springboot中使用拦截器和servlet-摩杜云开发者社区

拦截器是SpringMVC中一种对象，能拦截器对Controller的请求。

拦截器框架中有系统的拦截器，还可以自定义拦截器。实现对请求预先处理。

2. springmvc实现自定义拦截器： 29

2.1 创建类实现SpringMVC框架的HandlerInterceptor接口

public interface HandlerInterceptor {
    default boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        return true;
    }

    default void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable ModelAndView modelAndView) throws Exception {
    }

    default void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable Exception ex) throws Exception {
    }
}

2.2 需在SpringMVC的配置文件中，声明拦截器

<mvc:interceptors>
	<mvc:interceptor>
    	<mvc:path="url" />
        <bean class="拦截器类全限定名称"/>
    </mvc:interceptor>
</mvc:interceptors>

3. springboot实现拦截器 30-31

需求，拦截登录请求

自定义拦截器LoginInterceptor

package com.bjpowernode.web;

import org.springframework.web.servlet.HandlerInterceptor;

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

/**
 * springboot自定义拦截器  30
 */
public class LoginInterceptor implements HandlerInterceptor  {

    /**
     *
     * @param request
     * @param response
     * @param handler  被拦截器的控制器对象
     * @return boolean
     *    true： 请求能被Controller处理
     *    false: 请求被截断
     */
    @Override
    public boolean preHandle(HttpServletRequest request,
                             HttpServletResponse response,
                             Object handler) throws Exception {
        System.out.println("执行了LoginInterceptor的preHandle");
        return true;
    }
}

注册自定义拦截器MyAppConfig

package com.bjpowernode.config;

import com.bjpowernode.web.LoginInterceptor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

//注册拦截器  30
//springboot自定义拦截器  30
@Configuration //这个类当作xml文件使用
public class MyAppConfig implements WebMvcConfigurer {

    //添加拦截器对象， 注入到容器中
    @Override
    public void addInterceptors(InterceptorRegistry registry) {

        //创建拦截器对象
        LoginInterceptor interceptor = new LoginInterceptor();

        //指定拦截的请求uri地址
        String path []= {"/user/**"};
        //指定不拦截的地址
        String excludePath  [] = {"/user/login"};
        registry.addInterceptor(interceptor)//将我们自定义的拦截器添加进InterceptorRegistry
                .addPathPatterns(path)//这个是拦截谁
                .excludePathPatterns(excludePath);//这个是不拦截谁

    }
}

控制器类BootController

package com.bjpowernode.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

//springboot自定义拦截器  31
@Controller
public class BootController {

    @RequestMapping("/user/account")
    @ResponseBody
    public String userAccount(){
        return "访问user/account地址";
    }

    @RequestMapping("/user/login")
    @ResponseBody
    public String userLogin(){
        return "访问user/login地址";
    }
}

测试Course6Application

package com.bjpowernode;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Course6Application {

    public static void main(String[] args) {
        SpringApplication.run(Course6Application.class, args);
    }

}

浏览器访问http://localhost:8080/user/account

拦截器执行

springboot中使用拦截器和servlet

浏览器访问http://localhost:8080/user/login

拦截器不执行

4. 使用servlet 32

ServletRegistrationBean 用来做在 servlet 3.0+容器中注册 servlet 的功能，但更具有

SpringBean 友好性。

在SpringBoot框架中使用Servlet对象。

4.1 使用步骤：

1. 创建Servlet类。创建类继承HttpServlet

2. 注册Servlet ，让框架能找到Servlet

4.2 例子：32-33

代码在course6_1中

1.创建自定义Servlet

MyServlet

package com.bjpowernode.web;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

//springboot使用servlet  32
//创建Servlet类
public class MyServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req,resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
       //使用HttpServletResponse输出数据，应答结果
        resp.setContentType("text/html;charset=utf-8");
        PrintWriter out  = resp.getWriter();
        out.println("===执行的是Servlet==");
        out.flush();
        out.close();

    }
}

注册Servlet

WebApplictionConfig

package com.bjpowernode.config;

import com.bjpowernode.web.MyServlet;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class WebApplictionConfig {

    //定义方法， 注册Servlet对象
    @Bean
    public ServletRegistrationBean servletRegistrationBean(){

        //有参构造
        //第一个参数是 Servlet对象， 第二个是url地址
        //public ServletRegistrationBean(T servlet, String... urlMappings)

//        ServletRegistrationBean bean =
//                      new ServletRegistrationBean( new MyServlet(),"/myservlet");


        //无参构造  33
        ServletRegistrationBean bean = new ServletRegistrationBean();
        bean.setServlet( new MyServlet());
        bean.addUrlMappings("/login","/test"); // 


        return bean;
    }
}

springboot中使用拦截器和servlet