diff --git a/build.gradle b/build.gradle
index 76f3d3a..7b8976e 100644
--- a/build.gradle
+++ b/build.gradle
@@ -2,7 +2,7 @@
 buildscript {
     repositories {
 		maven { url 'https://maven.aliyun.com/repository/google' }
-		maven { url 'https://maven.aliyun.com/nexus/content/groups/public' }
+		maven { url 'https://maven.aliyun.com/repository/central' }
 
 		google()
 		mavenCentral()
@@ -15,8 +15,7 @@ buildscript {
 allprojects {
     repositories {
 		maven { url 'https://maven.aliyun.com/repository/google' }
-		maven { url 'https://maven.aliyun.com/repository/jcenter' }
-		maven { url 'https://maven.aliyun.com/nexus/content/groups/public' }
+		maven { url 'https://maven.aliyun.com/repository/central' }
 
 		maven { url 'https://jitpack.io' }
 
diff --git a/demo/src/main/java/com/herohan/uvcdemo/EntryActivity.java b/demo/src/main/java/com/herohan/uvcdemo/EntryActivity.java
index 40e48ff..51c5924 100644
--- a/demo/src/main/java/com/herohan/uvcdemo/EntryActivity.java
+++ b/demo/src/main/java/com/herohan/uvcdemo/EntryActivity.java
@@ -53,6 +53,9 @@ public void onClick(View v) {
         XXPermissions.with(this)
                 .permission(needPermissions)
                 .request((permissions, all) -> {
+                    if(!all){
+                        return;
+                    }
 
                     if (v.getId() == R.id.btnBasicPreview) {
                         startActivity(new Intent(this, BasicPreviewActivity.class));