springboot注入servlet的方法

问：有了springmvc，为什么还要用servlet？有了servlet3的注解，为什么还要使用servletregistrationbean注入的方式？

使用场景：在有些场景下，比如我们要使用hystrix-dashboard，这时候就需要注入hystrixmetricsstreamservlet（第三方的servlet），该servlet是hystrix的组件。

一、代码

1、testservlet（第一个servlet）

package com.xxx.secondboot.servlet;

import java.io.ioexception;

import javax.servlet.servletexception;
import javax.servlet.http.httpservlet;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;

public class testservlet extends httpservlet {
  
  private static final long serialversionuid = -4619665430596950563l;

  @override
  protected void doget(httpservletrequest req, httpservletresponse resp) throws servletexception, ioexception {
    system.out.println("zhaojigang servlet");
  }

  @override
  protected void dopost(httpservletrequest req, httpservletresponse resp) throws servletexception, ioexception {
    this.doget(req, resp);
  }
}

2、testservlet2（第二个servlet）

package com.xxx.secondboot.servlet;

import java.io.ioexception;

import javax.servlet.servletexception;
import javax.servlet.http.httpservlet;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;

public class testservlet2 extends httpservlet {

  private static final long serialversionuid = 3788279972938793265l;

  @override
  protected void doget(httpservletrequest req, httpservletresponse resp) throws servletexception, ioexception {
    system.out.println("zhaojigang servlet2");
  }

  @override
  protected void dopost(httpservletrequest req, httpservletresponse resp) throws servletexception, ioexception {
    this.doget(req, resp);
  }
}

3、servletconfig（servlet注入配置类）

package com.xxx.secondboot.servlet;

import org.springframework.boot.context.embedded.servletregistrationbean;
import org.springframework.context.annotation.bean;
import org.springframework.context.annotation.configuration;

@configuration
public class servletconfig {
  
  @bean
  public testservlet testservlet(){
    return new testservlet();
  }
  
  @bean
  public servletregistrationbean testservletregistrationbean(testservlet testservlet){
    servletregistrationbean registration = new servletregistrationbean(testservlet);
    registration.setenabled(true);
    registration.addurlmappings("/servlet/test");
    return registration;
  }
  /********************************************/
  @bean
  public testservlet2 testservlet2(){
    return new testservlet2();
  }
  
  @bean
  public servletregistrationbean test2servletregistrationbean(testservlet2 testservlet2){
    servletregistrationbean registration = new servletregistrationbean(testservlet2);
    registration.setenabled(true);
    registration.addurlmappings("/servlet/test2");
    return registration;
  }
  
}

说明：使用servletregistrationbean来注入servlet，对于每一个servlet都有一个servletregistrationbean来注入。

注意：如果只是自己要使用servlet，可以直接只用servlet3的注解来声明servlet就好，但是像hystrixmetricsstreamservlet这样的第三方servlet，就只能通过上边这样的方式来搞了。

 二、测试

启动服务，浏览器输入"http://localhost:8083/servlet/test","http://localhost:8083/servlet/test2"，查看console的输出。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。