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UsrService中
@Override
public Boolean UserExist(String username) {
// TODO Auto-generated method stub
User user = userDao.findUser(username);
return user!=null;
}在Dao中
@Override
public User findUser(String username) {
// TODO Auto-generated method stub
User user=null;
Connection conn =null;
PreparedStatement ps=null;
ResultSet rs=null;
try {
conn=DBUtils.getConnection();
String sql="select * from t_user where username=?";
ps = conn.prepareStatement(sql);
ps.setString(1, username);
rs=ps.executeQuery();
while(rs.next()){
user= new User();
user.setId(rs.getInt("id"));
user.setUsername(rs.getString("username"));
user.setPassword(rs.getString("password"));
user.setEmail(rs.getString("email"));
user.setBirthday(rs.getDate("birthday"));
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally{
DBUtils.closeAll(conn, ps, null);
}
return user;
}在RegisterServlet中 写
//判断数据库是否有重复用户名
if(userService.UserExist(user.getUsername())){
//回到注册页面，给个提示
uForm.getErr().put("username","用户已经存在");
request.setAttribute("uf", uForm);
request.getRequestDispatcher("/register.jsp").forward(request, response);
}else {
//注册用户
userService.register(user);
response.getWriter().write("注册成功,3秒后转回主页");
response.setHeader("refresh", "3;url="+request.getContextPath()+"/index.jsp");
}