refactor:代码优化

src/main/java/text/TextFileHandlerFactory.java

+package text;
+
+import handler.AbstractFileHandler;
+import handler.FileHandlerFactory;
+
+import java.io.File;
+
+public class TextFileHandlerFactory implements FileHandlerFactory {
+    @Override
+    public AbstractFileHandler create(File file) {
+        return new TextHandler(file);
+    }
+}