使用spring boot 在MyEclipse上创建一个简单的应用程序
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特点
1. 创建独立的Spring应用程序
2. 嵌入的Tomcat，无需部署WAR文件
3. 简化Maven配置
4. 自动配置Spring
5. 提供生产就绪型功能，如指标，健康检查和外部配置
6. 绝对没有代码生成和对XML没有要求配置
环境准备：
Myeclipse
jdk1.7及以上
maven 3.0以上
1、首先建一个maven项目，pom.xml文件内容如下代码所示：
<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/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>cn.cpt</groupId> <artifactId>SpringBoot</artifactId> <version>0.0.1-SNAPSHOT</version> <name>SpringBoot Maven Webapp</name> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.2.5.RELEASE</version> <relativePath /> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <java.version>1.8</java.version> </properties> <dependencies> <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> </project>
2、保存之后静静等待依赖包下载完毕，接下来创建一个java类，
在src/main/java下创建一个TestSpringBoot.java类，里面添加代码如下：
package controller;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
@SpringBootApplication
@RestController
public class TestSpringBoot {
@RequestMapping("/")
public String firstSpringBoot() {
return "Hello World!";
}
public static void main(String[] args){
SpringApplication.run(TestSpringBoot.class, args);
}
}
3、直接运行main方法；它会启动内置的tomcat服务：启动后如下所示：
. ____ _ __ _ _ /\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \ ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \ \\/ ___)| |_)| | | | | || (_| | ) ) ) ) ' |____| .__|_| |_|_| |_\__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot :: (v1.2.5.RELEASE) 2018-01-17 16:20:06.722 INFO 6028 --- [ main] controller.TestSpringBoot : Starting TestSpringBoot on 0DYF9DI9DPNWES6 with PID 6028 (started by Administrator in D:\Softwarefolder\IDE\MyEclipse\WorkSpace\SSM\SpringBoot Maven Webapp) 2018-01-17 16:20:06.831 INFO 6028 --- [ main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@5fd91a7a: startup date [Wed Jan 17 16:20:06 CST 2018]; root of context hierarchy 2018-01-17 16:20:08.077 INFO 6028 --- [ 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]] 2018-01-17 16:20:09.743 INFO 6028 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 9000 (http) 2018-01-17 16:20:10.247 INFO 6028 --- [ main] o.apache.catalina.core.StandardService : Starting service Tomcat 2018-01-17 16:20:10.249 INFO 6028 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.0.23 2018-01-17 16:20:10.485 INFO 6028 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext 2018-01-17 16:20:10.485 INFO 6028 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 3659 ms 2018-01-17 16:20:11.820 INFO 6028 --- [ost-startStop-1] o.s.b.c.e.ServletRegistrationBean : Mapping servlet: 'dispatcherServlet' to [/] 2018-01-17 16:20:11.827 INFO 6028 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*] 2018-01-17 16:20:11.827 INFO 6028 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*] 2018-01-17 16:20:12.187 INFO 6028 --- [ main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@5fd91a7a: startup date [Wed Jan 17 16:20:06 CST 2018]; root of context hierarchy 2018-01-17 16:20:12.343 INFO 6028 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/]}" onto public java.lang.String controller.TestSpringBoot.firstSpringBoot() 2018-01-17 16:20:12.344 INFO 6028 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/login],methods=[GET]}" onto public java.lang.String controller.TestSpringBoot.loginGet() 2018-01-17 16:20:12.344 INFO 6028 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/login],methods=[POST]}" onto public java.lang.String controller.TestSpringBoot.loginPost() 2018-01-17 16:20:12.348 INFO 6028 --- [ 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.BasicErrorController.error(javax.servlet.http.HttpServletRequest) 2018-01-17 16:20:12.348 INFO 6028 --- [ 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.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest) 2018-01-17 16:20:12.407 INFO 6028 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2018-01-17 16:20:12.407 INFO 6028 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2018-01-17 16:20:12.482 INFO 6028 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler] 2018-01-17 16:20:12.619 INFO 6028 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup 2018-01-17 16:20:12.747 INFO 6028 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 9000 (http) 2018-01-17 16:20:12.750 INFO 6028 --- [ main] controller.TestSpringBoot : Started TestSpringBoot in 6.666 seconds (JVM running for 7.24)
3、在网页上可输入地址localhost:8080/即可访问到firstSpringBoot()方法，在页面上显示Hello word,
（如果报错端口被占用的话可以修改内置Tomcat的端口，详情连接 http://www.cnblogs.com/caopt/p/8303662.html）
4、这是一个简单应用程序，可是为什么它运行main方法就可以了呢，让我们从源码分析一下：
运行main方法之后 SpringApplication会运行他的run方法，看下源码
/**
* Static helper that can be used to run a {@link SpringApplication} from the
* specified source using default settings.
* @param source the source to load
* @param args the application arguments (usually passed from a Java main method)
* @return the running {@link ApplicationContext}
*/
public static ConfigurableApplicationContext run(Object source, String... args) {
return run(new Object[] { source }, args);
}
/**
* Static helper that can be used to run a {@link SpringApplication} from the
* specified sources using default settings and user supplied arguments.
* @param sources the sources to load
* @param args the application arguments (usually passed from a Java main method)
* @return the running {@link ApplicationContext}
*/
public static ConfigurableApplicationContext run(Object[] sources, String[] args) {
return new SpringApplication(sources).run(args);
}
1、它根据传过来的类会创建一个Spring应用上下文（Application Context）（通过映射的方式找到要找的东西）。另一方面它会扫描当前应用类路径上的依赖，例如本例中发现spring-webmvc（由 spring-boot-starter-web传递引入）在类路径中，那么Spring Boot会判断这是一个Web应用，并启动一个内嵌的Servlet容器（默认是Tomcat）用于处理HTTP请求。
2、当发生请求过来之后，Spring Web Mvc框架会将Servlet容器里收到的HTTP请求根据路径分发给对应的
@Controller类进行处理，@RestController是一类特殊的@Controller，它的返回值直接作为HTTP Response的Body部分返回给浏览器。 3、多个url路径如下代码
package controller;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;
@SpringBootApplication
@RestController
public class TestSpringBoot {
@RequestMapping(value = "/TestGet", method = RequestMethod.GET)
public String testGet() {
return "Hello Get";
}
@RequestMapping(value = "/TestPost", method = RequestMethod.POST)
public String testPost() {
return "Hello Post";
}
@RequestMapping("/")
public String firstSpringBoot() {
return "Hello World!";
}
public static void main(String[] args){
SpringApplication.run(TestSpringBoot.class, args);
}
}
4、springBoot对调试支持很好，修改之后可以实时生效，需要添加以下的配置：
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<optional>true</optional>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<configuration>
<fork>true</fork>
</configuration>
</plugin>
</plugins>
</build>
这里需要注意的是，版本要匹配不然会报错。
