【Web入门系列】初探HttpServletResponse

public class ResponseServlet extends HttpServlet { ???/** ????* 1、tomcat服务器把请求信息封装到HttpServletRequest对象，且把响应信息封装到HttpServletResponse ????* 2、tomcat服务器调用doGet方法，传入request，和response对象 ????* 3、通过response对象改变响应信息 ????* 4、tomcat服务器把response对象的内容转换成响应格式内容，再发送给浏览器解析 ????* @param request ????* @param response ????* @throws ServletException ????* @throws IOException ????*/ ???public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { ???????/** ????????* 设置响应实体内容编码 ????????*/ ???????//response.setCharacterEncoding("utf-8"); ???????/** ????????* 3.1 响应行 ????????*/ ???????//修改状态码 ???????//response.setStatus(404); ???????// 发送404的状态码+404的错误页面 ???????//response.sendError(404); ???????/** ????????* 3.2 响应头 ????????*/ ???????//response.setHeader("server", "JBoss"); ???????/** ????????* 3.3 实体内容(浏览器直接能够看到的内容就是实体内容) ????????*/ ???????//字符内容。 ???????//response.getWriter().write("hello world"); ???????//字节内容 ???????//response.getOutputStream().write("hello world".getBytes()); ???????/** ????????* 请求重定向： 发送一个302状态码 + location的响应头 ????????*/ ???????//发送一个302状态码 ???????//response.setStatus(302); ???????//location的响应头 ???????//response.setHeader("location", "/myweb/adv.html"); ???????//请求重定向简化写法 ???????//response.sendRedirect("/myweb/adv.html"); ???????/** ????????* 定时刷新 ????????* 原理：浏览器认识refresh头，得到refresh头之后重新请求当前资源 ????????*/ ???????//每隔1秒刷新次页面 ???????//response.setHeader("refresh", "1"); ???????/** ????????* 隔n秒之后跳转另外的资源 ????????*/ ???????//隔3秒之后跳转到adv.html ???????//response.setHeader("refresh", "3;url=/myweb/adv.html"); ???????// 打开图片 ???????/*response.setContentType("image/jpg"); ???????File file = new File("e://test.jpg"); ???????FileInputStream inputStream = new FileInputStream(file); ???????int len = 0; ???????byte[] byt = new byte[1024]; ???????while ((len = inputStream.read(byt)) != -1){ ???????????response.getOutputStream().write(byt,0,len); ???????}*/ ???????// 以下载的方式打开图片 ???????File file = new File("e://image.jpg"); ???????FileInputStream inputStream = new FileInputStream(file); ???????response.setHeader("Content-Disposition","attachment; filename="+file.getName()); ???????int len = 0; ???????byte[] byt = new byte[1024]; ???????while ((len = inputStream.read(byt)) != -1){ ???????????response.getOutputStream().write(byt,0,len); ???????} ???} ???/** ????* ????* @param request ????* @param response ????* @throws ServletException ????* @throws IOException ????*/ ???public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { ???????doGet(request,response); ???}}