SpringBoot 初识

2017-08-29

通过 IDEA 创建 SpringBoot 工程

本次选择的 SpringBoot 版本是1.5.9.RELEASE

打开 IDEA ，点击 File -> New -> Project -> Spring Initializr

选择Project SDK: JDK 1.8
选择Initializr Service URL: Default
点击 Next，等待一会，有时会提示 Initialization failed，重新尝试即可

修改Group、Artifact 即可，可以适当调整一下Package

添加起步依赖：Web starter 依赖

配置工程名称及工程存放路径

生成的项目目录结构

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.9.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>

<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>

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

默认的pom.xml 文件内主要内容：
parent 标签表示从 spring-boot-starter-parent 继承的版本号
properties 标签内定义编码格式，jdk 版本
dependencies 标签表示使用哪些起步依赖
build 标签表示使用哪些插件

SpringBoot Application 类

package com.example.springboot.hello;

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

@SpringBootApplication
public class SpringBootHelloApplication {

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

@SpringBootApplication 注解是一个组合注解

package org.springframework.boot.autoconfigure;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.springframework.boot.SpringBootConfiguration;
import org.springframework.boot.context.TypeExcludeFilter;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.FilterType;
import org.springframework.context.annotation.ComponentScan.Filter;
import org.springframework.core.annotation.AliasFor;

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(
    excludeFilters = {@Filter(
    type = FilterType.CUSTOM,
    classes = {TypeExcludeFilter.class}
), @Filter(
    type = FilterType.CUSTOM,
    classes = {AutoConfigurationExcludeFilter.class}
)}
)
public @interface SpringBootApplication {
    @AliasFor(
        annotation = EnableAutoConfiguration.class,
        attribute = "exclude"
    )
    Class<?>[] exclude() default {};

    @AliasFor(
        annotation = EnableAutoConfiguration.class,
        attribute = "excludeName"
    )
    String[] excludeName() default {};

    @AliasFor(
        annotation = ComponentScan.class,
        attribute = "basePackages"
    )
    String[] scanBasePackages() default {};

    @AliasFor(
        annotation = ComponentScan.class,
        attribute = "basePackageClasses"
    )
    Class<?>[] scanBasePackageClasses() default {};
}

其包含如下三个注解：
@Configuration : 表示该类使用Spring基于Java配置
@ComponentScan : 启用组件扫描
@EnableAutoConfiguration : Spring Boot 魔力来源，启用自动配置

创建一个 Controller

src/main/java/com/example/springboot/hello/controller/HellController.java

package com.example.springboot.hello.controller;

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

@RestController
public class HelloController {

	@RequestMapping(value = "/index", method = RequestMethod.GET)
	public String index() {
		return "Greetings from Spring Boot!";
	}

}

@RestController 注解表示该Controller是RESTful风格接口
@RequestMapping 注解定义请求URL和请求方法

运行 SpringBoot Application

有很多种方式可以运行 SpringBoot Application。
开发过程中可以直接执行 Application main 方法，或者通过maven install 方式启动
打包可以通过maven package 打包
打包后运行可以通过java -jar XXX.jar 方式运行可执行 jar 包
一般控制台可以看到如下输出：

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v1.5.9.RELEASE)

2017-11-29 14:46:28.397  INFO 9916 --- [           main] c.e.s.hello.SpringBootHelloApplication   : Starting SpringBootHelloApplication on DESKTOP-1MESJ85 with PID 9916 (started by Richard in D:\lxmuse-spring-boot\building an application with spring boot\spring-boot-hello)
2017-11-29 14:46:28.400  INFO 9916 --- [           main] c.e.s.hello.SpringBootHelloApplication   : No active profile set, falling back to default profiles: default
2017-11-29 14:46:28.492  INFO 9916 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@5e955596: startup date [Wed Nov 29 14:46:28 CST 2017]; root of context hierarchy
2017-11-29 14:46:29.600  INFO 9916 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http)
2017-11-29 14:46:29.608  INFO 9916 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2017-11-29 14:46:29.609  INFO 9916 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.23
2017-11-29 14:46:29.672  INFO 9916 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2017-11-29 14:46:29.673  INFO 9916 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 1187 ms
2017-11-29 14:46:29.761  INFO 9916 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Mapping servlet: 'dispatcherServlet' to [/]
2017-11-29 14:46:29.764  INFO 9916 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
2017-11-29 14:46:29.764  INFO 9916 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2017-11-29 14:46:29.765  INFO 9916 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2017-11-29 14:46:29.765  INFO 9916 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]
2017-11-29 14:46:29.999  INFO 9916 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@5e955596: startup date [Wed Nov 29 14:46:28 CST 2017]; root of context hierarchy
2017-11-29 14:46:30.037  INFO 9916 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/index],methods=[GET]}" onto public java.lang.String com.example.springboot.hello.controller.HelloController.index()
2017-11-29 14:46:30.040  INFO 9916 --- [           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)
2017-11-29 14:46:30.041  INFO 9916 --- [           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,javax.servlet.http.HttpServletResponse)
2017-11-29 14:46:30.062  INFO 9916 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-11-29 14:46:30.062  INFO 9916 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-11-29 14:46:30.085  INFO 9916 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-11-29 14:46:30.168  INFO 9916 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2017-11-29 14:46:30.206  INFO 9916 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8080 (http)
2017-11-29 14:46:30.212  INFO 9916 --- [           main] c.e.s.hello.SpringBootHelloApplication   : Started SpringBootHelloApplication in 2.122 seconds (JVM running for 3.326)

访问 SpringBoot Application

同理有很多种方式可以访问 SpringBoot Application。
如果是 GET 请求，可以直接通过浏览器访问
如果是其他请求，可以使用浏览器REST client 模拟请求，或者使用 PostMan 等软件模拟请求

使用 PostMan 发起 GET 请求，地址是：localhost:8080/index
SpringBoot 工程默认的地址是localhost:8080
可以看到返回结果是 Greetings from Spring Boot!

添加单元测试

package com.example.springboot.hello;

import static org.hamcrest.Matchers.equalTo;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;


import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.http.MediaType;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.request.MockMvcRequestBuilders;

@RunWith(SpringRunner.class)
@SpringBootTest
@AutoConfigureMockMvc
public class SpringBootHelloApplicationTests {

	@Autowired
	private MockMvc mockMvc;

	@Test
	public void testIndex() throws Exception {
		mockMvc.perform(MockMvcRequestBuilders.get("/index").accept(MediaType.APPLICATION_JSON))
			.andExpect(status().isOk())
			.andExpect(content().string(equalTo("Greetings from Spring Boot!")));
	}
}

也可以对 HelloController 做单独的单元测试：

package com.example.springboot.hello.controller;

import static org.hamcrest.Matchers.equalTo;
import static org.junit.Assert.assertThat;

import java.net.URL;

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.context.embedded.LocalServerPort;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.web.client.TestRestTemplate;
import org.springframework.http.ResponseEntity;
import org.springframework.test.context.junit4.SpringRunner;

@RunWith(SpringRunner.class)
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
public class HelloControllerTest {

	@LocalServerPort
	private int port;

	private URL base;

	@Autowired
	private TestRestTemplate template;

	@Before
	public void setUp() throws Exception {
		this.base = new URL("http://localhost:" + port + "/index");
	}

	@Test
	public void testIndex() throws Exception {
		ResponseEntity<String> response = template.getForEntity(base.toString(),
			String.class);
		assertThat(response.getBody(), equalTo("Greetings from Spring Boot!"));
	}
}

具体代码已上传GitHub-lxmuse