springboot 启动类_《SpringBoot入门》

SpringBoot介绍
1. 什么是Spring Boot？

Spring Boot是由Pivotal团队提供的全新框架，其设计目的是用来简化新Spring应用的初始搭建以及开发过程。该框架使用了特定的方式来进行配置，从而使开发人员不再需要定义样板化的配置。通过这种方式，Spring Boot致力于在蓬勃发展的快速应用开发领域(rapid application development)成为领导者。

Spring Boot有哪些特点？

构建SpringBoot项目以及启动器讲解
1. Spring Boot常见的启动器有哪些？

spring-boot-starter-web是web的启动器，可以为全栈式的开发提供支持，包含tomcat、springmvc等jar包

spring-boot-starter-jdbc:支持spring以jdbc方式操作数据库的jar包的集合

spring-boot-starter-redis:支持redis键值存储的数据库操作

Spring Boot的Web启动器的坐标是什么？

<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<version>2.1.9.RELEASE</version>
</dependency>

编写HelloWorld
1. 如何编写Spring Boot启动类？

package com.bjsxt.startapp;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication(scanBasePackages = "com.bjsxt")
public class StartForTestListener2 {
public static void main(String[] args) {
SpringApplication.run(StartForTestListener2.class,args);
}
}

编写Spring Boot启动类时需要注意什么？

启动器存放的位置。启动器可以和 controller 位于同一个包下，或者位于 controller 的上一级包中，但是不能放到 controller 的平级以及子包下。

Spring Boot整合Servlet
1. Spring Boot整合Servlet有几种方式？

两种

各种方式有什么特点？

1.注解方式：

Servlet类：

package com.bjsxt.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;
@WebServlet(name = "FirstServlet",urlPatterns = "/first")
public class FirstServlet extends HttpServlet {
@Override
public void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("first servlet");
}
}

启动类：

package com.bjsxt.startapp;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
@SpringBootApplication(scanBasePackages = "com.bjsxt")
@ServletComponentScan(basePackages = "com.bjsxt.servlet")
public class StartApplication {
public static void main(String[] args) {
SpringApplication.run(StartApplication.class, args);
}
}

配置类方式：

1.servlet类：
package com.bjsxt.servlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class SecondServlet extends HttpServlet {
@Override
public void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("second servlet");
}
}
2.配置类：
package com.bjsxt.config;
import com.bjsxt.servlet.SecondServlet;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class ServletConfiguration {
@Bean
public ServletRegistrationBean getServletRegistrationBean(){
ServletRegistrationBean bean=new ServletRegistrationBean(new SecondServlet());
bean.addUrlMappings("/second");//相当于设置url-pattern
return bean;
}
}
启动类：
package com.bjsxt.startapp;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication(scanBasePackages = "com.bjsxt")
public class StartApplication2 {
public static void main(String[] args) {
SpringApplication.run(StartApplication2.class, args);
}
}

Spring Boot整合Filter
1. Spring Boot整合Filter有几种方式？

两种：

注解方式
配置类方式
1. 各种方式有什么特点？

1.注解方式：

Filter类：

package com.bjsxt.filter;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;
@WebFilter(filterName = "FirstFilter",urlPatterns ="/first")
public class FirstFilter implements Filter {
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
System.out.println("进入Filter");
filterChain.doFilter(servletRequest, servletResponse);
System.out.println("离开Filter");
}
}

启动类：

package com.bjsxt.startapp;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
@SpringBootApplication(scanBasePackages = "com.bjsxt")
@ServletComponentScan("com.bjsxt.filter")
public class StartForTestFilter1 {
public static void main(String[] args) {
SpringApplication.run(StartForTestFilter1.class,args);
}
}

2.配置类方式：

Filter类：

package com.bjsxt.filter;
import javax.servlet.*;
import java.io.IOException;
public class SecondFilter implements Filter {
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
System.out.println("进入Filter2");
filterChain.doFilter(servletRequest, servletResponse);
System.out.println("离开Filter2");
}
}

配置类：

package com.bjsxt.config;
import com.bjsxt.servlet.SecondServlet;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class ServletConfiguration {
@Bean
public ServletRegistrationBean getServletRegistrationBean(){
ServletRegistrationBean bean=new ServletRegistrationBean(new SecondServlet());
bean.addUrlMappings("/second");
return bean;
}
}

启动类：

package com.bjsxt.startapp;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication(scanBasePackages = "com.bjsxt")
public class StartForTestFilter2 {
public static void main(String[] args) {
SpringApplication.run(StartForTestFilter2.class,args);
}
}

springBoot整合Listener
1. Spring Boot整合Listener有几种方式？

两种 :注解方式和配置类方式

各种方式有什么特点？

1.注解：

Listener类：

package com.bjsxt.listener;
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("listener初始化");
}
@Override
public void contextDestroyed(ServletContextEvent sce) {
}
}

启动类：

package com.bjsxt.startapp;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
@SpringBootApplication(scanBasePackages = "com.bjsxt")
@ServletComponentScan("com.bjsxt.listener")
public class StartForTestListener1 {
public static void main(String[] args) {
SpringApplication.run(StartForTestListener1.class,args);
}
}

方式二：配置类

1.Listener类：
package com.bjsxt.listener;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;
public class SecondListener implements ServletContextListener {
@Override
public void contextInitialized(ServletContextEvent sce) {
System.out.println("listener2初始化");
}
@Override
public void contextDestroyed(ServletContextEvent sce) {
}
}
2.配置类：
package com.bjsxt.config;//package com.bjsxt.config;
import com.bjsxt.listener.SecondListener;
import org.springframework.boot.web.servlet.ServletListenerRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class ListenerConfiguration {
@Bean
public ServletListenerRegistrationBean<SecondListener> getServletListenerRegistrationBean(){
return new ServletListenerRegistrationBean(new SecondListener());
}
}
3.启动类：
package com.bjsxt.startapp;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
@SpringBootApplication(scanBasePackages = "com.bjsxt")
public class StartForTestListener2 {
public static void main(String[] args) {
SpringApplication.run(StartForTestListener2.class,args);
}
}