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spring boot简单例子

程序员文章站 2022-04-09 09:14:06
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创建一个maven工程，对应的pom.xml文件：

 <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <!-- Spring Boot 启动父依赖 -->
<parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>1.2.4.RELEASE</version></parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding></properties> <dependencies>
  <!-- Spring Boot web依赖 -->
<dependency> <groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency> </dependencies> <build><plugins> <plugin> <groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId></plugin> </plugins> </build>
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SpringBoot应用部署到Tomcat下的配置方法用于tomcat版本问题的朋友


    

  1. 

    将打包方式改成war 
    

    2. 

  2. 

    配置嵌入Tomcat中的方式 
    
这里有两种方式可选择：
    

    方式一：用spring-boot内置的tomcat库，
并指定你要部署到Tomcat的版本
    

    <properties>
    <tomcat.version>7.0.69</tomcat.version>
</properties>
<dependency>
    <groupId>org.apache.tomcat</groupId>
    <artifactId>tomcat-juli</artifactId>
    <version>${tomcat.version}</version>
</dependency>
    

      

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    方式二：不用spring-boot内置的tomcat库（强烈推荐这种方式！！）
    

    <!-- 打war包时加入此项， 告诉spring-boot tomcat相关jar包用外部的，不要打进去 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-tomcat</artifactId>
    <scope>provided</scope>
</dependency>
    

    3. 

  3. 
在项目启动的时候报了一个 


    16:48
    

    www.baidu.com
    


    java.lang.NoClassDefFoundError:
java/nio/channels/AsynchronousChannelGroup
    
的错误，检查之后发现项目启动配置的jdk版本是1.6.0_18，换成1.7.0_72版本之后就没问题了
    

    4. 



版本采用1.2.4,非官网最新版，但属于稳定版本






创建一个启动类 Application.java



我们的main方法通过调用run，将业务委托给了spring
Boot的SpringApplication类。SpringApplication将引导我们的应用，启动Spring，相应地启动被自动配置的Tomcat web服务器。我们需要将 Example.class 作为参数传递给run方法来告诉SpringApplication谁是主要的Spring组件。为了暴露任何的命令行参数，args数组也会被传递过去。


package com.lkl.springboot;

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




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


    

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运行main方法



  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v1.2.4.RELEASE)

2015-08-25 22:53:35.484  INFO 554 --- [           main] com.lkl.springboot.Application       : Starting Application on mac.local with PID 554 (/Users/liaokailin/code/github/blog-springboot/target/classes started by lkl in /Users/liaokailin/code/github/blog-springboot)
2015-08-25 22:53:35.561  INFO 554 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot[email protected]328908cd: startup date [Tue Aug 25 22:53:35 CST 2015]; root of context hierarchy
2015-08-25 22:53:36.395  INFO 554 --- [           main] o.s.b.f.s.DefaultListableBeanFactory     : Overriding bean definition for bean 'beanNameViewResolver': replacing [Root bean: class [null]; scope=; abstract=false; lazyInit=false; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=org.springframework.boot.autoconfigure.web.ErrorMvcAutoConfiguration$WhitelabelErrorViewConfiguration; factoryMethodName=beanNameViewResolver; initMethodName=null; destroyMethodName=(inferred); defined in class path resource [org/springframework/boot/autoconfigure/web/ErrorMvcAutoConfiguration$WhitelabelErrorViewConfiguration.class]] with [Root bean: class [null]; scope=; abstract=false; lazyInit=false; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapter; factoryMethodName=beanNameViewResolver; initMethodName=null; destroyMethodName=(inferred); defined in class path resource [org/springframework/boot/autoconfigure/web/WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapter.class]]
2015-08-25 22:53:37.404  INFO 554 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http)
2015-08-25 22:53:37.796  INFO 554 --- [           main] o.apache.catalina.core.StandardService   : Starting service Tomcat
2015-08-25 22:53:37.798  INFO 554 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.0.23
2015-08-25 22:53:37.955  INFO 554 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2015-08-25 22:53:37.955  INFO 554 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 2397 ms
2015-08-25 22:53:38.813  INFO 554 --- [ost-startStop-1] o.s.b.c.e.ServletRegistrationBean        : Mapping servlet: 'dispatcherServlet' to [/]
2015-08-25 22:53:38.818  INFO 554 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean  : Mapping filter: 'characterEncodingFilter' to: [/*]
2015-08-25 22:53:38.819  INFO 554 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean  : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2015-08-25 22:53:39.075  INFO 554 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot[email protected]328908cd: startup date [Tue Aug 25 22:53:35 CST 2015]; root of context hierarchy
2015-08-25 22:53:39.151  INFO 554 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],methods=[],params=[],headers=[],consumes=[],produces=[],custom=[]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
2015-08-25 22:53:39.151  INFO 554 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],methods=[],params=[],headers=[],consumes=[],produces=[text/html],custom=[]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest)
2015-08-25 22:53:39.180  INFO 554 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2015-08-25 22:53:39.180  INFO 554 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2015-08-25 22:53:39.232  INFO 554 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2015-08-25 22:53:39.326  INFO 554 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2015-08-25 22:53:39.430  INFO 554 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8080 (http)
2015-08-25 22:53:39.433  INFO 554 --- [           main] com.lkl.springboot.Application       : Started Application in 4.829 seconds (JVM running for 5.238)



spring boot已经启动，内嵌tomcat容器，监听为8080端口


就是这么简单，一个spring boot 的程序就创建了。



@SpringBootApplication 注解


SpringBootApplication注解源码如下：


@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@Configuration
@EnableAutoConfiguration
@ComponentScan
public @interface SpringBootApplication {

    /**
     * Exclude specific auto-configuration classes such that they will never be applied.
     * @return the classes to exclude
     */
    Class<?>[] exclude() default {};

}


    

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@Configuration : 表示Application作为sprig配置文件存在 
@EnableAutoConfiguration: 启动spring boot内置的自动配置 
@ComponentScan : 扫描bean，路径为Application类所在package以及package下的子路径，这里为com.lkl.springboot，在spring boot中bean都放置在该路径已经子路径下。





构建REST工程


创建一个package：com.lkl.springboot.controller 保存controller


构建 HelloWorldController.java


 package com.lkl.springboot.controller;

import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/springboot")
public class HelloWorldController {

    @RequestMapping(value = "/{name}", method = RequestMethod.GET)
    public String sayWorld(@PathVariable("name") String name) {
        return "Hello " + name;
    }
}


    

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再次执行 Application 然后访问http://localhost:8080/springboot/zhangsan


得到结果： 
Hello zhangsan








					

																				

						

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