Android访问struts2的返回值问题

服务器端：response.getWriter().println(this.jsonString);
Android客户端：String json = HttpUtil.postRequest(url, map);
最后输出的确是：
01-09 13:45:47.777: INFO/System.out(292):<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
01-09 13:45:47.777: INFO/System.out(292): <html>
01-09 13:45:47.787: INFO/System.out(292): <head>
01-09 13:45:47.787: INFO/System.out(292): <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
01-09 13:45:47.797: INFO/System.out(292): <title>Insert title here</title>
01-09 13:45:47.807: INFO/System.out(292): 
01-09 13:45:47.807: INFO/System.out(292): </head>
01-09 13:45:47.807: INFO/System.out(292): <body>
01-09 13:45:47.807: INFO/System.out(292):     {"result":"0000","sequence_id":"1111111001","type":"login","body":{"result":1}}
01-09 13:45:47.807: INFO/System.out(292): </body>
01-09 13:45:47.807: INFO/System.out(292): </html>我想得到{"result":"0000","sequence_id":"1111111001","type":"login","body":{"result":1}}
字符串，应该怎样操作呢？感谢大家！