使用1.7 Files，实现编码探测

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：

public class CharsetTest {
    public static final Path path = Paths.get("");

    public static void main(String[] args) {
        Map<String, Charset> map = Charset.availableCharsets();
        List<Charset> retval = map.values().stream().filter(CharsetTest::testCharset).collect(Collectors.toList());
    }

    private static boolean testCharset(Charset charset) {
        BufferedReader br;
        try {
            br = Files.newBufferedReader(path, charset);
        } catch (IOException e) {
            System.out.println("Read file error!");
            return false;
        }

        try {
            while (br.readLine() != null) {

            }
        } catch (MalformedInputException e) {
            System.out.println("MalformedInputException");
            return false;
        } catch (IOException e) {
            System.out.println("IOException happens!");
            return false;
        }

        return true;
    }
}