问题：报错误
Caused by: java.lang.ClassNotFoundException: com.fasterxml.jackson.core.Version
注意：分析错误堆栈是从最下面往最上面分析，解决问题时也是从下往上修复。比如下面完整的错误
堆栈信息，我们就从最下面的 Caused by: java.lang.ClassNotFoundException: com.fasterxml.jackson.core.Version 开始处理，在这里只要解决了 jackson 的依赖问题就解决了。
Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled.
2018-06-24 23:05:17.641 ERROR 9816 --- [ main] o.s.boot.SpringApplication : Application startup failed
org.springframework.context.ApplicationContextException: Failed to start bean 'org.springframework.cloud.netflix.eureka.EurekaDiscoveryClientConfiguration'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'scopedTarget.eurekaClient' defined in class path resource [org/springframework/cloud/netflix/eureka/EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.netflix.discovery.EurekaClient]: Factory method 'eurekaClient' threw exception; nested exception is java.lang.RuntimeException: Failed to initialize DiscoveryClient!
at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:176) ~[spring-context-4.3.17.RELEASE.jar:4.3.17.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor.access$200(DefaultLifecycleProcessor.java:50) ~[spring-context-4.3.17.RELEASE.jar:4.3.17.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:346) ~[spring-context-4.3.17.RELEASE.jar:4.3.17.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:149) ~[spring-context-4.3.17.RELEASE.jar:4.3.17.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:112) ~[spring-context-4.3.17.RELEASE.jar:4.3.17.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:880) ~[spring-context-4.3.17.RELEASE.jar:4.3.17.RELEASE]
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.finishRefresh(EmbeddedWebApplicationContext.java:144) ~[spring-boot-1.5.13.RELEASE.jar:1.5.13.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:546) ~[spring-context-4.3.17.RELEASE.jar:4.3.17.RELEASE]
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) ~[spring-boot-1.5.13.RELEASE.jar:1.5.13.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:693) [spring-boot-1.5.13.RELEASE.jar:1.5.13.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:360) [spring-boot-1.5.13.RELEASE.jar:1.5.13.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:303) [spring-boot-1.5.13.RELEASE.jar:1.5.13.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118) [spring-boot-1.5.13.RELEASE.jar:1.5.13.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107) [spring-boot-1.5.13.RELEASE.jar:1.5.13.RELEASE]
at com.example.server1.HellApplication.main(HellApplication.java:11) [classes/:na]
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'scopedTarget.eurekaClient' defined in class path resource [org/springframework/cloud/netflix/eureka/EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.netflix.discovery.EurekaClient]: Factory method 'eurekaClient' threw exception; nested exception is java.lang.RuntimeException: Failed to initialize DiscoveryClient!
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:599) ~[spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1181) ~[spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1075) ~[spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:513) ~[spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE]
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory$2.getObject(AbstractBeanFactory.java:351) ~[spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE]
at org.springframework.cloud.context.scope.GenericScope$BeanLifecycleWrapper.getBean(GenericScope.java:359) ~[spring-cloud-context-1.1.1.RELEASE.jar:1.1.1.RELEASE]
at org.springframework.cloud.context.scope.GenericScope.get(GenericScope.java:176) ~[spring-cloud-context-1.1.1.RELEASE.jar:1.1.1.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:346) ~[spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE]
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE]
at org.springframework.aop.target.SimpleBeanTargetSource.getTarget(SimpleBeanTargetSource.java:35) ~[spring-aop-4.3.17.RELEASE.jar:4.3.17.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:192) ~[spring-aop-4.3.17.RELEASE.jar:4.3.17.RELEASE]
at com.sun.proxy.$Proxy67.getApplications(Unknown Source) ~[na:na]
at org.springframework.cloud.netflix.eureka.EurekaDiscoveryClientConfiguration.maybeInitializeClient(EurekaDiscoveryClientConfiguration.java:120) ~[spring-cloud-netflix-eureka-client-1.1.5.RELEASE.jar:1.1.5.RELEASE]
at org.springframework.cloud.netflix.eureka.EurekaDiscoveryClientConfiguration.start(EurekaDiscoveryClientConfiguration.java:97) ~[spring-cloud-netflix-eureka-client-1.1.5.RELEASE.jar:1.1.5.RELEASE]
at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:173) ~[spring-context-4.3.17.RELEASE.jar:4.3.17.RELEASE]
... 14 common frames omitted
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.netflix.discovery.EurekaClient]: Factory method 'eurekaClient' threw exception; nested exception is java.lang.RuntimeException: Failed to initialize DiscoveryClient!
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:189) ~[spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE]
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:588) ~[spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE]
... 29 common frames omitted
Caused by: java.lang.RuntimeException: Failed to initialize DiscoveryClient!
at com.netflix.discovery.DiscoveryClient.<init>(DiscoveryClient.java:441) ~[eureka-client-1.4.10.jar:1.4.10]
at com.netflix.discovery.DiscoveryClient.<init>(DiscoveryClient.java:304) ~[eureka-client-1.4.10.jar:1.4.10]
at org.springframework.cloud.netflix.eureka.CloudEurekaClient.<init>(CloudEurekaClient.java:51) ~[spring-cloud-netflix-eureka-client-1.1.5.RELEASE.jar:1.1.5.RELEASE]
at org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration.eurekaClient(EurekaClientAutoConfiguration.java:180) ~[spring-cloud-netflix-eureka-client-1.1.5.RELEASE.jar:1.1.5.RELEASE]
at org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration$$EnhancerBySpringCGLIB$$445034b.CGLIB$eurekaClient$1(<generated>) ~[spring-cloud-netflix-eureka-client-1.1.5.RELEASE.jar:1.1.5.RELEASE]
at org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration$$EnhancerBySpringCGLIB$$445034b$$FastClassBySpringCGLIB$$718ed4a4.invoke(<generated>) ~[spring-cloud-netflix-eureka-client-1.1.5.RELEASE.jar:1.1.5.RELEASE]
at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:228) ~[spring-core-4.3.17.RELEASE.jar:4.3.17.RELEASE]
at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:358) ~[spring-context-4.3.17.RELEASE.jar:4.3.17.RELEASE]
at org.springframework.cloud.netflix.eureka.EurekaClientAutoConfiguration$RefreshableEurekaClientConfiguration$$EnhancerBySpringCGLIB$$445034b.eurekaClient(<generated>) ~[spring-cloud-netflix-eureka-client-1.1.5.RELEASE.jar:1.1.5.RELEASE]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_152]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_152]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_152]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_152]
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:162) ~[spring-beans-4.3.17.RELEASE.jar:4.3.17.RELEASE]
... 30 common frames omitted
Caused by: java.lang.NoClassDefFoundError: com/fasterxml/jackson/core/Version
at com.netflix.discovery.converters.EurekaJacksonCodec.<clinit>(EurekaJacksonCodec.java:55) ~[eureka-client-1.4.10.jar:1.4.10]
at com.netflix.discovery.converters.wrappers.CodecWrappers$LegacyJacksonJson.<init>(CodecWrappers.java:285) ~[eureka-client-1.4.10.jar:1.4.10]
at com.netflix.discovery.converters.wrappers.CodecWrappers.create(CodecWrappers.java:125) ~[eureka-client-1.4.10.jar:1.4.10]
at com.netflix.discovery.converters.wrappers.CodecWrappers.getEncoder(CodecWrappers.java:75) ~[eureka-client-1.4.10.jar:1.4.10]
at com.netflix.discovery.converters.wrappers.CodecWrappers.getEncoder(CodecWrappers.java:66) ~[eureka-client-1.4.10.jar:1.4.10]
at com.netflix.discovery.provider.DiscoveryJerseyProvider.<init>(DiscoveryJerseyProvider.java:68) ~[eureka-client-1.4.10.jar:1.4.10]
at com.netflix.discovery.shared.transport.jersey.EurekaJerseyClientImpl$EurekaJerseyClientBuilder$MyDefaultApacheHttpClient4Config.<init>(EurekaJerseyClientImpl.java:190) ~[eureka-client-1.4.10.jar:1.4.10]
at com.netflix.discovery.shared.transport.jersey.EurekaJerseyClientImpl$EurekaJerseyClientBuilder.build(EurekaJerseyClientImpl.java:166) ~[eureka-client-1.4.10.jar:1.4.10]
at com.netflix.discovery.shared.transport.jersey.JerseyEurekaHttpClientFactory$JerseyEurekaHttpClientFactoryBuilder.buildLegacy(JerseyEurekaHttpClientFactory.java:205) ~[eureka-client-1.4.10.jar:1.4.10]
at com.netflix.discovery.shared.transport.jersey.JerseyEurekaHttpClientFactory$JerseyEurekaHttpClientFactoryBuilder.build(JerseyEurekaHttpClientFactory.java:186) ~[eureka-client-1.4.10.jar:1.4.10]
at com.netflix.discovery.shared.transport.jersey.JerseyEurekaHttpClientFactory.create(JerseyEurekaHttpClientFactory.java:143) ~[eureka-client-1.4.10.jar:1.4.10]
at com.netflix.discovery.shared.transport.jersey.TransportClientFactories.newTransportClientFactory(TransportClientFactories.java:49) ~[eureka-client-1.4.10.jar:1.4.10]
at com.netflix.discovery.DiscoveryClient.scheduleServerEndpointTask(DiscoveryClient.java:477) ~[eureka-client-1.4.10.jar:1.4.10]
at com.netflix.discovery.DiscoveryClient.<init>(DiscoveryClient.java:428) ~[eureka-client-1.4.10.jar:1.4.10]
... 43 common frames omitted
Caused by: java.lang.ClassNotFoundException: com.fasterxml.jackson.core.Version
at java.net.URLClassLoader.findClass(URLClassLoader.java:381) ~[na:1.8.0_152]
at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[na:1.8.0_152]
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:338) ~[na:1.8.0_152]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[na:1.8.0_152]
... 57 common frames omitted
Caused by: java.lang.NoClassDefFoundError: com/fasterxml/jackson/core/Version
Caused by: java.lang.ClassNotFoundException: com.fasterxml.jackson.core.Version
这个两个异常信息是同一个异常的两种不同表示方式。
处理：在 POM.XML 配置文件中，配置 jackson 依赖（红色部分）。
<?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.example</groupId>
<artifactId>server1</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>server1</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.13.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<!--
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.3.RELEASE</version>
<relativePath/>
</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</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-eureka</artifactId>
<version>1.4.4.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
<version>1.4.4.RELEASE</version>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<!-- <version>${log4j.version}</version> -->
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-annotations</artifactId>
<version>2.9.6</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>2.9.6</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.9.6</version>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>Brixton.SR5</version>
<type>pom</type>
<scope>import</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>