springboot总结

初始化项目

https://start.spring.io/

配置启动

获取 context

public static void main(String[] args) {
	ApplicationContext context = SpringApplication.run(SpringDemoApplication.class, args);
}

三种启动写法，并做一些启动设置

1. SpringApplication.run
2. new SpringApplication()

	public static void main(String[] args) {
//		ApplicationContext context = SpringApplication.run(SpringDemoApplication.class, args);
		SpringApplication app = new SpringApplication(SpringDemoApplication.class);
		app.setBannerMode(Banner.Mode.OFF);
		ApplicationContext context = app.run(args);
	}

3. new SpringApplicationBuilder()

public static void main(String[] args) {
	ApplicationContext run = new SpringApplicationBuilder()
		.sources(SpringDemoApplication.class)
		.bannerMode(Banner.Mode.CONSOLE)
		.run(args);
}

替换 Logo

resources/banner.txt

配置文件中指定启动的类

spring.main.sources=com.koory1st.spring_demo.SpringDemoApplication

启动后回调

• CommandLineRunner

@SpringBootApplication
public class SpringDemoApplication implements CommandLineRunner {
	@Override
	public void run(String... args) throws Exception {
	}
}

• ApplicationRunner

@SpringBootApplication
public class SpringDemoApplication implements ApplicationRunner {
 @Override
 public void run(ApplicationArguments args) throws Exception {
 }
}

配置启动类型

可配置的值：none, web,

spring.main.web-application-type=servlet

web 工程启动顺序

1. 启动 ioc 容器
2. 启动内嵌的 tomcat

自动化配置

Springboot 的自动化配置是在org.springframework.boot.autoconfigure实现的。大部分的预先配置都是在META-INF/spring.factories这里配置的。

禁止自动化配置

• 在代码中

@SpringBootApplication(exclude={DataSourceAutoConfiguration.class})

• 配置文件中

spring.autoconfigure.exclude=

bean

添加 bean

1. @Component()
2. @Configuration(其实也是@Component)
3. @Configuration + @Bean
4. @Import(MyBean.class)
5. @Configuration + @ComponentScan
6. @ImportResource(locations = “classpath:applicationContext.xml”)

延迟初始化 Bean

全局延迟初始化

• 使用配置文件

spring.main.lazy-initialization=true

• 在代码中

public static void main(String[] args) {
	ApplicationContext run = new SpringApplicationBuilder()
		.lazyInitialization(true)
		.sources(SpringDemoApplication.class)
		.bannerMode(Banner.Mode.CONSOLE)
		.run(args);
}

在全局都是延迟化的情况下，使用@Lazy(false)注解使某个 Bean 不延迟初始化。

敏感信息加密

一个三方类库 jasypt

gradle

implementation group: 'com.github.ulisesbocchio', name: 'jasypt-spring-boot-starter', version: '3.0.3'

maven

<dependency>
    <groupId>com.github.ulisesbocchio</groupId>
    <artifactId>jasypt-spring-boot-starter</artifactId>
    <version>3.0.3</version>
</dependency>

配置文件需要配置一个密码

jasypt.encryptor.password=1234

@Autowired
private StringEncryptor stringEncryptor;

@Test
public void encryptString() {
	String abc = stringEncryptor.encrypt("abc");
	System.out.println("abc = " + abc);

	String decrypt = stringEncryptor.decrypt(abc);
	System.out.println("decrypt = " + decrypt);
}

之后，就可以使用以下的方式配置了，jasypt 会解密

name=ENV(VAHGUMgVllLkHelXYfCa2zFsMs/OziuhGAovjSh7PTx+KBSESpcAs49a73w640LQ)

跨域 CORS

@Configuration
public class MyConfig {
  public WebMvcConfigurer corsConfigurer() {
    return new WebMvcConfigurer() {
      @Override
      public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/web/**");
      }
    };
  }
}

@Configuration
public class MyConfig implements WebMvcConfigurer {
  @Override
  public void addCorsMappings(CorsRegistry registry) {
    registry.addMapping("/web/**");
  }
}

静态资源

默认位置

• /static
• /public
• /resoures
• /META-INF/resources

指定

spring.resources.static-locations=classpath:/my-static

读取配置文件

@Value

@ConfigurationProperties(prefix = “my”)

Environment

  @Autowired
  private Environment env;


env.getProperty("my.abc");

有嵌套结构，使用静态内部类读取

参考

org.springframework.boot.autoconfigure.web.ServerProperties

线程池异步调用 @Async

配置上添加 @EnableAsync

@EnableAsync
@Configuration

方法上添加 @Async

@Async
public void sendMsg() {
  log.info("sendMsg" + Thread.currentThread().getName());
}

注意

不能自类调用Async方法

不能自类调用Async方法，因为要用Spring代理后的bean，若必须要在自己类里使用，需要获取bean后再做调用。

返回值只能是 void 或者 Future<>

自定义线程池

参考How To Do @Async in Spring

@Configuration
@EnableAsync
public class SpringAsyncConfig {
    
    @Bean(name = "threadPoolTaskExecutor")
    public Executor threadPoolTaskExecutor() {
        return new ThreadPoolTaskExecutor();
    }
}

@Async("threadPoolTaskExecutor")
public void asyncMethodWithConfiguredExecutor() {
    System.out.println("Execute method with configured executor - "
      + Thread.currentThread().getName());
}

全局覆盖线程池

参考How To Do @Async in Spring

@Configuration
@EnableAsync
public class SpringAsyncConfig implements AsyncConfigurer {
    
    @Override
    public Executor getAsyncExecutor() {
        return new ThreadPoolTaskExecutor();
    }
}

异常处理

参考How To Do @Async in Spring

public class CustomAsyncExceptionHandler
  implements AsyncUncaughtExceptionHandler {

    @Override
    public void handleUncaughtException(
      Throwable throwable, Method method, Object... obj) {
 
        System.out.println("Exception message - " + throwable.getMessage());
        System.out.println("Method name - " + method.getName());
        for (Object param : obj) {
            System.out.println("Parameter value - " + param);
        }
    }
}

或者

@Configuration
@EnableAsync
public class SpringAsyncConfig implements AsyncConfigurer {
    
    @Override
    public Executor getAsyncExecutor() {
        return new ThreadPoolTaskExecutor();
    }
  
    @Override
    public AsyncUncaughtExceptionHandler getAsyncUncaughtExceptionHandler() {
        return new CustomAsyncExceptionHandler();
    }
}

Websocket

implementation 'org.springframework.boot:spring-boot-starter-websocket'

​