Day13--JavaWeb学习之Servlet后端渲染界面

基于Day12中登录页面实现的修改，这里实现的是如果登录成功，跳到LoginSuccess页面中展示后端查询到数据库中的信息，并实现在浏览器实现插入数据和删除数据（mybaits）。

当输入账号密码正确后进入LoginSuccess页面，通过resp.getWriter来编写后端需要渲染的页面。

数据删除：

后端渲染数据展示的页面

在数据展示页面增加删除操作按钮，让点击后跳转到**@WebServlet("/DelUser")，真正实现数据删除的地方**

java 复制代码

@WebServlet("/LoginSuccess")
public class LoginSuccess extends HttpServlet {
    //收参数
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        List<Student> info = (List<Student>) req.getAttribute("AllInfo");
        PrintWriter wr = resp.getWriter();
        wr.write("<!DOCTYPE html>");
        wr.println("<html>");
        wr.println("<head>");
        wr.write("</head>");
        wr.println("<body>");
        wr.write("<table cellpadding='2' cellspacing='2' center='100%' border='1'>");
        wr.write("<tr><th>学号</th><th>姓名</th><th>性别</th><th>年龄</th><th>专业</th><th>操作</th></tr>");
        wr.write("<tr><a href='Insert'>信息录入</a></tr>");
        for (int i = 0; i < info.size(); i++) {
            wr.write("<tr>");
            wr.write("<td>" + info.get(i).getSno() + "</td>");
            wr.write("<td>" + info.get(i).getName() + "</td>");
            wr.write("<td>" + info.get(i).getSex() + "</td>");
            wr.write("<td>" + info.get(i).getAge() + "</td>");
            wr.write("<td>" + info.get(i).getMajor() + "</td>");
            wr.write("<td> <a onclick=\"if(confirm('确认删除吗？'))return true;return false;\" " +
                    "href=DelUser?Sno="+ info.get(i).getSno()+">删除</a></td>");
            wr.write("</tr>");
        }
        wr.write("</table>");

        wr.println("</body>");
        wr.println("</html>");

    }
}

实现执行删除的操作代码：

java 复制代码

@WebServlet("/DelUser")
public class DelUser extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("UTF-8");
        resp.setContentType("text/html;charset=utf-8");
        String Sno = req.getParameter("Sno");
        System.out.println("Sno = " + Sno);
        GetMapper getMapper = new GetMapper();
        getMapper.delete(Integer.valueOf(Sno));
        ArrayList<Student> stu = getMapper.selectAll();
        req.setAttribute("AllInfo", stu);
        if (!stu.isEmpty()) {
            req.getRequestDispatcher("LoginSuccess").forward(req, resp);
        }
    }
}

数据的插入：

后端渲染数据插入的页面

java 复制代码

@WebServlet("/Insert")
public class Insert extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("UTF-8");
        resp.setContentType("text/html;charset=utf-8");
        PrintWriter wr = resp.getWriter();
        wr.println("<html>");
        wr.println("<head>");
        wr.println("<title>Servlet Insert</title>");
        wr.println("</head>");
        wr.println("<body>");
        wr.println("<h1>Servlet Insert </h1>");
        wr.write("<div class='container'> " +
                "<form action='InsertOk'>"+
                "学号：<input type='text' name='sno'><br>" +
                "姓名：<input type='text' name='name'><br>" +
                "性别：<input type='text' name='sex'><br>" +
                "年龄：<input type='text' name='age'><br>" +
                "专业：<input type='text' name='major'><br>"+
                "<button>提交添加</button>" +
                "</form>"+
                "</div>");
        wr.println("</body>");
        wr.println("</html>");
    }
}

后端处理数据插入的代码：

java 复制代码

@WebServlet("/InsertOk")
public class InsertOk extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        req.setCharacterEncoding("UTF-8");
        resp.setContentType("text/html;charset=utf-8");

        String major = req.getParameter("major");
        String age = req.getParameter("age");
        String sex = req.getParameter("sex");
        String name = req.getParameter("name");
        String sno = req.getParameter("sno");
        Student student = new Student(Integer.valueOf(sno),name,sex,Integer.valueOf(age),major);
        GetMapper getMapper = new GetMapper();
        getMapper.insert(student);
        ArrayList<Student> stu = getMapper.selectAll();
        req.setAttribute("AllInfo", stu);
        if (!stu.isEmpty()) {
            req.getRequestDispatcher("LoginSuccess").forward(req, resp);
        }
    }
}