SpringBoot

Posted 2022-06-04 mxj961116

1.Demo

（1）pom.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0        
　　　　　　　　　　　　　　　　　http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.21.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    
    <groupId>com.mxj</groupId>
    <artifactId>01-springboot-hello</artifactId>
    <version>1.0-SNAPSHOT</version>

    <!--修改jdk版本-->
    <properties>
        <java.version>1.8</java.version>
    </properties>

    <!--springboot启动器-->
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>

</project>    

（2）配置Controller

@Controller
public class Helloworld 
    @RequestMapping("/hello")
    @ResponseBody
    public Map<String,Object> showHelloWorld()
        Map<String,Object> map = new HashMap<>();
        map.put("msg","HelloWorld");
        return map;
    

（3）编写启动器

注意：启动器存放的位置可以和Controller位于同一个包下，或者位于Controller的上一级包中，但是不能放在Controller的平级以及子包下

/**
 * SpringBoot 启动类
 */
@SpringBootApplication
public class App 

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

 2.SpringBoot整合Servlet

（1）通过注解扫描完成Servlet组件的注册

编写Servlet

@WebServlet(name="FirstServlet",urlPatterns="/first")
public class FirstServlet extends HttpServlet 
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException 
        super.doGet(req, resp);
    

编写启动类

@SpringBootApplication
@ServletComponentScan   //在springBoot启动时会扫描@WebServlet,并将该类实例化
public class App 
    public static void main(String[] args)
        SpringApplication.run(App.class,args);
    

（2）通过方法完成Servlet组件的注册

编写Servlet

public class SecondServlet extends HttpServlet 
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException 
        System.out.println("SecondServlet..............");
    

编写启动类

@SpringBootApplication
public class App2 
    public static void main(String[] args)
        SpringApplication.run(App2.class,args);
    

    @Bean
    public ServletRegistrationBean getServletRegistrationBean()
        ServletRegistrationBean bean = new ServletRegistrationBean(new SecondServlet());
        bean.addUrlMappings("/second");
        return bean;