外部类——StreamToString

public class StreamToString {

public static String streamToStr(InputStream inputStream, String chartSet){

StringBuilder builder=new StringBuilder();
try {
BufferedReader br=new BufferedReader(new InputStreamReader(inputStream,chartSet));
String con;
while ((con=br.readLine())!=null){
builder.append(con);
}

br.close();
return builder.toString();

} catch (Exception e) {
e.printStackTrace();
}

return "";
}
}