jsp复习题

b)Registerservlet.java(注册功能的servlet)

public class Registerservlet extends HttpServlet { public void init(ServletConfig config) throws ServletException {

super.init(config); }

public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

request.setCharacterEncoding(\

String username = request.getParameter(\

String userpass = request.getParameter(\ User user = new User();

boolean isExist = user.usernameIsExist(username); if(isExist ==false) { RequestDispatcher dispatcher = request.getRequestDispatcher(\

dispatcher.forward(request, response); }else {

response.setContentType(\ response.getWriter().write(\用户名已存在......\ } }

Public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

doGet(request, response); } }

c)Web.xml

Registerservlet

.servlet.Registerservlet

Registerservlet /registerservlet

d)Javabean命名为user.java public class Users {

private String username; private String userpass; Connection con = null;

PreparedStatement pre = null; ResultSet rs = null; //判断用户名是否存在

public boolean usernameIsExist(String username) {

boolean isExist = null;

String sql = \* from user where username='\ try {

Class.forName(\con = DriverManager.getConnection(\pre = con.prepareStatement(sql);

rs = pre.executeQuery(); if(rs.next()) { isExist = true; }else {

isExist = false; }

} catch (Exception e) { }

return isExist ; }

public String getUsername() { return username; }

public void setUsername(String username) { this.username = username; }

public String getUserpass() { return userpass; }

public void setUserpass(String userpass) { this.userpass = userpass; } }

16、采用MVC模式实现web应用。用户可以通过JSP页面输入三角形三边的长度的一个servlet控制器，控制器负责计算三角形的面积，并将面积存放在数据模型中，然后请求JSP页面显示数据模型中的面积。

写出几个文件的关键代码（或程序流程，尽量采用代码），具体要