原理：Files.newBufferedReader(Path path, Charset charset)没有实现编码容错

遍历所有的字符集，读取文件，如果不报MalformedInputException，即可认为编码格式正确。

代码如下：

1 public class CharsetTest { 2     public static final Path path = Paths.get(""); 3  4     public static void main(String[] args) { 5         Map
     
       map = Charset.availableCharsets(); 6         List
      
        retval = map.values().stream().filter(CharsetTest::testCharset).collect(Collectors.toList()); 7     } 8  9     private static boolean testCharset(Charset charset) {10         BufferedReader br;11         try {12             br = Files.newBufferedReader(path, charset);13         } catch (IOException e) {14             System.out.println("Read file error!");15             return false;16         }17 18         try {19             while (br.readLine() != null) {20 21             }22         } catch (MalformedInputException e) {23             System.out.println("MalformedInputException");24             return false;25         } catch (IOException e) {26             System.out.println("IOException happens!");27             return false;28         }29 30         return true;31     }32 }