读取帮助类（StreamTools）

public class StreamTools {    public static String readStreamTools(InputStream is){        try {            ByteArrayOutputStream baos=new ByteArrayOutputStream();            byte[] buffer=new byte[1024];            int len=0;            while ((len=is.read(buffer))!=-1){                baos.write(buffer,0,len);            }            return baos.toString();        } catch (Exception e) {            e.printStackTrace();        }        return null;    }}