diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index f28e8a290..63ce63306 100755
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -32,10 +32,6 @@
         android:name="android.permission.WRITE_EXTERNAL_STORAGE"
         android:maxSdkVersion="28" />
 
-    <uses-feature
-        android:glEsVersion="0x00020000"
-        android:required="true" />
-
     <application
         android:name="com.hippo.ehviewer.EhApplication"
         android:allowBackup="true"
diff --git a/app/src/main/java/com/hippo/drawable/BatteryDrawable.java b/app/src/main/java/com/hippo/drawable/BatteryDrawable.java
deleted file mode 100644
index 557edb171..000000000
--- a/app/src/main/java/com/hippo/drawable/BatteryDrawable.java
+++ /dev/null
@@ -1,176 +0,0 @@
-/*
- * Copyright (C) 2014 Hippo Seven
- *
- * 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 com.hippo.drawable;
-
-import android.graphics.Canvas;
-import android.graphics.Color;
-import android.graphics.ColorFilter;
-import android.graphics.Paint;
-import android.graphics.PixelFormat;
-import android.graphics.Rect;
-import android.graphics.drawable.Drawable;
-
-import com.hippo.yorozuya.MathUtils;
-
-public class BatteryDrawable extends Drawable {
-
-    public static final int WARN_LIMIT = 15;
-    @SuppressWarnings("unused")
-    private static final String TAG = BatteryDrawable.class.getSimpleName();
-    private final Paint mPaint;
-    private final Rect mTopRect;
-    private final Rect mBottomRect;
-    private final Rect mRightRect;
-    private final Rect mHeadRect;
-    private final Rect mElectRect;
-    private int mColor = Color.WHITE;
-    private int mWarningColor = Color.RED;
-    private int mElect = -1;
-    private int mStart;
-    private int mStop;
-
-    public BatteryDrawable() {
-        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.DITHER_FLAG);
-        mPaint.setStyle(Paint.Style.FILL);
-
-        mTopRect = new Rect();
-        mBottomRect = new Rect();
-        mRightRect = new Rect();
-        mHeadRect = new Rect();
-        mElectRect = new Rect();
-        updatePaint();
-    }
-
-    @Override
-    @SuppressWarnings("SuspiciousNameCombination")
-    protected void onBoundsChange(Rect bounds) {
-        int width = bounds.width();
-        int height = bounds.height();
-        int strokeWidth = (int) (Math.sqrt(width * width + height * height) * 0.06f);
-        int turn1 = width * 6 / 7;
-        int turn2 = height / 3;
-        int secBottom = height - strokeWidth;
-        mStart = strokeWidth;
-        mStop = turn1 - strokeWidth;
-
-        mTopRect.set(0, 0, turn1, strokeWidth);
-        mBottomRect.set(0, secBottom, turn1, height);
-        mRightRect.set(turn1 - strokeWidth, strokeWidth, turn1, secBottom);
-        mHeadRect.set(turn1, turn2, width, height - turn2);
-        mElectRect.set(0, strokeWidth, mStop, secBottom);
-    }
-
-    /**
-     * How to draw:<br>
-     * |------------------------------|<br>
-     * |\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\|<br>
-     * |------------------------------|---|<br>
-     * |/////////////////|         |//|\\\|<br>
-     * |/////////////////|         |//|\\\|<br>
-     * |------------------------------|---|<br>
-     * |\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\|<br>
-     * |------------------------------|
-     */
-    @Override
-    public void draw(Canvas canvas) {
-        if (mElect == -1) {
-            return;
-        }
-
-        mElectRect.right = MathUtils.lerp(mStart, mStop, mElect / 100.0f);
-
-        canvas.drawRect(mTopRect, mPaint);
-        canvas.drawRect(mBottomRect, mPaint);
-        canvas.drawRect(mRightRect, mPaint);
-        canvas.drawRect(mHeadRect, mPaint);
-        canvas.drawRect(mElectRect, mPaint);
-    }
-
-    private boolean isWarn() {
-        return mElect <= WARN_LIMIT;
-    }
-
-    public void setColor(int color) {
-        if (mColor == color) {
-            return;
-        }
-
-        mColor = color;
-        if (!isWarn()) {
-            mPaint.setColor(mColor);
-            invalidateSelf();
-        }
-    }
-
-    public void setWarningColor(int color) {
-        if (mWarningColor == color) {
-            return;
-        }
-
-        mWarningColor = color;
-        if (isWarn()) {
-            mPaint.setColor(mWarningColor);
-            invalidateSelf();
-        }
-    }
-
-    public void setElect(int elect) {
-        if (mElect == elect) {
-            return;
-        }
-
-        mElect = elect;
-        updatePaint();
-    }
-
-    public void setElect(int elect, boolean warn) {
-        if (mElect == elect) {
-            return;
-        }
-
-        mElect = elect;
-        updatePaint(warn);
-    }
-
-    private void updatePaint() {
-        updatePaint(isWarn());
-    }
-
-    private void updatePaint(boolean warn) {
-        if (warn) {
-            mPaint.setColor(mWarningColor);
-        } else {
-            mPaint.setColor(mColor);
-        }
-        invalidateSelf();
-    }
-
-    @Override
-    public void setAlpha(int alpha) {
-        mPaint.setAlpha(alpha);
-    }
-
-    @Override
-    public void setColorFilter(ColorFilter cf) {
-        mPaint.setColorFilter(cf);
-    }
-
-    @Override
-    public int getOpacity() {
-        return PixelFormat.TRANSLUCENT;
-    }
-}
diff --git a/app/src/main/java/com/hippo/ehviewer/EhApplication.kt b/app/src/main/java/com/hippo/ehviewer/EhApplication.kt
index f648e7078..6c0c0fac7 100644
--- a/app/src/main/java/com/hippo/ehviewer/EhApplication.kt
+++ b/app/src/main/java/com/hippo/ehviewer/EhApplication.kt
@@ -78,7 +78,6 @@ class EhApplication : SceneApplication(), DefaultLifecycleObserver, ImageLoaderF
     private val mIdGenerator = IntIdGenerator()
     private val mGlobalStuffMap = HashMap<Int, Any>()
     private val mActivityList = ArrayList<Activity>()
-    private var initialized = false
     val topActivity: EhActivity?
         get() = if (mActivityList.isNotEmpty()) {
             mActivityList[mActivityList.size - 1] as EhActivity
@@ -149,7 +148,6 @@ class EhApplication : SceneApplication(), DefaultLifecycleObserver, ImageLoaderF
             theDawnOfNewDay()
         }
         mIdGenerator.setNextId(Settings.getInt(KEY_GLOBAL_STUFF_NEXT_ID, 0))
-        initialized = true
     }
 
     private suspend fun theDawnOfNewDay() {
@@ -298,7 +296,7 @@ class EhApplication : SceneApplication(), DefaultLifecycleObserver, ImageLoaderF
             val builder = OkHttpClient.Builder()
                 .cookieJar(ehCookieStore)
                 .cache(Cache(File(application.cacheDir, "http_cache"), 50L * 1024L * 1024L))
-                .dns(EhDns())
+                .dns(EhDns)
                 .proxySelector(ehProxySelector)
 
             if (Settings.getDF()) {
@@ -317,10 +315,10 @@ class EhApplication : SceneApplication(), DefaultLifecycleObserver, ImageLoaderF
                     trustManager = trustManagers[0] as X509TrustManager
                 } catch (e: Exception) {
                     e.printStackTrace()
-                    trustManager = EhX509TrustManager()
+                    trustManager = EhX509TrustManager
                 }
 
-                builder.sslSocketFactory(EhSSLSocketFactory(), trustManager)
+                builder.sslSocketFactory(EhSSLSocketFactory, trustManager)
                 builder.proxy(Proxy.NO_PROXY)
             }
             builder.build()
diff --git a/app/src/main/java/com/hippo/ehviewer/client/EhDns.kt b/app/src/main/java/com/hippo/ehviewer/client/EhDns.kt
index c90684a1b..7469a11c3 100644
--- a/app/src/main/java/com/hippo/ehviewer/client/EhDns.kt
+++ b/app/src/main/java/com/hippo/ehviewer/client/EhDns.kt
@@ -22,7 +22,7 @@ import okhttp3.Dns
 import java.net.InetAddress
 import java.net.UnknownHostException
 
-class EhDns : Dns {
+object EhDns : Dns {
     private val hosts = EhApplication.hosts
     private val builtInHosts: MutableMap<String, List<InetAddress>> = mutableMapOf()
 
diff --git a/app/src/main/java/com/hippo/ehviewer/client/EhSSLSocketFactory.kt b/app/src/main/java/com/hippo/ehviewer/client/EhSSLSocketFactory.kt
index d2ec934e6..735aac29c 100644
--- a/app/src/main/java/com/hippo/ehviewer/client/EhSSLSocketFactory.kt
+++ b/app/src/main/java/com/hippo/ehviewer/client/EhSSLSocketFactory.kt
@@ -23,7 +23,7 @@ import java.net.Socket
 import javax.net.ssl.SSLSocket
 import javax.net.ssl.SSLSocketFactory
 
-class EhSSLSocketFactory : SSLSocketFactory() {
+object EhSSLSocketFactory : SSLSocketFactory() {
     private val sslSocketFactory = getDefault() as SSLSocketFactory
     override fun getDefaultCipherSuites(): Array<String> {
         return sslSocketFactory.defaultCipherSuites
diff --git a/app/src/main/java/com/hippo/ehviewer/client/EhX509TrustManager.kt b/app/src/main/java/com/hippo/ehviewer/client/EhX509TrustManager.kt
index af7b1385e..6522b5bc7 100644
--- a/app/src/main/java/com/hippo/ehviewer/client/EhX509TrustManager.kt
+++ b/app/src/main/java/com/hippo/ehviewer/client/EhX509TrustManager.kt
@@ -22,7 +22,7 @@ import java.security.cert.X509Certificate
 import javax.net.ssl.X509TrustManager
 
 @SuppressLint("CustomX509TrustManager")
-class EhX509TrustManager : X509TrustManager {
+object EhX509TrustManager : X509TrustManager {
     @SuppressLint("TrustAllX509TrustManager")
     override fun checkClientTrusted(chain: Array<X509Certificate>, authType: String) {
     }