ssm的搭建见上一章

1.数据协议层

public User selectByLoginnameAndPassword(@Param("loginname")String loginname,@Param("password") String password);

2.服务协议层

 User login(String loginname,String password);

3.服务层

@Autowired
private UserDao userDao;
public User login(String loginname, String password) {
        return userDao.selectByLoginnameAndPassword(loginname, password);
    }

4.数据实现层(mybatis)

<mapper namespace="com.yongxing.manager.dao.UserDao"><select id="selectByLoginnameAndPassword" resultType="com.yongxing.manager.domain.User" >
  select * from user_inf where loginname=#{loginname} and password=#{password}
</select>

5.控制层

@Controller
public class UserController {
    @Autowired
    private UserService userServcie;
    @RequestMapping("/checklogin")
    @ResponseBody
   public User checklogin( String loginname,String paasword,HttpSession session){
        System.out.println(loginname);
        User user =userServcie.login(loginname, paasword);
        if(user!=null) {
            session.setAttribute("user_session", user);
            return user;
        }else {
            return null;
        }                
}

后台搭建结束

6.前台搭建

<form>
 <input name="loginname" type="text"  id="loginname"/ >
 <input name="password" type="password" id="password"/>
 <input value="登录" style="width: 100%;" type="button" onclick="requestJson()" >
</form>

ajax异步登陆

<script type="text/javascript">
function requestJson(){
        var name =$("#loginname").val();//#是id选择器
            var pwd =$("#password").val();
            if(name==""){
                alert("用户名不能为空！");
                return false;
            }
            else if(pwd==" "){
                alert("密码不能为空！");
                return false;
            }
            else
            {
            $.ajax({
                type:'post',
                url:'checklogin',
                dataType:"json",//注意使用的是打他dataType，而不是Content-Type
                async: true,
                data:{loginname:name,paasword:pwd},
                success:function(data){
                   if(data==null){
                       alert("没有这个用户！")
                   }
                   else{
                       alert("登录成功")
                       window.location.href ="main";
                   }
                }
            });
           }
       }
   </script>