一、HttpServletResponse
HttpServletResponse表示一个HTTP响应
Servlet 中的 doXXX 方法的目的就是根据请求计算得到相应, 然后把响应的数据设置到 HttpServletResponse 对象中
然后 Tomcat 就会把这个 HttpServletResponse 对象按照 HTTP 协议的格式, 转成一个字符串, 并通过 Socket 写回给浏览器
1.1 HttpServletResponse核心方法
1.2 方法演示
@WebServlet("/status")
public class StatusServlet extends HttpServlet {@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {resp.setStatus(404);resp.setContentType("text/heml;charset=utf-8");resp.getWriter().write("返回404");}
}
使用Fiddler抓包得到的响应：
HTTP/1.1 404
Content-Type: text/heml;charset=utf-8
Content-Length: 9
Date: Wed, 15 Nov 2023 06:36:28 GMT返回404
1.3 通过header实现自动刷新
给HTTP响应中设置Refresh:时间
@WebServlet("/refresh")
public class RefreshServlet extends HelloServlet{@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {// 每隔 1s 自动刷新一次.resp.setHeader("Refresh", "1");resp.getWriter().write("time=" + System.currentTimeMillis());}
}
响应：
HTTP/1.1 200
Refresh: 1
Content-Length: 18
Date: Wed, 15 Nov 2023 06:46:09 GMTtime=1700030769011
1.4 通过header实现自动重定向
@WebServlet("/redirect")
public class RedirectServlet extends HelloServlet{@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {// 用户访问这个路径的时候, 自动重定向到 搜狗主页 .resp.sendRedirect("https://www.sogou.com");}
}
HTTP/1.1 302
Location: https://www.sogou.com
Content-Length: 0
Date: Wed, 15 Nov 2023 06:54:19 GMT
