add secure phone

example/lib/data/extension/example_string_ext.dart

@@ -20,6 +20,11 @@ class _ExampleStringExtState extends State<ExampleStringExt> {
             title: Text('18888888888'),
             subtitle: Text('18888888888'.phone),
           ),
+          ListTile(
+            leading: Chip(label: Text('.securePhone')),
+            title: Text('18888888888'),
+            subtitle: Text('18888888888'.securePhone),
+          ),
         ],
       ),
     );

lib/extension/string_extension.dart

@@ -1,10 +1,31 @@
 extension PhoneExt on String {
+  List get _parsePhone {
+    if (this.length < 11)
+      return [];
+    else
+      return [
+        this.substring(0, 3),
+        this.substring(3, 7),
+        this.substring(7, 11),
+      ];
+  }
+
+  bool get _validPhone => _parsePhone.isNotEmpty;
+
+  ///电话号码加分隔线
+  ///
+  ///example 18888888888 => 188-8888-8888
   String get phone {
-    ///电话号码加分隔线
-    return (this.substring(0, 3) +
-        '-' +
-        this.substring(3, 7) +
-        '-' +
-        this.substring(7, 11));
+    if (!_validPhone)
+      return this;
+    else
+      return '${_parsePhone[0]}-${_parsePhone[1]}-${_parsePhone[2]}';
+  }
+
+  String get securePhone {
+    if (!_validPhone)
+      return this;
+    else
+      return '${_parsePhone[0]}****${_parsePhone[2]}';
   }
 }