import java.io.*;

public class charsetTest {
   public static String charsetType(String fileName) throws IOException {
      BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(fileName), "utf-8"));
      String str=reader.readLine();
      int len1=str.length();
      
      reader = new BufferedReader(new InputStreamReader(new FileInputStream(fileName), "gbk"));
      str=reader.readLine();
      int len2=str.length();
      if(len1<=len2){
         return "utf-8";
      }
      else{
         return "gbk";
      }
      
   }

   public static void main(String[] args) throws IOException {
      System.out.println("gbk.txt："+charsetType("gbk.txt"));
      System.out.println("utf.txt："+charsetType("utf.txt"));
   }
}

 在日常处理中文文本的过程中发现的一种有趣现象，实际运行可准确判断中文字符编码类型，但有无例外情况尚不可知