UPDATE

build.gradle

 apply plugin: 'com.android.library'
 
 android {
-    compileSdkVersion 26
-    buildToolsVersion '27.0.3'
+    compileSdkVersion rootProject.ext.compileSdkVersion
+    buildToolsVersion rootProject.ext.buildToolsVersion
 
     defaultConfig {
-        minSdkVersion 16
-        targetSdkVersion 26
-        versionCode 1
-        versionName "1.0"
+        minSdkVersion rootProject.ext.minSdkVersion
+        targetSdkVersion rootProject.ext.targetSdkVersion
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
 
         ndk {
@@ -37,9 +35,9 @@ dependencies {
     androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
 
     //support包
-    api "com.android.support:appcompat-v7:26.1.0"
-    api "com.android.support:support-v4:26.1.0"
-    api "com.android.support:recyclerview-v7:26.1.0"
+    api "com.android.support:appcompat-v7:$rootProject.ext.supportLibraryVersion"
+    api "com.android.support:support-v4:$rootProject.ext.supportLibraryVersion"
+    api "com.android.support:recyclerview-v7:$rootProject.ext.supportLibraryVersion"
 
     //QMUI
     api 'com.qmuiteam:qmui:1.1.3'