diff --git a/src/File.php b/src/File.php
index 780242c..805e83e 100644
--- a/src/File.php
+++ b/src/File.php
@@ -23,11 +23,11 @@ abstract class File extends FileSystem
 {
     use ReadTrait;
 
-    const FORMAT_JSON = 'json';
-    const FORMAT_PHP  = 'php';
-    const FORMAT_INI  = 'ini';
-    const FORMAT_YML  = 'yml';
-    const FORMAT_YAML = 'yml';
+    public const FORMAT_JSON = 'json';
+    public const FORMAT_PHP  = 'php';
+    public const FORMAT_INI  = 'ini';
+    public const FORMAT_YML  = 'yml';
+    public const FORMAT_YAML = 'yml';
 
     /**
      * 获得文件名称
diff --git a/src/FileFinder.php b/src/FileFinder.php
index fac7a49..98e179d 100644
--- a/src/FileFinder.php
+++ b/src/FileFinder.php
@@ -28,10 +28,10 @@
  */
 final class FileFinder implements \IteratorAggregate, \Countable
 {
-    const ONLY_FILE        = 1;
-    const ONLY_DIR         = 2;
-    const IGNORE_VCS_FILES = 1;
-    const IGNORE_DOT_FILES = 2;
+    public const ONLY_FILE        = 1;
+    public const ONLY_DIR         = 2;
+    public const IGNORE_VCS_FILES = 1;
+    public const IGNORE_DOT_FILES = 2;
 
     /** @var array */
     private static $vcsPatterns = ['.svn', '_svn', 'CVS', '_darcs', '.arch-params', '.monotone', '.bzr', '.git', '.hg'];
diff --git a/src/FileSystem.php b/src/FileSystem.php
index b88bac1..e6cd7c3 100644
--- a/src/FileSystem.php
+++ b/src/FileSystem.php
@@ -31,8 +31,8 @@ public static function isAbsPath(string $path): bool
         }
 
         if (
-            $path{0} === '/' ||  // linux/mac
-            1 === preg_match('#^[a-z]:[\/|\\\]{1}.+#i', $path) // windows
+            \strpos($path, '/') === 0 ||  // linux/mac
+            1 === \preg_match('#^[a-z]:[\/|\\\]{1}.+#i', $path) // windows
         ) {
             return true;
         }
@@ -63,9 +63,9 @@ public static function isAbsolutePath(string $file): bool
      */
     public static function pathFormat(string $dirName): string
     {
-        $dirName = str_ireplace('\\', '/', trim($dirName));
+        $dirName = (string)\str_ireplace('\\', '/', trim($dirName));
 
-        return substr((string)$dirName, -1) === '/' ? $dirName : $dirName . '/';
+        return \substr($dirName, -1) === '/' ? $dirName : $dirName . '/';
     }
 
     /**
@@ -239,10 +239,8 @@ public static function chown($files, string $user, $recursive = false)
                 if (true !== lchown($file, $user)) {
                     throw new IOException(sprintf('Failed to chown file "%s".', $file));
                 }
-            } else {
-                if (true !== chown($file, $user)) {
-                    throw new IOException(sprintf('Failed to chown file "%s".', $file));
-                }
+            } elseif (true !== chown($file, $user)) {
+                throw new IOException(sprintf('Failed to chown file "%s".', $file));
             }
         }
     }
@@ -255,7 +253,7 @@ public static function chown($files, string $user, $recursive = false)
      */
     public static function getIterator(string $srcDir, callable $filter): \RecursiveIteratorIterator
     {
-        if (!$srcDir || !file_exists($srcDir)) {
+        if (!$srcDir || !\file_exists($srcDir)) {
             throw new \InvalidArgumentException('Please provide a exists source directory.');
         }