Spring boot三大器

在Spring boot 中的应用中的三大拦截机制 Filter 、Interceptor 、Aspect

1、Filter

Filter功能：可以拿到原始的http请求，但是拿不到你请求的控制器和请求控制器中的方法的信息

Filter使用：

package com.llangzh.filter;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

import org.springframework.stereotype.Component;

@Component
public class MyFilter implements Filter{

	@Override
	public void init(FilterConfig filterConfig) throws ServletException {
		System.out.println("myFilter init........");
	}

	@Override
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
			throws IOException, ServletException {
		System.out.println("执行任务前.................");
		chain.doFilter(request, response);
		System.out.println("执行任务后...........");
	}

	@Override
	public void destroy() {
		System.out.println("Myfilter destory........");
	}

}

测试：

。。。。。。。。。

myFilter init........

。。。。。。。。。

doFilter 执行任务前...........
任务执行...........
doFilter 执行任务后...........

2、Interceptor

Interceptor作用：可以拿到你请求的控制器和方法，却拿不到请求方法的参数

Interceptor用法：

（1）先在配置类中配置Interceptor

package com.llangzh.config;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

import com.llangzh.interceptor.MyInterceptor;

@Configuration
public class interceptorConfig extends WebMvcConfigurerAdapter{

	@Autowired
	private MyInterceptor myInterceptor;
	
	@Override
	public void addInterceptors(InterceptorRegistry registry) {
		
		registry.addInterceptor(myInterceptor);
	}
}

（2）使用Interceptor

package com.llangzh.interceptor;

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

import org.springframework.stereotype.Component;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

@Component
public class MyInterceptor implements HandlerInterceptor{

	@Override
	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
			throws Exception {
		System.out.println("preHandler..........");
		System.out.println(((HandlerMethod)handler).getBean().getClass().getName());
		
		request.setAttribute("abc", "abc");
		return true;
	}

	@Override
	public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
			ModelAndView modelAndView) throws Exception {
		System.out.println("postHandler...........");
		System.out.println(request.getAttribute("abc"));
	}

	@Override
	public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
			throws Exception {
		System.out.println("afterHandler..........");
		System.out.println("ex is" + ex);
	}
}

测试：

preHandler..........
com.llangzh.controller.UserController
任务执行...........
postHandler...........
abc
afterHandler..........
ex isnull

3、Aspect

aspect作用：可以拿到方法的参数，但是却拿不到http请求和响应的对象

aspect用法：

package com.llangzh.aspect;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.springframework.stereotype.Component;

@Aspect
@Component
public class MyAspect {

        //环绕方式
	@Around("execution(* com.llangzh.controller.UserController.*(..))")
	public Object handlerControllerMethod(ProceedingJoinPoint point) throws  Throwable {
		
		System.out.println("MyAspect start............");
		Object[] args = point.getArgs();
		
		for (Object arg : args) {
			System.out.println(arg);
		}

		Object proceed = point.proceed();
		
		System.out.println("MyAspect end............");
		return proceed;
	}
}

测试：

MyAspect start............
1
任务执行...........
MyAspect end............

当Filter、Interceptor、Aspect一起存在的时候，测试结果为：

doFilter 执行任务前...........
preHandler..........
com.llangzh.controller.UserController$$EnhancerBySpringCGLIB$$a43b51b8
MyAspect start............
1
任务执行...........
MyAspect end............
postHandler...........
abc
afterHandler..........
ex isnull
doFilter 执行任务后...........

可以看到拦截过程为：Filter——>Interceptor——>Aspect