第二十四章 springboot注入servlet，springbootservlet

第二十四章 springboot注入servlet，springbootservlet

問：有了springMVC，為什麼還要用servlet？有了servlet3的註解，為什麼還要使用ServletRegistrationBean注入的方式？

使用情境：在有些情境下，比如我們要使用hystrix-dashboard，這時候就需要注入HystrixMetricsStreamServlet（第三方的servlet），該servlet是hystrix的組件。

一、代碼

1、TestServlet（第一個servlet）

1 package com.xxx.secondboot.servlet; 2 3 import java.io.IOException; 4 5 import javax.servlet.ServletException; 6 import javax.servlet.http.HttpServlet; 7 import javax.servlet.http.HttpServletRequest; 8 import javax.servlet.http.HttpServletResponse; 9 10 public class TestServlet extends HttpServlet {11 12 private static final long serialVersionUID = -4619665430596950563L;13 14 @Override15 protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {16 System.out.println("zhaojigang servlet");17 }18 19 @Override20 protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {21 this.doGet(req, resp);22 }23 }View Code

2、Testservlet2（第二個servlet）

1 package com.xxx.secondboot.servlet; 2 3 import java.io.IOException; 4 5 import javax.servlet.ServletException; 6 import javax.servlet.http.HttpServlet; 7 import javax.servlet.http.HttpServletRequest; 8 import javax.servlet.http.HttpServletResponse; 9 10 public class TestServlet2 extends HttpServlet {11 12 private static final long serialVersionUID = 3788279972938793265L;13 14 @Override15 protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {16 System.out.println("zhaojigang servlet2");17 }18 19 @Override20 protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {21 this.doGet(req, resp);22 }23 }View Code

3、ServletConfig（servlet注入配置類）

 1 package com.xxx.secondboot.servlet; 2  3 import org.springframework.boot.context.embedded.ServletRegistrationBean; 4 import org.springframework.context.annotation.Bean; 5 import org.springframework.context.annotation.Configuration; 6  7 @Configuration 8 public class ServletConfig { 9     10     @Bean11     public TestServlet testServlet(){12         return new TestServlet();13     }14     15     @Bean16     public ServletRegistrationBean testServletRegistrationBean(TestServlet testServlet){17         ServletRegistrationBean registration = new ServletRegistrationBean(testServlet);18         registration.setEnabled(true);19         registration.addUrlMappings("/servlet/test");20         return registration;21     }22     /********************************************/23     @Bean24     public TestServlet2 testServlet2(){25         return new TestServlet2();26     }27     28     @Bean29     public ServletRegistrationBean test2ServletRegistrationBean(TestServlet2 testServlet2){30         ServletRegistrationBean registration = new ServletRegistrationBean(testServlet2);31         registration.setEnabled(true);32         registration.addUrlMappings("/servlet/test2");33         return registration;34     }35     36 }

說明：使用ServletRegistrationBean來注入servlet，對於每一個servlet都有一個ServletRegistrationBean來注入。

注意：如果只是自己要使用servlet，可以直接只用servlet3的註解來聲明servlet就好，但是像HystrixMetricsStreamServlet這樣的第三方servlet，就只能通過上邊這樣的方式來搞了。

 

二、測試

啟動服務，瀏覽器輸入"http://localhost:8083/servlet/test","http://localhost:8083/servlet/test2"，查看console的輸出。