Nio 读取UTF-8文件出现中文乱码

String filePath = "viewflow.html" ;
StringBuilder sb = new StringBuilder(1024*10);
try {
BufferedReader reader =  new BufferedReader(new FileReader(new File(filePath)));
CharBuffer charBuff = CharBuffer.allocate(1024);
int length = -1 ;
while((length = reader.read(charBuff)) > 0 ){
charBuff.flip();
sb.append(charBuff,0,length);
}
System.out.println(sb.toString());
} catch (FileNotFoundException e1) {
e1.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}