SpringBoot支持Servlet有两种方式 (文件上传)
第一种方式
1：代码注册通过ServletRegistrationBean获得控制
首先定义一个Servlet
DuckTestServlet

package com.duck.servlet;

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

public class DuckTestServlet extends HttpServlet{

    private static final long serialVersionUID = -8685285401859800066L;

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        // TODO Auto-generated method stub
        this.doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        // TODO Auto-generated method stub
        System.out.println("this is DuckTestServlet");
        PrintWriter pw = resp.getWriter();
        pw.write("this is DuckTestServlet");
        pw.flush();
        pw.close();
    }

    @Override
    public void init() throws ServletException {
        // TODO Auto-generated method stub
        super.init();
    }
}

2：
ServletRegistrationBean注册定义的Servlet

package com.duck;

import com.duck.servlet.DuckTestServlet;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;

@SpringBootApplication(scanBasePackages = {"com.duck"},exclude={})
public class DuckAdminApplication {

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

    /**
     * 通过代码的形式注册一个Servlet，这种形式不需要添加@ServletComponentScan注解来扫描
     * @return
     */
    @Bean
    public ServletRegistrationBean servletRegistrationBean() {
        return new ServletRegistrationBean(new DuckTestServlet(), "/duckTest/*");
    }

}

通过访问路径控制urlmapping,此为/duckTest/*，即可拦截到servlet方法

image.png

第二种方式
通过WebServlet方式
1：定义DuckTest2Servlet

package com.duck.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;

/**
 *  @WebServlet注解的Servlet注册需要@ServletComponentScan注解的扫描
 */
@WebServlet(urlPatterns = "/duckTest2/*")
public class DuckTest2Servlet extends HttpServlet{
    private static final long serialVersionUID = -8685285401859800067L;

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        // TODO Auto-generated method stub
        this.doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        System.out.println("this is DuckTest2Servlet");
        PrintWriter pw = resp.getWriter();
        pw.write("this is DuckTest2Servlet");
        pw.flush();
        pw.close();
    }

    @Override
    public void init() throws ServletException {
        // TODO Auto-generated method stub
        super.init();
    }
}

2：启动类添加@ServletComponentScan

package com.duck;

import com.duck.servlet.DuckTestServlet;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;

@SpringBootApplication(scanBasePackages = {"com.duck"},exclude={})
//扫描工程中的Servlet
@ServletComponentScan(basePackages = {"com.duck"})
public class DuckAdminApplication {

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

    /**
     * 通过代码的形式注册一个Servlet，这种形式不需要添加@ServletComponentScan注解来扫描
     * @return
     */
    @Bean
    public ServletRegistrationBean servletRegistrationBean() {
        return new ServletRegistrationBean(new DuckTestServlet(), "/duckTest/*");
    }

}

3：通过定义的urlmapping路径，即可进入servlet方法

image.png