code style optimization (#3418)

* code style optimize

* Fix check bug

* Fix error logic code

sharding-ui/sharding-ui-backend/src/main/java/org/apache/shardingsphere/ui/repository/impl/YamlRegistryCenterConfigsRepositoryImpl.java

@@ -30,6 +30,7 @@ import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
 
 /**
  * Implementation of Registry center configs repository.
@@ -52,7 +53,7 @@ public final class YamlRegistryCenterConfigsRepositoryImpl implements RegistryCe
         }
         
         try (FileInputStream fileInputStream = new FileInputStream(file);
-             InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream, "UTF-8")) {
+             InputStreamReader inputStreamReader = new InputStreamReader(fileInputStream, StandardCharsets.UTF_8)) {
             return new Yaml(new Constructor(RegistryCenterConfigs.class)).loadAs(inputStreamReader, RegistryCenterConfigs.class);
         } catch (IOException e) {
             throw new ShardingUIException(ShardingUIException.SERVER_ERROR, "load config error");

sharding-ui/sharding-ui-backend/src/main/java/org/apache/shardingsphere/ui/security/AuthenticationFilter.java

@@ -43,6 +43,8 @@ public final class AuthenticationFilter implements Filter {
     
     private static final String LOGIN_URI = "/api/login";
     
+    private final Gson gson = new Gson();
+    
     @Setter
     private UserAuthenticationService userAuthenticationService;
     
@@ -72,14 +74,14 @@ public final class AuthenticationFilter implements Filter {
     
     private void handleLogin(final HttpServletRequest httpRequest, final HttpServletResponse httpResponse) {
         try {
-            UserAccount user = new Gson().fromJson(httpRequest.getReader(), UserAccount.class);
+            UserAccount user = gson.fromJson(httpRequest.getReader(), UserAccount.class);
             if (userAuthenticationService.checkUser(user)) {
                 httpResponse.setContentType("application/json");
                 httpResponse.setCharacterEncoding("UTF-8");
                 Map<String, Object> result = new HashMap<>();
                 result.put("username", userAuthenticationService.getUsername());
                 result.put("accessToken", userAuthenticationService.getToken());
-                httpResponse.getWriter().write(new Gson().toJson(ResponseResultUtil.build(result)));
+                httpResponse.getWriter().write(gson.toJson(ResponseResultUtil.build(result)));
             } else {
                 respondWithUnauthorized(httpResponse);
             }

sharding-ui/sharding-ui-backend/src/main/java/org/apache/shardingsphere/ui/util/ConfigurationYamlConverter.java

@@ -38,7 +38,6 @@ import org.apache.shardingsphere.core.yaml.swapper.impl.MasterSlaveRuleConfigura
 import org.apache.shardingsphere.core.yaml.swapper.impl.ShardingRuleConfigurationYamlSwapper;
 import org.apache.shardingsphere.orchestration.yaml.config.YamlDataSourceConfiguration;
 import org.apache.shardingsphere.orchestration.yaml.swapper.DataSourceConfigurationYamlSwapper;
-
 import java.util.Map;
 import java.util.Properties;