Spring Boot——五、整合Web技术

SpringBoot项目整合的Web技术：
Servlet
Linstener
Filter
忘了里面的使用过程和重难点。javaee项目实战遇见的问题，用了这三个技术解决。是根源！整个过完一遍项目后回顾。

一个简单的springboot项目

package com.bjsxt.springbootweb2;

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

@SpringBootApplication
@ServletComponentScan
public class Springbootweb2Application {

    public static void main(String[] args) {
        SpringApplication.run(Springbootweb2Application.class, args);
        //System.exit(0);
    }

}

application.properties

server.port=8089

整合Servlet

package com.bjsxt.springbootweb2.servlet;

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

/**
 * /firstServlet
 * firstServlet
 * firstServlet
 * FirstServlet.class
 * service
 */
@WebServlet(name = "firstServlet",urlPatterns = "/firstServlet")
public class FirstServlet extends HttpServlet {
    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        PrintWriter writer = resp.getWriter();
        writer.write("firstServlet\n");
        writer.write("firstServlet\n");
        writer.write("firstServlet");
        writer.flush();
    }
}

运行结果：

整合Filter
代码：

package com.bjsxt.springbootweb2.filter;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;
import java.io.PrintWriter;

@WebFilter(urlPatterns = "/firstServlet")
public class FirstFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println("filter init");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        filterChain.doFilter(servletRequest,servletResponse);
        PrintWriter writer = servletResponse.getWriter();
        writer.write("\nfirstFilter");
        writer.flush();
    }

    @Override
    public void destroy() {
        System.out.println("filter destroy");
    }
}

运行结果：
在一个service方法后面增加了数据

整合Listener
代码：

package com.bjsxt.springbootweb2.listener;

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

@WebListener
public class FirstListener implements ServletContextListener {
    @Override
    public void contextInitialized(ServletContextEvent sce) {
        System.out.println("ServletContext already init");
        ServletContext servletContext = sce.getServletContext();
        System.out.println(servletContext);
    }

    @Override
    public void contextDestroyed(ServletContextEvent sce) {
        System.out.println("ServletContext already destroyed");
        ServletContext servletContext = sce.getServletContext();
        System.out.println(servletContext);
    }
}

运行结果：

启动类中的启动方法增加一句
System.exit(0);
运行结果：

总结：
web技术使用，需要在springboot的启动类上面增加一个@ServletComponentScan,扫描有@WebFilter,@WebServlet,@WebListener注解的类并且初始化！过滤器和Servlet类前面的注解里需要增加浏览器输入的uri参数，指明处理的是哪一个请求！