08-springmvc学习总结(拦截器)

案例：使用拦截器实现用户登陆认证

JavaBean对象(User.java)：

package com.zm.bean;

public class User {
    private String username;
    private String password;

    public User() {
    }

    public User(String username, String password) {
        this.username = username;
        this.password = password;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "User{" +
                "username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

创建拦截器：实现HandlerInterceptor接口

package com.zm.interceptor;

import com.zm.bean.User;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class LoginInterceptor implements HandlerInterceptor {


    /*在处理业务之前被调用*/
    @Override
    public boolean preHandle(HttpServletRequest req, HttpServletResponse resp, Object obj) throws Exception {
       System.out.println("preHandle……");
        String uri = req.getRequestURI();

        if(uri.indexOf("login")>0){//如果是访问登陆页面的请求，放行
            return true;
        }

        HttpSession session = req.getSession();
        User user = (User)session.getAttribute("user");
        if(user!=null){//登陆成功
            return true;
        }

        resp.sendRedirect("/login");
        return false;

    }

    /*在业务处理器处理请求完成之后、视图生成之前执行*/
    @Override
    public void postHandle(HttpServletRequest req, HttpServletResponse resp, Object o, ModelAndView mav) throws Exception {
        System.out.println("postHandle……");
    }

    /*在前端控制器完全处理完请求之后被调用，用于清理资源*/
    @Override
    public void afterCompletion(HttpServletRequest req, HttpServletResponse resp, Object obj, Exception ex) throws Exception {
        System.out.println("afterCompletion……");
    }
}

在spring mvc配置文件中注册拦截器

 <!--注册拦截器-->
    <mvc:interceptors>
   <!-- 可以注册多个拦截器-->
   
        <mvc:interceptor>
            <mvc:mapping path="/**"/>
            <!--在拦截器中配置需要放行的资源文件路径
               lib/js/jquery-3.3.1.js
            -->
            <mvc:exclude-mapping path="/lib/**" />
            <bean class="com.zm.interceptor.LoginInterceptor"></bean>
        </mvc:interceptor>
    </mvc:interceptors>
  

controller层(UserLoginController )：

package com.zm.controller;

import com.zm.bean.User;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

/*使用拦截器实现用户登陆验证的controller*/
@Controller
public class UserLoginController {
    /*访问User用户登陆页面*/
    @RequestMapping(value = "/login",method = RequestMethod.GET)
    public String loginUserForm(){
        return "loginUser";
    }

    /*访问用户登陆成功后要跳转的页面*/
    @RequestMapping(value = "/okUser",method = RequestMethod.GET)
    public String loginSuccess(){
        return "success";
    }

    /*接收从jsp页面提交过来的表单数据*/
    @RequestMapping(value = "/loginUser",method = RequestMethod.POST)
    public String login(User user,HttpServletRequest req){
        HttpSession session = req.getSession();
        if("admin".equals(user.getUsername())&&"123".equals(user.getPassword())){
            System.out.println("登陆成功，保存session……");
            session.setAttribute("user",user);
            return "redirect:/okUser";
        }else{
            System.out.println("登陆失败!");
            return "/login";
        }
    }

}

web页面
登陆页面(loginUser.jsp)：

<form method="post" action="loginUser">
    <p>
        用户名：<input type="text" name="username">
    </p>
    <p>
        密&ensp;&nbsp;码：<input type="password" name="password">
    </p>
    <p>
        <input type="submit" value="登陆">
        <input type="reset" value="取消">
    </p>
</form>

登陆成功后跳转的页面(success.jsp)：

<h3>success!welcime:${user.username}</h3>

来源：CSDN

作者：zmt0104

链接：https://blog.csdn.net/qq_40845019/article/details/100046036