Spring Boot 的第一个Demo：

打开Idea-> new Project ->Spring Initializr ->填写group、artifact ->钩上web(开启web功能）->点下一步就行了。

目录结构如下：

• pom文件为基本的依赖管理文件
• resouces 资源文件 
  
  • statics 静态资源
  • templates 模板资源
  • application.yml 配置文件
• SpringbootApplication程序的入口。

来看配置文件：

依赖文件：

<?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>

    <groupId>com</groupId>
    <artifactId>springboot01</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>springboot01</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.4.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>


</project>

其中spring-boot-starter-web不仅包含spring-boot-starter,还自动开启了web功能。

来看第一demo:

建个controller

@RestController
public class HelloController {

   @RequestMapping("/")
   public String index(){
      return "Greetings from spring Boot1";
   }
}

启动SpringbootFirstApplication的main方法，打开浏览器localhost:8080,浏览器显示：

我们来看一下，默认下导入的依赖包有：

@SpringBootApplication
public class Springboot01Application {

   public static void main(String[] args) {
      SpringApplication.run(Springboot01Application.class, args);
   }

   @Bean
   public CommandLineRunner commandLineRunner(ApplicationContext ctx){
      return args -> {
         System.out.println("Let's inspect the beans provided by Spring Boot:");

         String[] baenNames =ctx.getBeanDefinitionNames();
         Arrays.sort(baenNames);
         for (String beanName:baenNames){
            System.out.println(beanName);
         }
      };
   }
}

导入的包，结果如下：

接着看测试的方式：

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

   @Autowired
   private MockMvc mvc;

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

接着来看加过，看与之前的输出有什么区别：

MockHttpServletResponse:

           Status = 200

    Error message = null

          Headers = {Content-Type=[application/json;charset=UTF-8], Content-Length=[27]}

     Content type = application/json;charset=UTF-8

             Body = Greetings from spring Boot1

    Forwarded URL = null

   Redirected URL = null

          Cookies = []

java.lang.ClassCastException: org.springframework.test.web.client.match.ContentRequestMatchers$$Lambda$351/700837405 cannot be cast to org.springframework.test.web.servlet.ResultMatcher

at com.springboot01.HelloControllerTest.getHello(HelloControllerTest.java:29)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.lang.reflect.Method.invoke(Method.java:498)

at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)

at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)

at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)

at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)

at org.springframework.test.context.junit4.statements.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:73)

at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:83)

at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)

at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)

at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)

at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)

at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:251)

at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)

at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)

at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)

at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)

at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)

at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)

at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)

at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)

at org.junit.runners.ParentRunner.run(ParentRunner.java:363)

at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)

at org.junit.runner.JUnitCore.run(JUnitCore.java:137)

at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)

at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)

at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)

at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

2018-09-11 09:34:29.112  INFO 13580 --- [       Thread-3] o.s.w.c.s.GenericWebApplicationContext   : Closing org.springframework.web.context.support.GenericWebApplicationContext@1ed6388a: startup date [Tue Sep 11 09:34:27 CST 2018]; root of context hierarchy

总结：
1.学到的东西：

    1.1.学习了Springboot的一些基础知识。

2.明天计划的事情：

    2.1.继续准备复盘申请。

    2.2.继续学习Spring boot和Spring cloud 。

3.遇到的问题：

4.收获：

       收获了上述知识点，坚持！