一直跳转到error页面，想各位看看是不是我代码有问题..
DBConn.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 DBConn {
public static Connection conn = null;
/**
* 得到数据库连接
/
public static Connection getConnection() throws ClassNotFoundException,
SQLException, InstantiationException, IllegalAccessException {
try {
// 指定驱动程序
Class.forName("com.mysql.jdbc.Driver");
// 建立数据库连结
conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/system","root", "root");
return conn;
} catch (Exception e) {
// 如果连接过程出现异常，抛出异常信息
throw new SQLException("驱动错误或连接失败！");
}
}
/
* 释放连接
*/
public static void closeConnection() throws Exception {
if (conn != null && !conn.isClosed())
System.out.println("数据库关闭");
conn.close();
}
}
UserDao.java
package dao;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import dao.User;
import dao.DBConn;
public class UserDao {
private Connection conn = null;
private PreparedStatement ps;
public User login(String username, String password) throws Exception{
//List<User> users = new ArrayList<User>();
String sql = "select * from user where username = ? and password = ?";
//List<User> users=new ArrayList<User>();
conn=DBConn.getConnection();
ps=conn.prepareStatement(sql);
ps.setString(1, username);
ps.setString(2, password);
ResultSet rs=ps.executeQuery();
while(rs.next()) {
User user=new User();
user.setUsername(rs.getString("username"));//得到数据库中列 传入账号到User对象
user.setPassword(rs.getString("password"));
//users.add(user);
}
return null;
}
}
LoginServlet.java
package servlet;
import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.mysql.jdbc.StringUtils;
import dao.DBConn;
import dao.User;
import dao.UserDao;
/**
-
Servlet implementation class LoginServlet
/
@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
DBConn db = new DBConn();
UserDao userDao = new UserDao();
User user = new User();
/*- @see HttpServlet#HttpServlet() */ public LoginServlet() { super(); // TODO Auto-generated constructor stub }
/**
- @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub doPost(request, response); }
/**
-
@see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
request.setCharacterEncoding("utf-8");
PrintWriter out= response.getWriter();String username=request.getParameter("username");
String password=request.getParameter("password");UserDao userDao = new UserDao();
User user = null; try { user = userDao.login(username,password); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } // 判断user是否为空 if(user != null){ // 转发到LoginSuccess.jsp页面 // getRequestDispatcher()是请求转发 request.getRequestDispatcher("register.jsp").forward(request, response); }else{ // 登录失败 request.getRequestDispatcher("error.jsp").forward(request, response); } }}
login.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
登录页面
用户名： 密码：
register.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
$Title$
成功！
error.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
$Title$
失败！
