Spring Cloud 启动错误 - java.lang.No

启动报错

16:41:12.632 [main] ERROR org.springframework.boot.SpringApplication - Application run failed
java.lang.NoSuchMethodError: org.springframework.boot.builder.SpringApplicationBuilder.<init>([Ljava/lang/Object;)V
    at org.springframework.cloud.bootstrap.BootstrapApplicationListener.bootstrapServiceContext(BootstrapApplicationListener.java:157)
    at org.springframework.cloud.bootstrap.BootstrapApplicationListener.onApplicationEvent(BootstrapApplicationListener.java:98)
    at org.springframework.cloud.bootstrap.BootstrapApplicationListener.onApplicationEvent(BootstrapApplicationListener.java:64)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139)
    at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:127)
    at org.springframework.boot.context.event.EventPublishingRunListener.environmentPrepared(EventPublishingRunListener.java:76)
    at org.springframework.boot.SpringApplicationRunListeners.environmentPrepared(SpringApplicationRunListeners.java:53)
    at org.springframework.boot.SpringApplication.prepareEnvironment(SpringApplication.java:342)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:305)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1204)
    at com.example.eureka.EurekaServerApplication.main(EurekaServerApplication.java:12)
Disconnected from the target VM, address: '127.0.0.1:56615', transport: 'socket'

是由于spring boot版本兼容性导致的，在pom.xml中修改配置文件，修改前：

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.9.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
</parent>

而eureka的配置

 <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>Dalston.SR3</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

尤其是第一行信息，似乎提示一个莫名其妙的无此方法错误。Spring boot框架很多组件都是基于依赖注入（DI），有些错误在编译时可能无法被检测出来，只有在运行时才暴露出来。既然提示无此方法，那么肯定是某个组件（包）有问题：要么未被注入；要么版本版本不对。

打开了spring cloud官网，发现SR3版本依赖于spring boot 1.5.x。如此看来是这两个组件的版本发生了冲突，所以解决方法也比较简单：要么降级spring boot版本，要么升级spring cloud版本。