1. 程式人生 > >springboot自動以filter,interceptor,listener實現自定義過濾、攔截、監聽

springboot自動以filter,interceptor,listener實現自定義過濾、攔截、監聽

 

1:自定義攔截器

(1)實現Filter介面

(2)添加註解WebFilter,指定要過濾的路徑、指定filer的名字、指定初始化引數

 (3)新增@ServletComponentScan註解開啟掃描servlet元件

package top.lrshuai.fli.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 javax.servlet.annotation.WebFilter;


/**
 * 
 * 使用註解標註過濾器
 * @WebFilter將一個實現了javax.servlet.Filter介面的類定義為過濾器
 * 屬性filterName 宣告過濾器的名稱,可選
 * 屬性urlPatterns指定要過濾 的URL模式,這是一個數組引數,可以指定多個。也可使用屬性value來宣告.(指定要過濾的URL模式是必選屬性)
 */
@WebFilter(filterName="myFilter",urlPatterns={"/*"})
public class MyFilter implements Filter{

	@Override
	public void destroy() {
		System.out.println("myfilter 的 銷燬方法");
	}

	@Override
	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
			throws IOException, ServletException {
		System.out.println("myfilter 的 過濾方法。這裡可以執行過濾操作");
		//繼續下一個攔截器
		chain.doFilter(request, response);
	}

	@Override
	public void init(FilterConfig arg0) throws ServletException {
		System.out.println("myfilter 的 初始化方法");
	}

}

過濾器最先執行所有請求路徑是/*的請求。

2:自定義實現攔截器

(1)實現InterceptorHandler介面

  (2)  攔截器preHandler(controller之前執行)和postHandler(controller執行之後,檢視被渲染之前執行)方法和

afterCompletion(請求結束之後呼叫,也就是檢視渲染完成之後呼叫。主要用於資源清理工作)
package top.lrshuai.fli.interceptor;

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

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
/**
 * 可以驗證使用者是否登入來攔截,沒登陸返回false
 * @author tyro
 *
 */
public class LoginInterceptor implements HandlerInterceptor{

	@Override
	public void afterCompletion(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, Exception arg3)
			throws Exception {
		System.out.println("LoginInterceptor 在整個請求結束之後被呼叫,也就是在DispatcherServlet 渲染了對應的檢視之後執行(主要是用於進行資源清理工作)");
	}

	@Override
	public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, ModelAndView arg3)
			throws Exception {
		System.out.println("LoginInterceptor  請求處理之後進行呼叫,但是在檢視被渲染之前(Controller方法呼叫之後)");
	}

	@Override
	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object arg2) throws Exception {
		System.out.println("LoginInterceptor 在請求處理之前進行呼叫(Controller方法呼叫之前) 這裡是攔截的操作");
		String user = (String) request.getSession().getAttribute("user");
		System.out.println("user="+user);
		if(null == user || "".equals(user)){
			response.setContentType("text/html;charset=utf-8");
			response.getWriter().println("你沒登陸,請去登入頁面:<a href='http://localhost:8080/login'>登入</a>。");
			return false;
		}
		return true;
	}

}
package top.lrshuai.fli.interceptor;

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

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

public class MyInterceptor implements HandlerInterceptor{

	@Override
	public void afterCompletion(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, Exception arg3)
			throws Exception {
		System.out.println("MyInterceptor 在整個請求結束之後被呼叫,也就是在DispatcherServlet 渲染了對應的檢視之後執行(主要是用於進行資源清理工作)");
	}

	@Override
	public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, ModelAndView arg3)
			throws Exception {
		System.out.println("MyInterceptor  請求處理之後進行呼叫,但是在檢視被渲染之前(Controller方法呼叫之後)");		
	}

	@Override
	public boolean preHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2) throws Exception {
		System.out.println("MyInterceptor 在請求處理之前進行呼叫(Controller方法呼叫之前)這裡是攔截的操作");
		return true;
	}

}

定義完攔截器之後。要對攔截器進行註冊,才能使攔截器起到作用。實現

WebMvcConfigurerAdapter.重寫addInterceptors方法即可程式碼如下:指定攔截器攔截的請求和排除攔截的請求
package top.lrshuai.fli.interceptor;

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

@Configuration
public class WebConfigurer extends WebMvcConfigurerAdapter {

	@Override
	public void addInterceptors(InterceptorRegistry registry) {
		 // addPathPatterns 用於新增攔截規則
		// excludePathPatterns 排除攔截
		registry.addInterceptor(new LoginInterceptor()).addPathPatterns("/**").excludePathPatterns("/login");
		registry.addInterceptor(new MyInterceptor()).addPathPatterns("/**");
		super.addInterceptors(registry);
	}
}

(3)自定義監聽器:ServletContextListerner    HttpSessionListener。實現這兩個介面。並且新增@weblinstener註解指定其

為自定義web監聽器

package top.lrshuai.fli.listener;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;

@WebListener
public class ServletListener implements ServletContextListener{

	@Override
	public void contextDestroyed(ServletContextEvent arg0) {
		System.out.println("servlet 銷燬時呼叫");
	}

	@Override
	public void contextInitialized(ServletContextEvent arg0) {
		System.out.println("servlet 初始化時呼叫");
	}

}
@RequestMapping("/logout")
	public String logout(){
		System.out.println("這是在logout方法裡銷燬session試試");
		((ServletRequestAttributes) RequestContextHolder.getRequestAttributes())
		.getRequest().getSession().removeAttribute("user");
		((ServletRequestAttributes) RequestContextHolder.getRequestAttributes())
		.getRequest().getSession().invalidate();
		
		return "logout success";
	}
package top.lrshuai.fli.listener;

import javax.servlet.annotation.WebListener;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

@WebListener
public class SessionListener implements HttpSessionListener{

	@Override
	public void sessionCreated(HttpSessionEvent arg0) {
		System.out.println("監聽 建立session");
	}

	@Override
	public void sessionDestroyed(HttpSessionEvent arg0) {
		System.out.println("監聽 銷燬session");
	}

}

session銷燬後執行的對應監聽器的方法