(20)Spring Boot Servlet【从零开始学Spring Boot】
Web开发使用 Controller 基本上可以完成大部分需求,但是我们还可能会用到 Servlet、Filter、Listener、Interceptor 等等。
当使用Spring-Boot时,嵌入式Servlet容器通过扫描注解的方式注册Servlet、Filter和Servlet规范的所有监听器(如HttpSessionListener监听器)。
Spring boot 的主 Servlet 为 DispatcherServlet,其默认的url-pattern为“/”。也许我们在应用中还需要定义更多的Servlet,该如何使用SpringBoot来完成呢?
在spring boot中添加自己的Servlet有两种方法,代码注册Servlet和注解自动注册(Filter和Listener也是如此)。
一、代码注册通过ServletRegistrationBean、 FilterRegistrationBean 和 ServletListenerRegistrationBean 获得控制。
也可以通过实现 ServletContextInitializer 接口直接注册。
二、在 SpringBootApplication 上使用@ServletComponentScan注解后,Servlet、Filter、Listener 可以直接通过 @WebServlet、@WebFilter、@WebListener 注解自动注册,无需其他代码。
这里我们新建一个spring-boot-hello2 java工程进行测试;这里不过多进行说明,如果这个还不会的话,请回到上上上一章进行查看。
通过代码注册Servlet示例代码:
package com.kfit.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
*
* @author Angel(QQ:412887952)
* @version v.0.1
*/
//这个不需要添加.
//@WebServlet(urlPatterns="/myServlet1/*", description="Servlet的说明")
publicclass MyServlet1 extends HttpServlet{
privatestaticfinallongserialVersionUID = 1L;
@Override
protectedvoid doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println(">>>>>>>>>>doGet()<<<<<<<<<<<");
doPost(req, resp);
}
@Override
protectedvoid doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println(">>>>>>>>>>doPost()<<<<<<<<<<<");
resp.setContentType("text/html");
PrintWriter out = resp.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<title>Hello World</title>");
out.println("</head>");
out.println("<body>");
out.println("<h1>这是:MyServlet1</h1>");
out.println("</body>");
out.println("</html>");
}
}
package com.kfit;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.embedded.ServletRegistrationBean;
import org.springframework.boot.web.servlet.ServletComponentScan;
import org.springframework.context.annotation.Bean;
import com.kfit.servlet.MyServlet1;
/**
*
*
* 大家也许会看到有些demo使用了3个注解: @Configuration;
*
* @EnableAutoConfiguration
* @ComponentScan
*
* 其实:@SpringBootApplication申明让spring boot自动给程序进行必要的配置,
*
* 等价于以默认属性使用@Configuration,
* @EnableAutoConfiguration和@ComponentScan
*
* 所以大家不要被一些文档误导了,让自己很迷茫了,希望本文章对您有所启发;
*
* @author Angel(QQ:412887952)
* @version v.0.1
*/
@SpringBootApplication
public class App {
/**
* 注册Servlet.不需要添加注解:@ServletComponentScan
* @return
*/
@Bean
public ServletRegistrationBean MyServlet1(){
return new ServletRegistrationBean(new MyServlet1(),"/myServlet/*");
}
public static void main(String[] args) {
SpringApplication.run(App.class, args);
}
}
右键Run As Java Application进行访问http://127.0.0.1:8080/myServlet1
使用注解注册Servlet示例代码
com.kfit.servlet.MyServlet2.java
package com.kfit.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
*
* @author Angel(QQ:412887952)
* @version v.0.1
*/
@WebServlet(urlPatterns="/myServlet2/*", description="Servlet的说明")
public class MyServlet2 extends HttpServlet{
private static final long serialVersionUID = 1L;
@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()<<<<<<<<<<<");
resp.setContentType("text/html");
PrintWriter out = resp.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<title>Hello World</title>");
out.println("</head>");
out.println("<body>");
out.println("<h1>这是:myServlet2</h1>");
out.println("</body>");
out.println("</html>");
}
}
SpringBootSampleApplication.java
package com.kfit;
import org.springboot.sample.servlet.MyServlet;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.embedded.ServletRegistrationBean;
import org.springframework.boot.web.servlet.ServletComponentScan;
import org.springframework.context.annotation.Bean;
import org.springframework.web.servlet.DispatcherServlet;
@SpringBootApplication
@ServletComponentScan//这个就是扫描相应的Servlet包;
public class SpringBootSampleApplication {
public static void main(String[] args) {
SpringApplication.run(SpringBootSampleApplication.class, args);
}
}