Implemented a FlutterMethodCallHandler base class.

Author: artob

android/src/main/java/com/github/drydart/flutter_sqlcipher/FlutterMethodCallHandler.java

@@ -0,0 +1,78 @@
+/* This is free and unencumbered software released into the public domain. */
+
+package com.github.drydart.flutter_sqlcipher;
+
+import android.content.res.AssetFileDescriptor;
+import android.content.res.AssetManager;
+import android.graphics.Bitmap;
+import android.graphics.BitmapFactory;
+import io.flutter.plugin.common.MethodCall;
+import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
+import io.flutter.plugin.common.PluginRegistry.Registrar;
+import java.io.InputStream;
+import java.io.IOException;
+
+/** FlutterMethodCallHandler */
+@SuppressWarnings("unchecked")
+abstract class FlutterMethodCallHandler implements MethodCallHandler {
+  final Registrar registrar;
+
+  FlutterMethodCallHandler(final Registrar registrar) {
+    this.registrar = registrar;
+  }
+
+  AssetManager
+  getAssets() {
+    return registrar.context().getAssets();
+  }
+
+  AssetFileDescriptor
+  openAsset(final String assetName) throws IOException {
+    final String assetKey = registrar.lookupKeyForAsset(assetName);
+    return getAssets().openFd(assetKey);
+  }
+
+  Bitmap
+  loadBitmap(final String assetName) throws IOException {
+    return loadBitmap(assetName, null);
+  }
+
+  Bitmap
+  loadBitmap(final String assetName,
+             final BitmapFactory.Options options) throws IOException {
+    final InputStream stream = openAsset(assetName).createInputStream();
+    return BitmapFactory.decodeStream(stream, null, options);
+  }
+
+  static <T> T
+  getRequiredArgument(final MethodCall call,
+                      final String name) {
+    assert(call != null);
+    assert(name != null);
+
+    if (!call.hasArgument(name)) {
+      throw new AssertionError();
+    }
+    final T arg = call.argument(name);
+    if (arg == null) {
+      throw new AssertionError();
+    }
+    return arg;
+  }
+
+  static <T> T
+  getOptionalArgument(final MethodCall call,
+                      final String name) {
+    return getOptionalArgument(call, name, (T)null);
+  }
+
+  static <T> T
+  getOptionalArgument(final MethodCall call,
+                      final String name,
+                      final T defaultValue) {
+    assert(call != null);
+    assert(name != null);
+
+    return call.hasArgument(name) ? (T)call.argument(name) : defaultValue;
+  }
+}

android/src/main/java/com/github/drydart/flutter_sqlcipher/SQLCipherMethodHandler.java

@@ -10,13 +10,11 @@
 import net.sqlcipher.database.SQLiteDatabase;
 
 /** SQLCipherMethodHandler */
-class SQLCipherMethodHandler implements MethodCallHandler {
+class SQLCipherMethodHandler extends FlutterMethodCallHandler {
   static final String CHANNEL = "flutter_sqlcipher/SQLCipher";
 
-  final Registrar registrar;
-
   SQLCipherMethodHandler(final Registrar registrar) {
-    this.registrar = registrar;
+    super(registrar);
   }
 
   @Override

android/src/main/java/com/github/drydart/flutter_sqlcipher/SQLiteCursorMethodHandler.java

@@ -10,13 +10,11 @@
 import net.sqlcipher.database.SQLiteCursor;
 
 /** SQLiteCursorMethodHandler */
-class SQLiteCursorMethodHandler implements MethodCallHandler {
+class SQLiteCursorMethodHandler extends FlutterMethodCallHandler {
   static final String CHANNEL = "flutter_sqlcipher/SQLiteCursor";
 
-  final Registrar registrar;
-
   SQLiteCursorMethodHandler(final Registrar registrar) {
-    this.registrar = registrar;
+    super(registrar);
   }
 
   @Override

android/src/main/java/com/github/drydart/flutter_sqlcipher/SQLiteDatabaseMethodHandler.java

@@ -20,15 +20,14 @@
 
 /** SQLiteDatabaseMethodHandler */
 @SuppressWarnings("unchecked")
-class SQLiteDatabaseMethodHandler implements MethodCallHandler {
+class SQLiteDatabaseMethodHandler extends FlutterMethodCallHandler {
   static final String CHANNEL = "flutter_sqlcipher/SQLiteDatabase";
 
-  final Registrar registrar;
   final Map<Integer, SQLiteDatabase> databases = new HashMap<>();
   int databaseID;
 
   SQLiteDatabaseMethodHandler(final Registrar registrar) {
-    this.registrar = registrar;
+    super(registrar);
   }
 
   @Override
@@ -442,38 +441,6 @@ class SQLiteDatabaseMethodHandler implements MethodCallHandler {
     return this.databases.get(id);
   }
 
-  private static <T> T
-  getRequiredArgument(final MethodCall call,
-                      final String name) {
-    assert(call != null);
-    assert(name != null);
-
-    if (!call.hasArgument(name)) {
-      throw new AssertionError();
-    }
-    final T arg = call.argument(name);
-    if (arg == null) {
-      throw new AssertionError();
-    }
-    return arg;
-  }
-
-  private static <T> T
-  getOptionalArgument(final MethodCall call,
-                      final String name) {
-    return getOptionalArgument(call, name, (T)null);
-  }
-
-  private static <T> T
-  getOptionalArgument(final MethodCall call,
-                      final String name,
-                      final T defaultValue) {
-    assert(call != null);
-    assert(name != null);
-
-    return call.hasArgument(name) ? (T)call.argument(name) : defaultValue;
-  }
-
   private static ContentValues
   convertMapToContentValues(final Map<String, Object> input) {
     assert(input != null);

android/src/main/java/com/github/drydart/flutter_sqlcipher/SQLiteMethodHandler.java

@@ -10,13 +10,11 @@
 import net.sqlcipher.database.SQLiteDatabase;
 
 /** SQLiteMethodHandler */
-class SQLiteMethodHandler implements MethodCallHandler {
+class SQLiteMethodHandler extends FlutterMethodCallHandler {
   static final String CHANNEL = "flutter_sqlcipher/SQLite";
 
-  final Registrar registrar;
-
   SQLiteMethodHandler(final Registrar registrar) {
-    this.registrar = registrar;
+    super(registrar);
   }
 
   @Override