数据库test 中建个表 stu(stuid 主键 自动增长 ，用户名，密码，年龄)

1.设计一个注册页面，实现用户注册功能
2.设计一个登陆页面，实现用户名密码登陆
3.两个页面可以互相超链接

BaseDao.java

package dao;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class BaseDao {

// 获取连接  
public static Connection getConnection() {  
    Connection conn = null;  
    try {  
        Class.forName("com.mysql.jdbc.Driver");  
        // 2.建立连接  
        conn = DriverManager.getConnection(  
                "jdbc:mysql://localhost:3306/test", "root", "root");  
    } catch (Exception e) {  
        e.printStackTrace();  
    }  
    return conn;  
}

// 关闭连接  
public static void closeAll(Connection con, PreparedStatement ps, ResultSet rs) {  
    try {  
        if (rs != null)  
            rs.close();  
        if (ps != null)  
            ps.close();  
        if (con != null)  
            con.close();

    } catch (SQLException e) {  
        e.printStackTrace();  
    }  
}

}

stuDao.java

package dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class stuDao {

public static void main(String\[\] args) {  
    stuDao s=new stuDao();  
    String sname="张三";  
    int pwd=12;  
    System.out.println(s.login(sname, pwd));  
}  
public student login(String sname, int pwd) {  
    Connection conn = BaseDao.getConnection();  
    student s=null;  
    PreparedStatement ps = null;  
    ResultSet rs = null;  
    try {  
        String sql = "select \* from stu where sname=? and pwd=?";  
        ps = conn.prepareStatement(sql);  
        ps.setString(1, sname);  
        ps.setInt(2, pwd);  
        rs = ps.executeQuery();  
        if (rs.next()) {  
            s=new student();  
            String name=rs.getString("sname");  
            s.setSname(name);  
            return s;  
        }  
    } catch (SQLException e) {  
        // TODO Auto-generated catch block  
        e.printStackTrace();  
    } finally {  
        BaseDao.closeAll(conn, ps, rs);  
    }  
    return s;  
}

public int reg(String sname, int pwd, int age) {  
    Connection conn = BaseDao.getConnection();  
    PreparedStatement ps = null;  
    int r = -1;  
    try {  
        String sql = "insert into stu(sname,pwd,age) values(?,?,?)"; // 2个占位符  
        // 4.执行SQL语句  
        ps = conn.prepareStatement(sql);  
        ps.setString(1, sname);  
        ps.setInt(2, pwd);  
        ps.setInt(3, age);  
        r = ps.executeUpdate();// 增删改都用这个  
    } catch (SQLException e) {  
        // TODO Auto-generated catch block  
        e.printStackTrace();  
    } finally {  
        BaseDao.closeAll(conn, ps, null);  
    }  
    return r;

}

}

student.java

package dao;

public class student {
String sname;
int pwd;
int age;
public String getSname() {
return sname;
}
public void setSname(String sname) {
this.sname = sname;
}
public int getPwd() {
return pwd;
}
public void setPwd(int pwd) {
this.pwd = pwd;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
@Override
public String toString() {
return "student [sname=" + sname + ", pwd=" + pwd + ", age=" + age
+ "]";
}

}

student.jsp

<%@ page language="java" import="java.util.\*" pageEncoding="utf-8"%>

<%

%>

学生姓名： 账号密码：

slogin.jsp

<%@ page language="java" import="java.util.\*" pageEncoding="utf-8"%>

<%@ page import="dao.stuDao"%>
<% String name = request.getParameter("sname"); String spwd = request.getParameter("spwd"); String sname = new String(name.getBytes("ISO-8859-1"), "utf-8"); try { int pwd = Integer.parseInt(spwd); stuDao studao = new stuDao(); if (studao.login(sname, pwd) != null) { out.println("登录成功！"); } else { out.println("登陆失败！"); out.println("三秒后跳转到主页面…"); response.setHeader("refresh", "3;url=student.jsp"); } } catch (Exception e) { out.println("异常！！"); out.println("三秒后跳转到主页面…"); response.setHeader("refresh", "3;url=student.jsp"); } %>
返回

slogon.jsp

<%@ page language="java" import="java.util.\*" pageEncoding="utf-8"%>

<%

%>

请输入信息来完成注册…

用户名： 密码: 年龄:

返回

slogon_link.jsp

<%@ page language="java" import="java.util.\*" pageEncoding="utf-8"%>

<%@ page import="dao.stuDao"%>
<% String sname = request.getParameter("sname"); String spwd = request.getParameter("spwd"); String sage = request.getParameter("sage"); String name=new String(sname.getBytes("ISO-8859-1"),"utf-8"); int pwd = Integer.parseInt(spwd); int age = Integer.parseInt(sage); stuDao s = new stuDao(); if (s.reg(sname, pwd, age) != -1) { out.println("注册成功！"); out.println("三秒后跳转到主页…"); response.setHeader("refresh", "3;url=student.jsp"); } else { out.println("注册失败！"); out.println("三秒后跳转到主页…"); response.setHeader("refresh", "3;url=student.jsp"); } %>