格式错误:org.springframework.dao.EmptyResultDataAccessException:错误的结果大小:预期为1,实际为0

时间:2018-09-04 03:02:02

标签: java spring eclipse spring-mvc derby

我建立了一个简单的登录页面,其中使用用户提供的用户名从数据库中获取所需行,并对照用户提供的值检查凭据。

我面临的问题是,如果用户输入数据库中不存在的用户名值,我将遇到此错误

  

org.springframework.dao.EmptyResultDataAccessException:不正确   结果大小:预期1,实际0

这意味着我的数据库没有包含所需用户名的任何行。

代码:

@Controller  
public class LoginController {  
    @Autowired  
    UserDao dao;
    @RequestMapping(value="/login",method = RequestMethod.POST)  
    public ModelAndView loginResult(HttpServletRequest req,HttpServletResponse res,RedirectAttributes redir,Model model) {

    String uname=req.getParameter("username");  
    String pwd=req.getParameter("pwd");  
    String dept = req.getParameter("dept");
    LoginInfoAdmin admin = dao.getEmpById(uname); 

if(uname.equals(admin.getUsername())&&pwd.equals(admin.getPassword())&&dept.equals(admin.getDept()))
            {
                req.getSession().setAttribute("uname",admin.getName());
                if(dept.equals((String)admin.getDept())){
                    return new ModelAndView("adminLoginResult", "message", message1); 
                }
                else if(dept.equals((String)admin.getDept())){
                    return new ModelAndView("EmployeeLoginResult","message",message1);
                }
                else{
                    return new ModelAndView("ManagerLoginResut","message",message1);
                }
            } 
else
        {
            return new ModelAndView("forward:index.jsp","message","Sorry Username Password Error");
}

索引页面:

<body>
    <b><span class="heading">LOGIN USER</span></b>
    <div class="container">
        <form action="login.html" method="Post">
            <div class="form_style">
            <input type="text" name="username" placeholder="Enter Username"/>
            <input type="password" name="pwd" placeholder="Enter password"/>
            <select name="dept">
                <option>IT</option>
                <option>ADMIN</option>
                <option>HR</option>
                <option>MARKETING</option>
            </select>
            <input type="Submit" value="submit">
            <span class="disp">${message}</span>
            </div>
        </form>
    </div>
</body>

UserDao (其中我使用模板连接到数据库并启动sql)

public class UserDao {
    JdbcTemplate template;  
    public void setTemplate(JdbcTemplate template) {  
        this.template = template;  
    }  
    public LoginInfoAdmin getEmpById(String username){  
        String sql="select * from ADMINLOGINDETAILS where username=?";  
        return template.queryForObject(sql, new Object[]{username},new BeanPropertyRowMapper<LoginInfoAdmin>(LoginInfoAdmin.class));  
    }  
}

我的问题是在触发查询后如何检查行是否存在。

1 个答案:

答案 0 :(得分:1)

有很多方法可以解决您的问题。一种方法是捕获在最高级别抛出的异常:

body .main {
  flex: 1;
  background: url("https://i.imgur.com/AsapsWY.png");
  background-size: 100% auto;
  background-repeat: no-repeat;
  width: 100%;
  position: relative;
  min-width: 600px;
  height: 100%;
}
body .main--flower img {
  position: absolute;
  bottom: 200px;
  right: 200px;
  max-width: 100px;
}
body .main--bin img {
  position: absolute;
  top: 400px;
  left: 200px;
  max-width: 100px;
}

另一种方法是将其向下捕获,如果缺少记录则返回null(然后在顶层检查null):

try {
    LoginInfoAdmin admin = dao.getEmpById(uname);
    if(uname.equals(admin.getUsername()) && pwd.equals(admin.getPassword()) && dept.equals(admin.getDept()))
    {
        req.getSession().setAttribute("uname",admin.getName());
        if(dept.equals((String)admin.getDept())){
            return new ModelAndView("adminLoginResult", "message", message1); 
        }
        else if(dept.equals((String)admin.getDept())){
            return new ModelAndView("EmployeeLoginResult","message",message1);
        }
        else{
            return new ModelAndView("ManagerLoginResut","message",message1);
        }
    } 
    else
    {
        return new ModelAndView("forward:index.jsp","message","Sorry Username Password Error");
    }
} catch (EmptyResultDataAccessException erdae) {
    return new ModelAndView("forward:index.jsp","message","Sorry Username Password Error");
}

编辑:对于您的DAO,最好返回public LoginInfoAdmin getEmpById(String username){ try { String sql="select * from ADMINLOGINDETAILS where username=?"; return template.queryForObject(sql, new Object[]{username},new BeanPropertyRowMapper<LoginInfoAdmin>(LoginInfoAdmin.class)); } catch (EmptyResultDataAccessException erdae) { return null; } } 。这样,如果没有匹配的记录,您可以返回Optional<LoginInfoAdmin>