Servlet技术入门（视频学习笔记）-2

public class ContextServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //获取配置文件中的上下文参数
        ServletContext context = getServletConfig().getServletContext();
        System.out.println(context.getInitParameter("username"));
        System.out.println(context.getInitParameter("password"));
        //获取当前的工程路径，格式：/工程路径
        System.out.println(context.getContextPath());
        //获取工程部署后在服务器硬盘的绝对路径
        /*
          getRealPath()返回一个给定虚拟路径的真实路径
          这个斜杆表示站点的根，也就是获取网站的根目录，即工程部署路径
            而/css就是表示该路径下的css文件夹
         */
        System.out.println(context.getRealPath("/"));
        System.out.println(context.getRealPath("/css"));
        System.out.println(context.getRealPath("/jpg"));
    }
}

public class ContextServlet2 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        ServletContext servletContext = getServletContext();
        System.out.println("Context2中获取域数据key1的值是：" + servletContext.getAttribute("key1"));
    }
}

public class RequestGetParameter extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("用户名" + req.getParameter("username"));
        System.out.println("密码" + req.getParameter("password"));
        String[] hobbies = req.getParameterValues("hobby");
        try{
            System.out.println("兴趣爱好" + Arrays.asList(hobbies));
        }catch (Exception e){
            System.out.println(e.getStackTrace());
        }
    }
}

public class Servlet1 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //查看请求的带来的数据
        String username = req.getParameter("username");
        System.out.println("servlet1中请求带来的数据:" + username);
        //处理业务
        //doSth
        username += "ahahha";
        System.out.println("业务1完成，username=" + username);
        //处理完业务，在request域中存储数据
        req.setAttribute("username",username);
        //询问servlet2的路径
        //请求转发必须以斜杆开始，表示http://ip:8080/工程名/
        RequestDispatcher requestDispatcher = req.getRequestDispatcher("/servlet2");
        //带着请求走向servlet
        requestDispatcher.forward(req,resp);
    }
}

public class Servlet2 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //查看请求带来的数据
        String username = request.getParameter("username");
        System.out.println("servlet2中请求带来的数据:" + username);
        //获取servlet1传入的数据
        Object obj = request.getAttribute("username");
        System.out.println("servlet1传入的数据:"+obj);
        //处理自己的业务
        System.out.println("业务处理完成");
    }
}

public class Response1 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //第一种方法
        /*
            System.out.println("我曾来过");
            //设置状态码302，表示重定向（已搬迁）
            response.setStatus(302);
            //设置响应头，说明新的地址在哪
            response.setHeader("Location","http://localhost:8080/myfirst/response2");
        */
        //第二种方法（推荐使用）
        response.sendRedirect("https://www.baidu.com");
    }
}