Please set spring.main.web-application-type=reactive or remove spring-boot-starter-web dependency.

Posted 2023-03-23 java-zh

一、问题

在启动springcloud的gateway模块的时候报错Please set spring.main.web-application-type=reactive or remove spring-boot-starter-web dependency.

二、问题产生的原因

gateway组件中的 spring-boot-starter-webflux 和 springboot作为web项目启动必不可少的 spring-boot-starter-web 出现冲突。

三、解决方案(任选一种就可以)

3.1 注释pom.xml内容

在gateway的pom文件上注释掉spring-boot-starter-web代码

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

3.2修改配置文件

在配置文件上加上

spring:
    main:
        web-application-type: reactive

解释：这里面涉及到springboot的启动流程因为spring-boot-starter-webflux包，在springboot启动类型里面表示的就是reactive。我们可以看源码，了解一下springboot启动流程

一步一步点进去

这是springApplication构造方法，我们先看构造方法

点进去

3.2.1通过springboot源码解释

springApplication构造源码(不同版本会有差异，当前版本是2.6.1)

public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) 
        
        this.sources = new LinkedHashSet();
        // 在控制台打印banner.txt文本内容
        this.bannerMode = Mode.CONSOLE;
        this.logStartupInfo = true;
        this.addCommandLineProperties = true;
        this.addConversionService = true;
        this.headless = true;
        this.registerShutdownHook = true;
        this.additionalProfiles = Collections.emptySet();
        this.isCustomEnvironment = false;
        this.lazyInitialization = false;
        this.applicationContextFactory = ApplicationContextFactory.DEFAULT;
        this.applicationStartup = ApplicationStartup.DEFAULT;
        // 开始输resourceLoader注入了属性null
        this.resourceLoader = resourceLoader;
        Assert.notNull(primarySources, "PrimarySources must not be null");
        //将启动类从数组重新封装Set,注入到primarySources当中
        this.primarySources = new LinkedHashSet(Arrays.asList(primarySources));
        /**
          *webApplicationType有三种类型,REACTIVE,SERVLET,NONE
          *  引入spring-boot-starter-web就是SERVLET
          *  引入spring-boot-starter-webflux就是REACTIVE
          *  没有就是NONE
          */
        this.webApplicationType = WebApplicationType.deduceFromClasspath();
        /**
          *从spring-cloud-context的jar包的META-INF/spring.factories文件中得到key为org.springfra           *mework.boot.BootstrapRegistryInitializer的全类名集合,进行实例化,然后注入 bootstrapRegi
          *stryInitializers 属性，其中核心方法getSpringFactoriesInstances
          *下面有getSpringFactoriesInstances方法源码详解
          *这里简单的解释一下getSpringFactoriesInstances方法就是从META-INF/spring.factories读取配
          *置文件            
          */
        this.bootstrapRegistryInitializers = new ArrayList(this.getSpringFactoriesInstances(BootstrapRegistryInitializer.class));
        /**
          *依然调用getSpringFactoriesInstances方法
          *从spring-boot的jar包的META-INF/spring.factories文件中得到key为org.springframework.            *context.ApplicationContextInitializer的全类名集合，然后进行实例化，然后注入initializers
          *(初始化容器集合)属性  
          */
        this.setInitializers(this.getSpringFactoriesInstances(ApplicationContextInitializer.class));
        //跟上面一样,这里是得到监听器的集合,并注入
        this.setListeners(this.getSpringFactoriesInstances(ApplicationListener.class));
        //获取当前的main方法运行的类，也就是我们的主类
        this.mainApplicationClass = this.deduceMainApplicationClass();
    

上面说的META-INF/spring.factories都是在springboot.jar包中，不过BootstrapRegistryInitializer是在spring-cloud-context中。

3.2.2了解getSpringFactoriesInstances方法

随便选一个点进去

  private <T> Collection<T> getSpringFactoriesInstances(Class<T> type, Class<?>[] parameterTypes, Object... args) 
        ClassLoader classLoader = this.getClassLoader();
        /** SpringFactoriesLoader.loadFactoryNames(type, classLoader)这里才是核心，
          *这个方法会扫描所有jar包类路径下 META-INF/spring.factories
          */
        Set<String> names = new LinkedHashSet(SpringFactoriesLoader.loadFactoryNames(type, classLoader));
        List<T> instances = this.createSpringFactoriesInstances(type, parameterTypes, classLoader, args, names);
        AnnotationAwareOrderComparator.sort(instances);
        return instances;
    

Please check that your locale settings问题

问题描述：

perl: warning: Setting locale failed.

perl: warning: Please check that your locale settings:

LANGUAGE = "en_US:en",

LC_ALL = (unset),

LC_CTYPE = "zh_CN.UTF-8",

LANG = "en_US.UTF-8"

are supported and installed on your system.

perl: warning: Falling back to a fallback locale ("en_US.UTF-8").

perl: warning: Setting locale failed.

perl: warning: Please check that your locale settings:

LANGUAGE = "en_US:en",

LC_ALL = (unset),

LC_CTYPE = "zh_CN.UTF-8",

LANG = "en_US.UTF-8"

are supported and installed on your system.

perl: warning: Falling back to a fallback locale ("en_US.UTF-8").

解决方案：

vi /root/.bashrc

再最底部加上

export LC_ALL=C

或者直接运行

echo "export LC_ALL=C" >> /root/.bashrc

然后执行一下：

source /root/.bashrc

作者：vcancy
链接：https://www.jianshu.com/p/32544edd7362
来源：简书
简书著作权归作者所有，任何形式的转载都请联系作者获得授权并注明出处。