1. Servlet

1.1 自定义Servlet

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

/**
 * Created by HuangJun
 * 9:42 2018/11/9
 */
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 {
        resp.setContentType("text/html;charset=utf-8");
        resp.getWriter().write("This is MyServlet");
    }
}

1.2 注册Servlet

在上文创建的 WebConfig 类中添加如下代码：

 @Bean
    public ServletRegistrationBean servletRegistrationBean() {
        return new ServletRegistrationBean(new MyServlet(),"/myServlet");
    }

1.3 运行结果

打开浏览器，访问 http://localhost:8080/test/myServlet，结果如下图：

2. Filter

2.1 自定义过滤器

import javax.servlet.*;
import java.io.IOException;

/**
 * Created by HuangJun
 * 10:02 2018/11/9
 */
public class TimeFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println("=======初始化过滤器=========");
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain)
            throws IOException, ServletException {
        long start = System.currentTimeMillis();
        filterChain.doFilter(request, response);
        System.out.println("filter 耗时：" + (System.currentTimeMillis() - start));

    }

    @Override
    public void destroy() {
        System.out.println("=======销毁过滤器=========");
    }

}

2.2 注册过滤器

在上文创建的 WebConfig 类中添加如下代码：

@Bean
public FilterRegistrationBean timeFilter() {
     FilterRegistrationBean registrationBean = new FilterRegistrationBean();
     TimeFilter timeFilter = new TimeFilter();
     registrationBean.setFilter(timeFilter);
     List<String> urls = new ArrayList<>();
     urls.add("/*");
     registrationBean.setUrlPatterns(urls);
     return registrationBean;
 }

2.3 运行结果

打开浏览器，访问 http://localhost:8080/test/myServlet，观察控制台打印输出，结果如下图：

3. Listener

3.1 自定义Listener

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

/**
 * Created by HuangJun
 * 10:28 2018/11/9
 */
public class MyListener implements ServletContextListener {
    @Override
    public void contextInitialized(ServletContextEvent sce) {
        System.out.println("监听器初始化...");
    }

    @Override
    public void contextDestroyed(ServletContextEvent sce) {

    }
}

3.2 注册Listener

在上文创建的 WebConfig 类中添加如下代码：

@Bean
public ServletListenerRegistrationBean<MyListener> servletListenerRegistrationBean() {
    return new ServletListenerRegistrationBean<MyListener>(new MyListener());
}

3.3 运行结果

观察控制台打印输出，结果如下图

自定义 Servlet、Filter 和 Listener 的另一种配置方式，修改引导类，代码如下：

import com.springboot.web.filter.TimeFilter;
import com.springboot.web.listener.MyListener;
import com.springboot.web.servlet.MyServlet;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletContextInitializer;

import javax.servlet.DispatcherType;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import java.util.EnumSet;

@SpringBootApplication
public class WebApplication implements ServletContextInitializer {

    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        // 配置 Servlet
        servletContext.addServlet("servletTest",new MyServlet())
                .addMapping("/myServlet");
        // 配置过滤器
        servletContext.addFilter("timeFilter",new TimeFilter())
                .addMappingForUrlPatterns(EnumSet.of(DispatcherType.REQUEST),true,"/*");
        // 配置监听器
        servletContext.addListener(new MyListener());
    }
    public static void main(String[] args) {
        SpringApplication.run(WebApplication.class, args);
    }
}

4. 源码下载

源码下载地址:https://download.****.net/download/huangjun0210/10774393