本文目录一览：
jsp页面的代码
Vector v=(Vector)application.getAttribute(“Mess”);//这行代码是声明一个Vector 变量，此变量是一个键值对象
其他的太 多了不想写
求jsp代码，题目如下：
rect.jsp
%@ page language=”java” pageEncoding=”utf-8″%
!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.01 Transitional//EN”
html
head
/head
body
form action=”com.jsp” method=”post”
请输入正方形的边长: input type=”text” name=”length” width=”100px”
br/ br/
input type=”submit” value=”submit”
/form
/body
/html
com.jsp
%@ page language=”java” pageEncoding=”utf-8″%
!DOCTYPE HTML PUBLIC “-//W3C//DTD HTML 4.01 Transitional//EN”
html
head
/head
body
%
String length=request.getParameter(“length”);
float s=0;
try{
s=Float.parseFloat(length);
}
catch (Exception e)
{
out.print(“请输入有效数值brbr”);
s=0;
}
%
正方形周长为： %=4*s %br/
正方形面积为： %=s*s %br/
/body
/html
求大神写一下jsp的简单的注册界面代码。
1.需要一个jsp页面：
//login.jsp核心代码：
form action=”${pageContext.request.contextPath}/servlet/UserServlet” method=”post”
input type=”text” name=”loginname” /input type=”password” name=”password”/
input type=”submit” value=”登录”/
/form
2.需要一个servlet来验证登录信息
//UserServlet 核心代码
class UserServlet extends HttpServlet{
protected void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
process(request, response);
}
protected void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
process(request, response);
}
private void process(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
PrintWriter pw = response.getWriter();
request.setCharacterEncoding(“UTF-8”);
response.setContentType(“text/html”);
String loginname = request.getParameter(“loginname”);
String password = request.getParameter(“password”);
//创建一个service来处理业务逻辑（包括查询数据库操作）
UserService service = new UserService();
boolean bool = service.validateUser(loginname,password);
if(!bool){
pw.println(“用户名或密码错误”);
}else{
pw.println(“登录成功”);
}
}
3.需要一个service处理业务逻辑（包括查询数据库操作）
//UserService 核心代码
public class UserService{
/**
*查询数据库验证用户是否存在，返回boolean
*/
public boolean validateUser(String loginname,String password){
boolean bool = false;
Connection conn = null;
PreparedStatement ps = null;
//这里以mysql为例
try {
Class.forName(“com.mysql.jdbc.Driver”).newInstance();
conn = DriverManager.getConnection(“jdbc:mysql://localhost:3306/test”, “root”, “”);
String sql = “select login_name,pass_word from t_user where login_name=? and pass_word=?”;
ps = conn.prepareStatement(sql);
ps.setString(0, loginname);
ps.setString(1, password);
ResultSet rs = ps.executeQuery();
if(rs.next()){
bool = true;
}
} catch (Exception e) {
e.printStackTrace();
} finally{
try {
if(conn != null){
conn.close();
conn = null;
}
if(ps != null){
ps.close();
ps = null;
}
} catch (SQLException e) {
e.printStackTrace();
}
}
return bool;
}
}
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