springMVC 拦截器

@Controller
public class AdminController {

    @Inject
    private AdminService adminService;
    
    @RequestMapping(value="/",method=RequestMethod.GET)
    public String index() {
        
        return "index";
    }
    
    @RequestMapping(value="/",method=RequestMethod.POST)
    public String login(Admin admin,HttpSession session,RedirectAttributes redirectAttributes) {
        
        
        Admin currAdmin = adminService.login(admin.getName(),admin.getPassword());
        if(currAdmin == null) {
            redirectAttributes.addFlashAttribute("message", "账号或密码错误");
            // 重定向 
            return "redirect:/";
        } else {
            session.setAttribute("curr_admin", currAdmin);
            return "redirect:/book";
        }
    }
    
}

写一个类,继承HandlerInterceptorAdapter,并重写preHandle方法

public class LoginInterceptor extends HandlerInterceptorAdapter{
    
    private List<String> execludeUrls;
    
    
    @Override
    public boolean preHandle(HttpServletRequest request,
            HttpServletResponse response, Object handler) throws Exception {
        
        String url = request.getRequestURI();
        
        if(execludeUrls.contains(url) || url.startsWith("/static")) {
            return true;
        } else {
        
            HttpSession session = request.getSession();
            Admin admin = (Admin) session.getAttribute("curr_admin");
            
            if(admin == null) {
                System.out.println("未登录用户访问，访问被拒绝");
                //response.sendRedirect("/");
                /*在这里如果选择抛出异常,需要自定义一个异常,并且在mvc-servlet.xml中配置异常 */
                throw new LoginException();
            } 
            return true;
        }
    }

    // set注入 
    public void setExecludeUrls(List<String> execludeUrls) {
        this.execludeUrls = execludeUrls;
    }

}

 自定义异常 

package com.kaishengit.exception;

public class LoginException extends RuntimeException{

    
    private static final long serialVersionUID = 1L;

}

且在mvc-servlet.xml中配置

1.异常处理

<bean class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
        <property name="exceptionMappings">
            <props>
                <!-- 这里的异常处理选择重定向 -->
                <prop key="com.kaishengit.exception.LoginException">redirect:/</prop>
            </props>
        </property>
    </bean>

2.拦截器配置

<mvc:interceptors>
        
        <mvc:interceptor>
            <!-- 所有都要经过拦截器 -->
            <mvc:mapping path="/**"/>
            <bean class="com.kaishengit.controller.interceptor.LoginInterceptor">
                <!-- 在这里配置了一个叫execludeUrls的property,里面包含了三个请求路径
                    在LoginInterceptor里注入了execludeUrls(定义这个属性,并生成set方法),所以可以写execludeUrls.contains(url),就不用在
                    程序中写死了,如果不这样写,就还用老方法
                    "".equals(url) || "/".equals(url) || "/login".equals(url)-->
                <property name="execludeUrls">
                    <list>
                        <value></value>
                        <value>/</value>
                        <value>/login</value>
                    </list>
                </property>
            </bean>
        </mvc:interceptor>
    
    </mvc:interceptors>