springboot of Silicon Valley still lecture summary

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1. Brief introduction
   

2. grammar
   

3. Configure get
   
   application.yml

   person:
     name: 小柯
     age: 16
     date: 2020/01/05
     boss: true
     maps: {k1: v1, k2: w5}
     list:
       - aa
       - bb
       - cc
       - dd
     dog:
       name: xiaogou
       age: 15

   application.properties

   person.name=小王
   person.age=100
   person.boss=false
   person.date=2020/06/05
   person.list=1,5,6,8
   person.maps.aa=123
   person.maps.bb=456
   person.dog=456

   Acquisition (method)

   @ConfigurationProperties(prefix = "person")
   @Component
   public class Person {
       private String name;
       private Integer age;
       private Date date;
       private Boolean boss;
       private Map<String, Object> maps;
       private List<Object> list;
       private Dog dog;
       //getset

   Get (Method II)

   @Component
   public class Person {
       @Value("${person.name}")
       private String name;
       @Value("${person.age}")
       private Integer age;
       @Value("${person.date}")
       private Date date;
       @Value("${person.boss}")

    

4. @ConfigurationProperties and @Value difference
   

 

@PropertySource和@ImportResource

• @PropertySource load the specified file location

  @PropertySource(value = {"classpath:person.properties"})
  @ConfigurationProperties(prefix = "person")
  @Component
  public class Person {
      private String name;
      private Integer age;
      private Date date;
      private Boolean boss;
      private Map<String, Object> maps;
      private List<Object> list;
      private Dog dog;
      //GetSet

   

• @ImportResource import Spring configuration file, so that the configuration file to take effect
  
  1, create bean.xml
  2, create Service
  3, test

  package springboot.io;
  import org.junit.jupiter.api.Test;
  import org.junit.runner.RunWith;
  import org.springframework.beans.factory.annotation.Autowired;
  import org.springframework.boot.test.context.SpringBootTest;
  import org.springframework.context.ApplicationContext;
  import org.springframework.test.context.junit4.SpringRunner;
  @RunWith(SpringRunner.class)
  @SpringBootTest
  public  class SpringbootStartApplicationTests {
      @Autowired
      ApplicationContext applicationContext;
      @Test
      public void testHelloService(){
          boolean helloService = applicationContext.containsBean("helloService");
          System.out.println(helloService);
      }
  
  }
  

  4, false results
  plus 5, the boot class: @ImportResource (locations = { "CLASSPATH: bean.xml"})
  . 6, in place of the test is successful configuration class
  7, springboot not recommended @ImportResource introduced using a full injection configuration
  8, delete bean.xml, delete @ImportResource notes on startup class
  9, (a way) to create a configuration class HelloConfig
          use @Configuration and @Bean

  package springboot.io.config;
  import org.springframework.context.annotation.Bean;
  import org.springframework.context.annotation.Configuration;
  import springboot.io.service.HelloService;
  import springboot.io.service.impl.HelloServiceImpl;
  @Configuration
  public class HelloConfig {
      @Bean
      public HelloService helloService(){
          return new HelloServiceImpl();
      }
  }
  

          (Mode 1) using @Service

 

Profile of placeholders

• Symbols: $ {}
• Can write the random number {random.uuid}
• Value can be obtained previously configured, if there is no default can be set
  $ {person.age: 20}

 

Many environmental profile

1. Default application.properties
2. Use other environmental spring.profiles.active = dev
3. Project start: - spring.profile.active = dev added to the Program arguments in
4. 命令行：java -jar xxx.jar --spring.profile.active=dev 
5. 虚拟机参数 -Dspring profiles.avtive=dev  加入到VM options

 

配置文件之加载位置

1. 可以加载的位置(优先级由高到低，到优先级会覆盖低优先级配置，前面配置文件没有的，后面的会补上)
   file:./config   file:./  classpath:./config  classpath:./
2. spring.config.location来改变默认的配置文件位置
   使用条件：项目打包好之后，启动项目改变默认配置文件位置，且与默认配置文件互补。
   使用方式：java -jar xxx.jar  --spring.config.location=D:/xiaoke.properties

自动配置原理

1. 启动主配置@SpringBootApplication
2. 开启注解：@EnableAutoConfiguration
3. 导入@Import(EnableAutoConfigurationImportSelector.class)
   父类：AutoConfigurationImportSelector
   List<String> configurations = getCandidateConfigurations(annotationMetadata,attributes);

   List<String> configurations = SpringFactoriesLoader.loadFactoryNames(
         getSpringFactoriesLoaderFactoryClass(), getBeanClassLoader());
   SpringFactoriesLoader.loadFactoryNames()扫描所有jar包类路径下META-INF/spring.factories,
   把扫描的这些文件内容包装成properties对象，封装到result中返回

4. 获取META-INF/spring.factories

       public static List<String> loadFactoryNames(Class<?> factoryClass, ClassLoader classLoader) {
           String factoryClassName = factoryClass.getName();
   
           try {
               Enumeration<URL> urls = classLoader != null ? classLoader.getResources("META-INF/spring.factories") : ClassLoader.getSystemResources("META-INF/spring.factories");
               ArrayList result = new ArrayList();
   
               while(urls.hasMoreElements()) {
                   URL url = (URL)urls.nextElement();
                   Properties properties = PropertiesLoaderUtils.loadProperties(new UrlResource(url));
                   String factoryClassNames = properties.getProperty(factoryClassName);
                   result.addAll(Arrays.asList(StringUtils.commaDelimitedListToStringArray(factoryClassNames)));
               }
   
               return result;
           } catch (IOException var8) {
               throw new IllegalArgumentException("Unable to load [" + factoryClass.getName() + "] factories from location [" + "META-INF/spring.factories" + "]", var8);
           }
       }

    

5. 以HttpEncodingAutoConfiguration为例
    

   //表示这是一个配置类，以前编写的配置文件一样，也可以给容器中添加组件
   @Configuration
   //启动指定类，@EnableConfigurationProperties功能：将配置文件中对应的值和HttpEncodingProperties绑定起来
   @EnableConfigurationProperties(HttpEncodingProperties.class)
   //判断当前应用是否是web应用，如果是，当前配置类生效
   @ConditionalOnWebApplication
   //判断当前项目有没有这个类，CharacterEncodingFilter：springMvc中进行乱码解决的过滤器
   @ConditionalOnClass(CharacterEncodingFilter.class)
   
   //判断配置文件中是否存在某个配置，spring.http.encoding.enabled;如果不存在判断是成立的
   //即使我们配置文件中不配置spring.http.encoding.enabled = true 也是默认生效的
   @ConditionalOnProperty(prefix = "spring.http.encoding", value = "enabled", matchIfMissing = true)
   public class HttpEncodingAutoConfiguration {

    

6. debug = true 在控制台打印出那些自动配置类生效；

7. 怎么解析视图的，后面慢慢理解