电商模块开发-第二天

1.实现用户登录功能

//用户实体类
import java.util.Date;

public class User {
    private int id;
    private String loginName;
    private String password;
    private String name;
    private int sex;
    private String email;
    private String phone;
    private String address;
    private int role;
    private Date createDate;
    private int disabled;
    private String active;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getLoginName() {
        return loginName;
    }
    public void setLoginName(String loginName) {
        this.loginName = loginName;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getSex() {
        return sex;
    }
    public void setSex(int sex) {
        this.sex = sex;
    }
    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
    public String getPhone() {
        return phone;
    }
    public void setPhone(String phone) {
        this.phone = phone;
    }
    public String getAddress() {
        return address;
    }
    public void setAddress(String address) {
        this.address = address;
    }
    public int getRole() {
        return role;
    }
    public void setRole(int role) {
        this.role = role;
    }
    public Date getCreateDate() {
        return createDate;
    }
    public void setCreateDate(Date createDate) {
        this.createDate = createDate;
    }
    public int getDisabled() {
        return disabled;
    }
    public void setDisabled(int disabled) {
        this.disabled = disabled;
    }
    public String getActive() {
        return active;
    }
    public void setActive(String active) {
        this.active = active;
    }
}

//dao层
@Repository("userDao")
public interface UserDao {
    @Select("select * from ec_user where LOGIN_NAME=#{loginName}")
    public User selectByAccount(String loginName);
}

//业务层及其实现类
public interface UserService {
    public Map<String,Object> login(String account,String password);
}

@Service("userService")
public class UserServiceImp implements UserService {
    @Resource
    private UserDao userDao;
    @Override
    public Map<String, Object> login(String loginName, String password) {   // 与之前代码的不同之处，在于使用了Map来进行封装结果，能够将处理信息在页面上显示。
        Map<String,Object> map=new HashMap<>();
        User user=userDao.selectByAccount(loginName);
        if (StringUtils.isEmpty(loginName) || StringUtils.isEmpty(password) ){   //StringUtils类属于spring框架中的。
            map.put("code",2);
            map.put("msg","不能为空！");
        }else{
            if (user!=null){
                if (user.getPassword().equals(password)){
                    map.put("code",0);
                    map.put("msg",user);
                } else{
                    map.put("code",1);
                    map.put("msg","密码错误！");
                }
            }else{
                map.put("code",3);
                map.put("msg","用户不存在！");
            }
        }
        return map;
    }
}

//servlet请求处理
@WebServlet("/login")
public class LoginServlet extends HttpServlet {
     private HttpServletRequest request;
     private HttpServletResponse response;
     private UserService service1;
    @Override
    public void init() throws ServletException {
        super.init();
        ServletContext servletContext=this.getServletContext();
        WebApplicationContext context= WebApplicationContextUtils.getWebApplicationContext(servletContext);
        service1=(UserService)context.getBean("userService");
    }
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.request=req;                     //这里用到了this关键字，查看资料。
        this.response=resp;
        String param=request.getParameter("method");
        if(param.equals("getJsp")){
            req.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request,response);
        }else if(param.equals("login")){
            login();
        }
    }
    private void login() throws ServletException, IOException {
        String loginName=request.getParameter("loginName");
        String password=request.getParameter("passWord");
        Map<String,Object> map=service1.login(loginName,password);
        if ((int)map.get("code")==0){
            User user=(User)map.get("msg");
            request.getSession().setAttribute("USER",user);
        }else{
            String msg=map.get("msg")+"";   //+“”可将其转化为字符串。
            request.setAttribute("Msg",msg);
            request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request,response);
        }
    }
}

2.异常。

事件：过程中出现了空指针异常。

地点：在service的实现类中。

原因：少判断一种情况，数据库中不存在的用户进行登录时，导致user为null。没有对该情况进行处理。