hello world的深意，Spring boot (1)--- 第一个应用程序helloworld

1. File -->new-->maven project  创建项目。项目工程如下：

hello world的深意，

2： pom 文件如下：

<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>
  <groupId>com.zyzx.sample</groupId>
  <artifactId>ch1.helloworld</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  
   <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.0.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

Springboot启动流程，    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <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>

hello world 资源？    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

3. 创建 Ch1Application

package com.zyzx.sample.ch1类

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

@SpringBootApplication
public class Ch1Application {
    public static void main(String[] args) {
    
        SpringApplication.run(Ch1Application.class, args);
    }

}

4. 创建controller 类

package com.zyzx.sample.ch1.controller;

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

@Controller
public class HelloWorldController {
    
    @RequestMapping("/say.html")
    
    public @ResponseBody String say() {
        return "hello spring boot!";
        
    }

}
@controller 是SpringMVC的注解，表示此类用于负责处理web的请求。

@RequestMapping 是SpringMVC的注解，表示如果请求路径匹配，被注解的方法将被被调用。

@ResponseBody 表示返回的是文本，而不是视图名称

运行程序：.   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.0.0.RELEASE)

2018-11-03 22:26:15.049  INFO 9292 --- [           main] com.zyzx.sample.ch1.Ch1Application       : Starting Ch1Application on CC4 with PID 9292 (D:\eclipse-workspace-ee\ch1.helloworld\target\classes started by zhangbijun in D:\eclipse-workspace-ee\ch1.helloworld)
2018-11-03 22:26:15.054  INFO 9292 --- [           main] com.zyzx.sample.ch1.Ch1Application       : No active profile set, falling back to default profiles: default
2018-11-03 22:26:15.141  INFO 9292 --- [           main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@4c40b76e: startup date [Sat Nov 03 22:26:15 CST 2018]; root of context hierarchy
2018-11-03 22:26:16.996  INFO 9292 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2018-11-03 22:26:17.035  INFO 9292 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2018-11-03 22:26:17.036  INFO 9292 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.28
2018-11-03 22:26:17.051  INFO 9292 --- [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:\Program Files\Java\jre1.8.0_181\bin;C:\Windows\Sun\Java\bin;C:\Windows\system32;C:\Windows;C:/Program Files/Java/jre1.8.0_181/bin/server;C:/Program Files/Java/jre1.8.0_181/bin;C:/Program Files/Java/jre1.8.0_181/lib/amd64;C:\Program Files (x86)\Common Files\Oracle\Java\javapath;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\Intel\OpenCL SDK\3.0\bin\x86;C:\Program Files (x86)\Intel\OpenCL SDK\3.0\bin\x64;C:\Program Files\Intel\WiFi\bin\;C:\Program Files\Common Files\Intel\WirelessCommon\;C:\Program Files\Java\jdk1.8.0_181\bin;C:\Program Files\Java\jdk1.8.0_181\jre\bin;C:\Program Files\Intel\WiFi\bin\;C:\Program Files\Common Files\Intel\WirelessCommon\;C:\adb;D:\spring_boot\apache-maven-3.5.4/bin;D:\nodejs\;C:\Program Files\Intel\WiFi\bin\;C:\Program Files\Common Files\Intel\WirelessCommon\;C:\Users\Administrator\AppData\Roaming\npm;C:\Users\Administrator\Desktop;;.]
2018-11-03 22:26:17.216  INFO 9292 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2018-11-03 22:26:17.216  INFO 9292 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 2078 ms
2018-11-03 22:26:17.380  INFO 9292 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Servlet dispatcherServlet mapped to [/]
2018-11-03 22:26:17.385  INFO 9292 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
2018-11-03 22:26:17.385  INFO 9292 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2018-11-03 22:26:17.385  INFO 9292 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2018-11-03 22:26:17.385  INFO 9292 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]
2018-11-03 22:26:17.786  INFO 9292 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@4c40b76e: startup date [Sat Nov 03 22:26:15 CST 2018]; root of context hierarchy
2018-11-03 22:26:17.877  INFO 9292 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/say.html]}" onto public java.lang.String com.zyzx.sample.ch1.controller.HelloWorldController.say()
2018-11-03 22:26:17.886  INFO 9292 --- [           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)
2018-11-03 22:26:17.887  INFO 9292 --- [           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)
2018-11-03 22:26:17.926  INFO 9292 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-11-03 22:26:17.926  INFO 9292 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-11-03 22:26:17.970  INFO 9292 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-11-03 22:26:18.148  INFO 9292 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2018-11-03 22:26:18.239  INFO 9292 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2018-11-03 22:26:18.244  INFO 9292 --- [           main] com.zyzx.sample.ch1.Ch1Application       : Started Ch1Application in 3.627 seconds (JVM running for 4.218)
2018-11-03 22:28:29.662  INFO 9292 --- [nio-8080-exec-2] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring FrameworkServlet 'dispatcherServlet'
2018-11-03 22:28:29.662  INFO 9292 --- [nio-8080-exec-2] o.s.web.servlet.DispatcherServlet        : FrameworkServlet 'dispatcherServlet': initialization started
2018-11-03 22:28:29.681  INFO 9292 --- [nio-8080-exec-2] o.s.web.servlet.DispatcherServlet        : FrameworkServlet 'dispatcherServlet': initialization completed in 19 ms

5.打开浏览器 ，输入 http://localhost:8080/say.html