帮我看看是什么问题呢，为什么读网页源文件会有乱码java

public void whttp(String path,String www){

File f= new File(path);
FileWriter fw=null;
String line = null;
try
{
URL url = new URL(www);
URLConnection conn = url.openConnection();
BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));

while ((line = reader.readLine()) != null)
{
fw=new FileWriter(f,true);
fw.write(line);
fw.flush();
}

reader.close();
fw.close();
}
catch (MalformedURLException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}

}