拦截器完成权限控制

java里的拦截器是动态拦截Action调用的对象，它提供了一种机制可以使开发者在一个Action执行的前后执行一段代码，也可以在一个Action
执行前阻止其执行，同时也提供了一种可以提取Action中可重用部分代码的方式。在AOP中，拦截器用于在某个方法或者字段被访问之前，进行拦截
然后再之前或者之后加入某些操作。

• 第一步 定义注解

package com.alibaba.gov.kamala2.service.annotation;

import com.alibaba.gov.kamala2.enums.userrole.Kamala2LevelEnum;

import java.lang.annotation.*;

@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@documented
public @interface AclUrlAutoHandle {
    
    String name();
    
    String value() default "";
    
    String code();

    
    Kamala2LevelEnum level() default Kamala2LevelEnum.LOW;

    
    boolean nodeFlg() default false;

    
    String description() default "系统添加的权限";
}

• 第二步 定义拦截器类，该类实现HandlerInterceptor接口，并重写preHandle、postHandle、afterCompletion方法（如有需要）；此处只需要重写preHandler即可；

import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
 
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
@Component
public class MyInterceptor implements HandlerInterceptor {
 
 //注入上下文
	@Autowired
    private ApplicationContext applicationContext;
    
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception{
      RequestMappingHandlerMapping rmhp = applicationContext.getBean(RequestMappingHandlerMapping.class);
        Map map = rmhp.getHandlerMethods();
        for(RequestMappingInfo info : map.keySet()){
            HandlerMethod hm=map.get(info);
            Method method = hm.getMethod();
           Object o = method.getAnnotation(AclUrlAutoHandle.class);
            if(o!= null){
                System.out.println(info.getPatternsCondition());
            }
        }
        return true;
    }
 
    
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
                           ModelAndView modelAndView) throws Exception{
 
        System.out.println("解析视图之前.....");
    }
 
    
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler,
                      Exception ex) throws Exception{
        System.out.println("视图解析完成...");
    }
}

• 第三步：重写preHandler方法，在该方法体中获取含有自定义注解的url，并保存到set中；

@Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception{
      RequestMappingHandlerMapping rmhp = applicationContext.getBean(RequestMappingHandlerMapping.class);
       Set set = new HashSet<>();
        Map map = rmhp.getHandlerMethods();
        for(RequestMappingInfo info : map.keySet()){
            HandlerMethod hm=map.get(info);
            Method method = hm.getMethod();
           Object o = method.getAnnotation(AclUrlAutoHandle.class);
            if(o!= null){
                System.out.println(info.getPatternsCondition());
                set.add(info.getPatternsCondition().toString());
            }
        }
        return true;
    }

• 根据用户、角色、权限、授权记录四张表中的逻辑关系，来确定该用户是否有某一路径的权限（此处不做详细展开）