学习日志：SpringBoot--Servlet三大组件以及WEB

servlet三大组件配置

1.编写servlet

//编写好后在配置类中注册
public class Myservlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.getWriter().println("hello， my big baby");
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req,resp);
    }
}

2.编写Filter

public class MyFilter implements Filter {
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        System.out.println("my wonderful filter");
        filterChain.doFilter(servletRequest,servletResponse);
    }
}

3.编写Listener

public class Mylistenner implements ServletContextListener {
    @Override
    public void contextInitialized(ServletContextEvent sce) {
        System.out.println("My wonderful Listener。。。Initialized");
    }
    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        System.out.println("Listener。。。Destroyed");
    }
}

4.在配置文件中注册

//编写配置类定制嵌入式servlet容器相关规则servlet相关配置
    @Bean
    public WebServerFactoryCustomizer<ConfigurableWebServerFactory> webServerFactoryCustomizer(){
        return new WebServerFactoryCustomizer<ConfigurableWebServerFactory>() {
            @Override
            public void customize(ConfigurableWebServerFactory factory) {
                factory.setPort(8888);
            }
        };
    }
    //注册三大组件
    @Bean
    //注册servlet
    public ServletRegistrationBean myservlet(){
        ServletRegistrationBean servletRegistrationBean = new ServletRegistrationBean(new Myservlet(), "/Myservlet");
        return servletRegistrationBean;
    }
    //注册filter
    @Bean
    public FilterRegistrationBean myfilter(){
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
        filterRegistrationBean.setFilter(new MyFilter());
        filterRegistrationBean.setUrlPatterns(Arrays.asList("/Myservlet"));
        return filterRegistrationBean;
    }
    //注册listener
    @Bean
    public ServletListenerRegistrationBean mylistener(){
        ServletListenerRegistrationBean<Mylistenner> mylistennerServletListenerRegistrationBean = new ServletListenerRegistrationBean<>(new Mylistenner());
        return mylistennerServletListenerRegistrationBean;
    }

5.引入web模块时就默认使用嵌入式tomcat容器，但不支持JSP。然而开发是需要JSP，则需要手动引入外部的tomcat

#使用外置的tomcat容器
1.将项目的打包方式改为war
2.(系统会自动生产，但是这个类必须有)编写一个类继承

SpringBootServletInitializer，并重写configure方法，调用参数的sources方法springboot启动类传过去然后返回
public class ServletInitializer extends SpringBootServletInitializer {
    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(HelloSpringBootWebApplication.class);
    }

}
3.（设置后系统会自动加上，没有就需要手动加）然后把tomcat的依赖范围改为provided

<dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <version>2.2.1.RELEASE</version>
            <scope>provided</scope>
        </dependency>

4.最后就可以把项目打包成war放到tomcat中了并创建web.xml

5.在IDEA中Run中设置tomcat