JAVA 亂碼

在讀取文件的時候，若文件中有中文，應該使用字符流的方式來讀取文件，若用字節流會出現亂碼情況！

File file = new File(Environment.getExternalStorageDirectory(), "c.txt");

InputStream is = new FileInputStream(file);
InputStreamReader isr = new InputStreamReader(is, "GB2312");
BufferedReader br = new BufferedReader(isr);
while((temp = br.readLine()) != null){
sb.append(temp);
}