Spring Boot 监听器 过滤器 Servlet 实例

Listener Filter Servlet的执行顺序通常为： 监听器、过滤器、servlet

@RestController中的主Servlet都是DispatcherServlet，其默认的url-pattern为“/”。也可以自己添加Servlet，有2种方式：1）代码实现方式； 2）注解方式

代码实现方式： 通过ServletRegistrationBean、FilterRegistrationBean、ServletListenerRegistrationBean实现

实例：

package com.test.conf;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.context.embedded.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import com.test.servlet.TestServletByCode;

@Configuration
public class ServletRegistrationConf {
@Autowired
private TestServletByCode testServletByCode;
@Bean
    public ServletRegistrationBean servletRegistrationBean() {
        return new ServletRegistrationBean(testServletByCode, "/ts/testCodeServlet");
    }
}

package com.test.servlet;

import java.io.IOException;

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

import org.springframework.stereotype.Service;

@Service
public class TestServletByCode extends HttpServlet{
private static final long serialVersionUID = -8685285401859800066L;


    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("doGet====");
        doPost(req, resp);
    }


    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("doPost===");
    }
}

注解方式： 在 SpringBootApplication 上使用@ServletComponentScan 注解，Servlet、Filter、Listener 可以直接通过 @WebServlet、@WebFilter、@WebListener 注解自动注册

实例：

package com.test;

import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;


@SpringBootApplication
@ServletComponentScan
public class MainApplication implements CommandLineRunner {

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

@Override
public void run(String... args) throws Exception {
System.out.println("spring boot running........");
}
}

package com.test.listener;

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


@WebListener
public class TestServletContextListener implements ServletContextListener{
@Override
    public void contextInitialized(ServletContextEvent sce) {
        System.out.println("ServletContex初始化");
        System.out.println(sce.getServletContext().getServerInfo());
    }


    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        System.out.println("ServletContex销毁");
    }
}

package com.test.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;

@WebFilter(urlPatterns="/*",filterName="testFilter")
public class TestFilterByAnnotation implements Filter {
@Override
    public void destroy() {
        System.out.println("过滤器销毁");
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
        System.out.println("执行过滤操作");
        chain.doFilter(request, response);
    }

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

package com.test.servlet;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


@WebServlet(urlPatterns="/ts/testWebServlet", description="Servlet的说明")
public class TestServletByAnnotation extends HttpServlet{

    private static final long serialVersionUID = -8685285401859800066L;

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("doGet*******");
        doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        System.out.println("doPost*********");
    }

}

注：@ServletComponentScan在1.3版以后才有，需添加对应版本，如：

org.springframework.boot
spring-boot-starter-web
1.4.0.RELEASE