1、在一个请求中跨越多个Servlet
2、多个Servlet在一个请求中,他们共享request对象。就是在Servlet01中setAttribute()保存数据在Servlet02中由getAttribute()取出数据
3、在Servlet01转发到Servlet02,那么整个请求都是由Servlet02来完成,Servlet01不再插手
4、Servlet01 包含Servlet02,那么两个Servlet共同完成请求
5、请求转发和请求包含都需要使用一个对象RequestDispatcher。
Servlet01:
public class DemoServlet01 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//从数据库获取数据
UserService service = new UserService();
List<User> userList = service.getUserList();
//把数据放到request对象中
request.setAttribute("userList", userList);
//获取重定向对象
RequestDispatcher requestDispatcher = request.getRequestDispatcher("/DemoServlet03");
//重定向对象执行操作
requestDispatcher.forward(request, response);
}
}
Servlet02:
public class DemoServlet02 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//从request中取出数据
List<User> list = (List<User>) request.getAttribute("userList");
//响应到请求的客户端
response.setContentType("text/html;charset=utf-8");
for (User user : list) {
response.getWriter().print(user);
} }
}
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