SpringBoot入门(十)

SpringBoot使用ServletAPI和拦截器

1、如何去使用ServletAPI：

1. package com.boot.servlet.api.bootservlet.servlet;
   
2. import javax.servlet.ServletException;
   
3. import javax.servlet.annotation.WebServlet;
   
4. import javax.servlet.http.HttpServlet;
   
5. import javax.servlet.http.HttpServletRequest;
   
6. import javax.servlet.http.HttpServletResponse;
   
7. import java.io.IOException;
   
8. @WebServlet(name = "MyServlet",urlPatterns = "/my")
   
9. public class MyServlet extends HttpServlet {
   
10.    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    
11.        System.out.println("执行了servlet的请求");
    
12.    }
    
13.    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    
14.      doPost(request,response);
    
15.    }
    
16. }
    

1.1、在创建一个Filter的类，代码如下:

1. package com.boot.servlet.api.bootservlet.filter;
   
2. import javax.servlet.*;
   
3. import javax.servlet.annotation.WebFilter;
   
4. import java.io.IOException;
   
5. @WebFilter(filterName = "MyFilter",urlPatterns = "/*")
   
6. public class MyFilter implements Filter {
   
7.    public void destroy() {
   
8.    }
   
9.    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
   
10.        System.out.println("执行了Filter");
    
11.        chain.doFilter(req, resp);
    
12.    }
    
13.    public void init(FilterConfig config) throws ServletException {
    
14.    }
    
15. }
    

1.2、创建了一个Listener的类，代码如下：

1. package com.boot.servlet.api.bootservlet.filter;
   
2. package com.boot.servlet.api.bootservlet.listener;
   
3. import javax.servlet.ServletContextEvent;
   
4. import javax.servlet.ServletContextListener;
   
5. import javax.servlet.annotation.WebListener;
   
6. @WebListener

   
7. public class MyListener implements ServletContextListener{
   
8.    public MyListener() {
   
9.    }
   
10.    public void contextInitialized(ServletContextEvent sce) {
    
11.        System.out.println("servlet容器启动");
    
12.    }
    
13.    @Override
    
14.    public void contextDestroyed(ServletContextEvent servletContextEvent) {
    
15.        System.out.println("servlet容器销毁");
    
16.    }
    
17. }
    

上面的配置是使用的注解的方式来配置的。

在SpringBoot如何去使用ServletAPI呢？

第一种方式：使用注解的方式：@ServletComponentScan去启动。使用这个注解的条件必须是servlet和listener还有filter的类上必须有带有注解的才可以。

代码如下：

1. package com.boot.servlet.api.bootservlet.filter;
   
2. package com.boot.servlet.api.bootservlet;
   
3. import org.springframework.boot.SpringApplication;
   
4. import org.springframework.boot.autoconfigure.SpringBootApplication;
   
5. import org.springframework.boot.web.servlet.ServletComponentScan;
   
6. @SpringBootApplication
   
7. @ServletComponentScan
   
8. public class BootServletApplication {
   
9.    public static void main(String[] args) {
   
10.        SpringApplication.run(BootServletApplication.class, args);
    
11.    }
    
12. }
    

然后启动下boot项目：输出的就是监听器监听到的。

去请求下MyServlet,这时的servlet的Api就引入成功了。

第二种方式：通过配置类的方式来配置，代码如下：

1. package com.boot.servlet.api.bootservlet.config;
   
2. import com.boot.servlet.api.bootservlet.filter.MyFilter;
   
3. import com.boot.servlet.api.bootservlet.listener.MyListener;
   
4. import com.boot.servlet.api.bootservlet.servlet.MyServlet;
   
5. import org.springframework.boot.SpringBootConfiguration;
   
6. import org.springframework.boot.web.servlet.FilterRegistrationBean;
   
7. import org.springframework.boot.web.servlet.ServletListenerRegistrationBean;
   
8. import org.springframework.boot.web.servlet.ServletRegistrationBean;
   
9. import org.springframework.context.annotation.Bean;
   
10. import java.util.Arrays;
    
11. @SpringBootConfiguration
    
12. public class ServletConfiguration {
    
13.    @Bean
    
14.    public ServletRegistrationBean<MyServlet>  registrationBean(){
    
15.        ServletRegistrationBean<MyServlet> bean=new ServletRegistrationBean<>(new MyServlet(),"/my");
    
16.        return bean;
    
17.    }
    
18.    @Bean
    
19.    public FilterRegistrationBean<MyFilter> filterFilterRegistrationBean(){
    
20.        FilterRegistrationBean<MyFilter> bean=new FilterRegistrationBean<>();
    
21.        bean.setFilter(new MyFilter());
    
22.        bean.setUrlPatterns(Arrays.asList("/*"));
    
23.        return bean;
    
24.    }
    
25.    @Bean
    
26.    public ServletListenerRegistrationBean<MyListener> servletListenerRegistrationBean(){
    
27.        ServletListenerRegistrationBean<MyListener> listener=new ServletListenerRegistrationBean<>();
    
28.        listener.setListener(new MyListener());
    
29.        return listener;
    
30.    }
    
31. }
    

启动项目运行下：这时也被监听到。

再次访问下：

这时过滤器和servlet的请求也都打印了出来。

上面就是引入servletAPI的方式。

2、如何在springBoot中使用拦截器：

代码如下：

2.1、写一个拦截器去实现HandlerInterceptor：

1. package com.boot.servlet.api.bootservlet.interceptor;
   
2. import org.springframework.web.servlet.HandlerInterceptor;
   
3. import org.springframework.web.servlet.ModelAndView;
   
4. import javax.servlet.http.HttpServletRequest;
   
5. import javax.servlet.http.HttpServletResponse;
   
6. public class MyInterceptor implements HandlerInterceptor {
   
7.    @Override
   
8.    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
   
9.        return true;
   
10.    }
    
11.    @Override
    
12.    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
    
13.        System.out.println("postHandle");
    
14.    }
    
15.    @Override
    
16.    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
    
17.        System.out.println("afterCompletion");
    
18.    }
    
19. }
    

2.2、写一个配置类来注册拦截器，代码如下：

1. package com.boot.servlet.api.bootservlet.config;
   
2. import com.boot.servlet.api.bootservlet.interceptor.MyInterceptor;
   
3. import org.springframework.boot.SpringBootConfiguration;
   
4. import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
   
5. import org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport;
   
6. @SpringBootConfiguration
   
7. public class MyWebMvcConfiguration extends WebMvcConfigurationSupport {
   
8.    @Override
   
9.    protected void addInterceptors(InterceptorRegistry registry) {
   
10.        registry.addInterceptor(new MyInterceptor());
    
11.    }
    
12. }
    

2.3、拦截器主要拦截的是controller,所以新建个controller,代码如下：

1. package com.boot.servlet.api.bootservlet.controller;
   
2. 
   
3. import org.springframework.stereotype.Controller;
   
4. import org.springframework.web.bind.annotation.GetMapping;
   
5. 
   
6. @Controller
   
7. public class TestController {
   
8.    @GetMapping("/index")
   
9.    public void index(){
   
10. 
    
11.    }
    
12. }
    

2.4、启动下项目并访问：这时就会拦截请求了。

总结：上面就是如何使用Servlet的API以及拦截器