请问下面的字符串我要从<?xml version="1.0"开始截取到最后</soap:Envelope>怎么实现，用substring只能从哪个字符开始

Question

HTTP/1.1 200 OK
Server: Microsoft-IIS/5.0
Date: Sat, 06 Aug 2005 07:20:45 GMT
X-Powered-By: ASP.NET
SessionTimeOut: 152
X-AspNet-Version: 1.1.4322
Cache-Control: private, max-age=0
Content-Type: text/xml; charset=utf-8
Content-Length: 1179<?xml version="1.0" encoding="utf-8"?><soap:Envelope xmlns:soap="http://schemas.
xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance
" xmlns:xsd="http://www.w3.org/2001/XMLSchema"><soap:Body><authNo>100003923</authNo></soap:Body
></soap:Envelope>

Answer 1

String str="....";//很长的这个
String substring=str.substring(str.indexOf("<?xml"));