SpringBoot基础24_SpringBoot快速入门2

一、实现步骤分析

 1、创建Maven工程

 2、添加SpringBoot的起步依赖

 3、编写SpringBoot引导类

 4、编写Controller

 5、测试

二、代码实现

 1、创建Maven工程

  先创建一个空项目,然后使用idea工具创建一个maven工程,该module为普通的java工程即可

     

    

 2、添加SpringBoot的起步依赖

  SpringBoot要求,项目要继承SpringBoot的起步依赖spring-boot-starter-parent

  SpringBoot要集成SpringMVC进行Controller的开发,所以项目要导入web的启动依赖

<?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>

  <!--所有的springboot工程都必须继承spring-boot-start-parent--> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.0.1.RELEASE</version> </parent> <groupId>com.itheima</groupId> <artifactId>springboot_quick</artifactId> <version>1.0-SNAPSHOT</version> <dependencies> <!--web功能的起步依赖--> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> </dependencies> </project>

 3、编写SpringBoot引导类

  要通过SpringBoot提供的引导类起步SpringBoot才可以进行访问

package com.itheima;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

//声明该类是一个SpringBoot引导类 @SpringBootApplication
public class MySpringBootApplication { public static void main(String[] args) {
     //run方法 表示运行SpringBoot的引导类 run参数就是SpringBoot引导类的字节码对象 SpringApplication.run(MySpringBootApplication.
class); } }

 4、编写Controller

  在引导类MySpringBootApplication同级包或者子级包中创建QuickStartController

package com.itheima.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class QuickStartController {

    @RequestMapping("/quick")
    @ResponseBody
    public String quick(){
        return "hello springboot";
    }

}

 5、测试

  执行SpringBoot起步类的主方法,控制台打印日志如下:

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.0.1.RELEASE)

2024-03-26 15:22:48.688  INFO 4492 --- [           main] com.itheima.MySpringBootApplication      : Starting MySpringBootApplication on LAPTOP-VEKHRDDR with PID 4492 (C:\workFiles\javaLearn\code\SpringBoot\springboot_quick\target\classes started by ajing in C:\workFiles\javaLearn\code\SpringBoot)
2024-03-26 15:22:48.692  INFO 4492 --- [           main] com.itheima.MySpringBootApplication      : No active profile set, falling back to default profiles: default
2024-03-26 15:22:48.742  INFO 4492 --- [           main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@5906ebcb: startup date [Tue Mar 26 15:22:48 CST 2024]; root of context hierarchy
2024-03-26 15:22:49.789  INFO 4492 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2024-03-26 15:22:49.815  INFO 4492 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2024-03-26 15:22:49.815  INFO 4492 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.29
2024-03-26 15:22:49.820  INFO 4492 --- [ost-startStop-1] o.a.catalina.core.AprLifecycleListener   : The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [C:\software\Java\jdk1.8.0_251\bin;C:\Windows\Sun\Java\bin;C:\Windows\system32;C:\Windows;C:\software\Java\jdk1.8.0_251\bin;C:\software\Anaconda3;C:\software\Anaconda3\Library\mingw-w64\bin;C:\software\Anaconda3\Library\usr\bin;C:\software\Anaconda3\Library\bin;C:\software\Anaconda3\Scripts;C:\Program Files (x86)\Common Files\NetSarang;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\iCLS\;C:\Program Files\Intel\Intel(R) Management Engine Components\iCLS\;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Windows\System32\OpenSSH\;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files\Intel\Intel(R) Management Engine Components\IPT;C:\software\apache-jmeter-3.1\bin;C:\strawberry\c\bin;C:\strawberry\perl\bin;C:\Program Files\Intel\WiFi\bin\;C:\Program Files\Common Files\Intel\WirelessCommon\;C:\software\MySQL Server 5.5\bin;C:\software\apache-maven-3.5.2\bin;C:\Program Files\Git\cmd;C:\Program Files\TortoiseGit\bin;C:\Users\ajing\AppData\Local\Microsoft\WindowsApps;C:\Program Files\Intel\WiFi\bin\;C:\Program Files\Common Files\Intel\WirelessCommon\;.]
2024-03-26 15:22:49.938  INFO 4492 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2024-03-26 15:22:49.938  INFO 4492 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 1196 ms
2024-03-26 15:22:50.065  INFO 4492 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Servlet dispatcherServlet mapped to [/]
2024-03-26 15:22:50.070  INFO 4492 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
2024-03-26 15:22:50.070  INFO 4492 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2024-03-26 15:22:50.070  INFO 4492 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2024-03-26 15:22:50.070  INFO 4492 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]
2024-03-26 15:22:50.158  INFO 4492 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2024-03-26 15:22:50.339  INFO 4492 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@5906ebcb: startup date [Tue Mar 26 15:22:48 CST 2024]; root of context hierarchy
2024-03-26 15:22:50.382  INFO 4492 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
2024-03-26 15:22:50.383  INFO 4492 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
2024-03-26 15:22:50.399  INFO 4492 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2024-03-26 15:22:50.399  INFO 4492 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2024-03-26 15:22:50.505  INFO 4492 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2024-03-26 15:22:50.536  INFO 4492 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2024-03-26 15:22:50.539  INFO 4492 --- [           main] com.itheima.MySpringBootApplication      : Started MySpringBootApplication in 2.177 seconds (JVM running for 3.031)

  通过日志发现,Tomcat started on port(s): 8080 (http) with context path ''

  tomcat已经起步,端口监听8080,web应用的虚拟工程名称为空

  打开浏览器访问url地址为:http://localhost:8080/quick 

   

三、快速入门解析

 1、SpringBoot代码解析

  • @SpringBootApplication:标注SpringBoot的启动类,该注解具备多种功能(后面详细剖析)
  • SpringApplication.run(MySpringBootApplication.class) 代表运行SpringBoot的启动类,参数为SpringBoot启动类的字节码对象

 2、 SpringBoot工程热部署

  我们在开发中反复修改类、页面等资源,每次修改后都是需要重新启动才生效,这样每次启动都很麻烦,浪费了大量的时间,我们可以在修改代码后不重启就能生效,在 pom.xml 中添加如下配置就可以实现这样的功能,我们称之为热部署。

        <dependency>
            <!--热部署配置-->
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>

  注意:IDEA进行SpringBoot热部署失败原因

  出现这种情况,并不是热部署配置问题,其根本原因是因为Intellij IEDA默认情况下不会自动编译,需要对IDEA进行自动编译的设置,如下:

    

   然后 Shift+Ctrl+Alt+/,选择Registry

   

四、使用idea快速创建SpringBoot项目

     

 

   

 通过idea快速创建的SpringBoot项目的pom.xml中已经导入了我们选择的web的起步依赖的坐标(手动修改了spring-boot-starter-parent和java版本)

  注意:有可能在自动配置的过程中没有配置项目所需的相关依赖,这时就必须进行手动配置。

  

<?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 https://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>2.0.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.itheima</groupId>
    <artifactId>springboot_quick2</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot_quick2</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

   自动生成了SpringbootQuick2Application引导类

package com.itheima;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class SpringbootQuick2Application {

    public static void main(String[] args) {
        SpringApplication.run(SpringbootQuick2Application.class, args);
    }

}

  可以使用快速入门的方式创建Controller进行访问,此处不再赘述

  编写Controller类QuickController

package com.itheima.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController //包含了Controller和ResponseBody注解
public class QuickController {

    @RequestMapping("/quick2")
    public String quick(){
        return "springboot !!";
    }

}

  启动项目,执行SpringbootQuick2Application中main方法

  如出现报错信息:Error:(3, 29) java: 程序包org.junit.jupiter.api不存在,那么就需要手动配置

  浏览器访问http://localhost:8080/quick2,打印成功

   

 

posted on 2024-03-26 13:54  花溪月影  阅读(7)  评论(0编辑  收藏  举报