac()) {
-            applicationDataDirectory = Path.of(System.getProperty("user.home"),"Library/Application Support", appName);
+            applicationDataDirectory = pathOf(System.getProperty("user.home"),"Library/Application Support", appName);
         } else if (Utils.isLinux()) {
-            applicationDataDirectory = Path.of(System.getProperty("user.home"), "." + appName.toLowerCase());
+            applicationDataDirectory = pathOf(System.getProperty("user.home"), "." + appName.toLowerCase());
         } else {
             // Unknown, assume unix-like
-            applicationDataDirectory = Path.of(System.getProperty("user.home"), "." + appName.toLowerCase());
+            applicationDataDirectory = pathOf(System.getProperty("user.home"), "." + appName.toLowerCase());
         }
         return applicationDataDirectory;
     }
+
+    /**
+     * Create a {@code Path} by joining path strings. Same functionality as Path.of() in JDK 11+
+     * @param first A base path string
+     * @param additional additional components to add
+     * @return the joined {@code Path}
+     */
+    private static Path pathOf(String first, String... additional) {
+        return FileSystems.getDefault().getPath(first, additional);
+    }
 }

core/src/main/java/org/bitcoinj/utils/BlockFileLoader.java

@@ -71,16 +71,9 @@ public class BlockFileLoader implements Iterable<Block>, Iterator<Block> {
     }
 
     public static File defaultBlocksDir() {
-        final File defaultBlocksDir;
-        if (Utils.isWindows()) {
-            defaultBlocksDir = new File(System.getenv("APPDATA") + "\\.bitcoin\\blocks\\");
-        } else if (Utils.isMac()) {
-            defaultBlocksDir = new File(System.getProperty("user.home") + "/Library/Application Support/Bitcoin/blocks/");
-        } else if (Utils.isLinux()) {
-            defaultBlocksDir = new File(System.getProperty("user.home") + "/.bitcoin/blocks/");
-        } else {
-            throw new RuntimeException("Unsupported system");
-        }
+        File defaultBlocksDir = AppDataDirectory.getPath("Bitcoin").resolve("blocks").toFile();
+        if (!defaultBlocksDir.isDirectory())
+            throw new RuntimeException("Default blocks directory not found");
         return defaultBlocksDir;
     }
 

core/src/test/java/org/bitcoinj/utils/AppDataDirectoryTest.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2019 Michael Sean Gilligan
+ *
+ * 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 org.bitcoinj.utils;
+
+import org.bitcoinj.core.Utils;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Basic test of AppDataDirectory
+ */
+public class AppDataDirectoryTest {
+    private static final String HOMEDIR = System.getProperty("user.home");
+    private static final String WINAPPDATA = System.getenv("APPDATA");
+
+    @Test
+    public void worksOnCurrentPlatform() {
+        final String appName = "bitcoinj";
+        String path = AppDataDirectory.get(appName).toString();
+        if (Utils.isWindows()) {
+            assertEquals("Path wrong on Mac", winPath(appName), path);
+        } else if (Utils.isMac()) {
+            assertEquals("Path wrong on Mac",  macPath(appName), path);
+        } else if (Utils.isLinux()) {
+            assertEquals("Path wrong on Linux",  unixPath(appName), path);
+        } else {
+            assertEquals("Path wrong on unknown/default",  unixPath(appName), path);
+        }
+    }
+
+    @Test
+    public void worksOnCurrentPlatformForBitcoinCore() {
+        final String appName = "Bitcoin";
+        String path = AppDataDirectory.get(appName).toString();
+        if (Utils.isWindows()) {
+            assertEquals("Path wrong on Mac", winPath(appName), path);
+        } else if (Utils.isMac()) {
+            assertEquals("Path wrong on Mac",  macPath(appName), path);
+        } else if (Utils.isLinux()) {
+            assertEquals("Path wrong on Linux",  unixPath(appName), path);
+        } else {
+            assertEquals("Path wrong on unknown/default",  unixPath(appName), path);
+        }
+    }
+
+    private static String winPath(String appName) {
+        return WINAPPDATA + "\\." + appName.toLowerCase();
+    }
+
+    private static String macPath(String appName) {
+        return HOMEDIR + "/Library/Application Support/" + appName;
+    }
+
+    private static String unixPath(String appName) {
+        return HOMEDIR + "/." + appName.toLowerCase();
+    }
+}

wallettemplate/src/main/java/wallettemplate/Main.java

@@ -18,6 +18,7 @@ package wallettemplate;
 
 import com.google.common.util.concurrent.*;
 import javafx.scene.input.*;
+import org.bitcoinj.utils.AppDataDirectory;
 import org.bitcoinj.core.NetworkParameters;
 import org.bitcoinj.core.Utils;
 import org.bitcoinj.kits.WalletAppKit;
@@ -35,7 +36,6 @@ import javafx.scene.layout.Pane;
 import javafx.scene.layout.StackPane;
 import javafx.stage.Stage;
 import wallettemplate.controls.NotificationBarPane;
-import wallettemplate.utils.AppDataDirectory;
 import wallettemplate.utils.GuiUtils;
 import wallettemplate.utils.TextFieldValidator;