Allow customizing the native library installation

src/main/java/net/lostluma/battery/api/util/LibraryUtil.java

@@ -0,0 +1,29 @@
+package net.lostluma.battery.api.util;
+
+import net.lostluma.battery.impl.util.NativeUtil;
+
+import java.nio.file.Path;
+
+/**
+ * Optional utilities to customize library installation.
+ */
+public class LibraryUtil {
+    /**
+     * Customize the directory for storing the dynamic library.
+     * By default, this is a subfolder in the user's cache directory.
+     *
+     * @param path the new cache directory
+     */
+    public static void setCacheDir(Path path) {
+        NativeUtil.setCacheDir(path);
+    }
+
+    /**
+     * Customize whether the dynamic library may be automatically downloaded.
+     *
+     * @param value whether to allow automatic library downloading. Defaults to true.
+     */
+    public static void setAllowDownloads(boolean value) {
+        NativeUtil.setAllowDownloads(value);
+    }
+}

src/main/java/net/lostluma/battery/impl/Constants.java

@@ -10,7 +10,7 @@ public final class Constants {
     public static final String VERSION = "1.0.0";
     public static final String NATIVES = "1.0.0";
 
-    public static Path CACHE_DIR = getCacheDir();
+    public static final Path CACHE_DIR = getCacheDir();
 
     private static String getUserHome() {
         return System.getProperty("user.home");

src/main/java/net/lostluma/battery/impl/ManagerImpl.java

@@ -3,7 +3,7 @@
 import net.lostluma.battery.api.Battery;
 import net.lostluma.battery.api.Manager;
 import net.lostluma.battery.api.exception.LibraryLoadError;
-import net.lostluma.battery.impl.util.LibraryUtil;
+import net.lostluma.battery.impl.util.NativeUtil;
 import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 
@@ -27,7 +27,7 @@ public final class ManagerImpl implements Manager {
     private final Map<PhantomReference<?>, Long> references;
 
     public ManagerImpl() throws IOException, LibraryLoadError {
-        LibraryUtil.load();
+        NativeUtil.load();
 
         this.ptr = create();
         this.active = true;

src/main/java/net/lostluma/battery/impl/util/LibraryUtil.java → src/main/java/net/lostluma/battery/impl/util/NativeUtil.java

@@ -12,7 +12,10 @@
 import java.util.Properties;
 
 @ApiStatus.Internal
-public class LibraryUtil {
+public class NativeUtil {
+    private static Path cacheDir = null;
+    private static boolean download = true;
+
     private static boolean isLoaded = false;
     private static final String BASE_URL = "https://files.lostluma.net/battery-jni/" + Constants.NATIVES + "/";
 
@@ -29,10 +32,18 @@ public static void load() throws LibraryLoadError {
         }
     }
 
+    public static void setCacheDir(Path path) {
+        cacheDir = path;
+    }
+
+    public static void setAllowDownloads(boolean value) {
+        download = value;
+    }
+
     private static void load0() throws IOException, LibraryLoadError{
         Properties properties = new Properties();
 
-        try (InputStream stream = LibraryUtil.class.getResourceAsStream("/natives.properties")) {
+        try (InputStream stream = NativeUtil.class.getResourceAsStream("/natives.properties")) {
             if (stream == null) {
                 throw new LibraryLoadError("Failed to read native library info.");
             }
@@ -49,9 +60,15 @@ private static void load0() throws IOException, LibraryLoadError{
         String name = properties.getProperty(base + ".name");
         String hash = properties.getProperty(base + ".hash");
 
-        Path path = Constants.CACHE_DIR.resolve(name);
+        Path path;
 
-        if (!isLibraryValid(path, hash)) {
+        if (cacheDir != null) {
+            path = cacheDir.resolve(name);
+        } else {
+            path = Constants.CACHE_DIR.resolve(name);
+        }
+
+        if (download && !isLibraryValid(path, hash)) {
             Files.createDirectories(Constants.CACHE_DIR);
             HttpUtil.download(new URL(BASE_URL + name), path);
         }