如何解决使用 Spring Boot 2.4.1
我正在使用 Spring Boot 2.4.1 和 Eureka 开发应用程序。我成功启动了 Eureka 服务器，但是使用 Eureka 客户端时出现以下错误：
Caused by: java.lang.classNotFoundException: com.sun.jersey.client.apache4.ApacheHttpClient4
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:606) ~[na:na]
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:168) ~[na:na]
at java.base/java.lang.classLoader.loadClass(ClassLoader.java:522) ~[na:na]
... 55 common frames omitted
...
Caused by: java.lang.NullPointerException: Cannot invoke "org.springframework.cloud.netflix.eureka.CloudEurekaClient.getApplications()" because the return value of "org.springframework.cloud.netflix.eureka.serviceregistry.EurekaRegistration.getEurekaClient()" is null
at org.springframework.cloud.netflix.eureka.serviceregistry.EurekaServiceRegistry.maybeInitializeClient(EurekaServiceRegistry.java:54) ~[spring-cloud-netflix-eureka-client-3.0.0.jar:3.0.0]
at org.springframework.cloud.netflix.eureka.serviceregistry.EurekaServiceRegistry.register(EurekaServiceRegistry.java:38) ~[spring-cloud-netflix-eureka-client-3.0.0.jar:3.0.0]
at org.springframework.cloud.netflix.eureka.serviceregistry.EurekaAutoServiceRegistration.start(EurekaAutoServiceRegistration.java:83) ~[spring-cloud-netflix-eureka-client-3.0.0.jar:3.0.0]
at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:178) ~[spring-context-5.3.2.jar:5.3.2]
pom.xml 如下：
<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.4.1</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<java.version>15</java.version>
<spring-cloud.version>2020.0.0</spring-cloud.version>
</properties>
<groupId>some.group</groupId>
<artifactId>some-artefact</artifactId>
<version>1.0</version>
<name>some-name</name>
<description>some-description</description>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</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>
以下是application.yml：
spring:
application:
name: @project.artifactId@
logging:
file.name: ../logs/@project.artifactId@.log
file.max-size: 10MB
server:
port: 8080
还有主类：
@SpringBootApplication
@ComponentScan("com.something")
@EnablediscoveryClient
public class SpigaConnectorServiceApplication {
public static void main(String[] args) {
SpringApplication.run(SpigaConnectorServiceApplication.class,args);
}
@RestController
class ServiceInstanceRestController {
@Autowired
private discoveryClient discoveryClient;
@RequestMapping("/service-instances/{applicationName}")
public List<ServiceInstance> serviceInstancesByApplicationName(
@PathVariable String applicationName) {
return this.discoveryClient.getInstances(applicationName);
}
}
}
以下是服务器pom：
<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.3.7.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<java.version>15</java.version>
<spring-cloud.version>Hoxton.SR1</spring-cloud.version>
</properties>
<groupId>com.ptesa.cloud</groupId>
<artifactId>pt-eureka-server</artifactId>
<version>1.0</version>
<name>pt-eureka-server</name>
<description>Registry and discovery of services</description>
<packaging>jar</packaging>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</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>
服务器的application.yml：
server:
port: 8761
eureka:
client:
registerWithEureka: false
fetchRegistry: false
以及启动服务器的类：
@EnableEurekaServer
@SpringBootApplication
public class EurekaServerApplication {
public static void main(String[] args) {
SpringApplication.run(com.ptesa.cloud.EurekaServerApplication.class);
}
}
使用 Spring Boot 版本 2.3.7.RELEASE 时我没有这个问题。应用程序几乎正常启动。只需收到以下警告：
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by com.thoughtworks.xstream.core.util.Fields (file:/C:/Users/Jucaalpa/.m2/repository/com/thoughtworks/xstream/xstream/1.4.11.1/xstream-1.4.11.1.jar) to field java.util.TreeMap.comparator
WARNING: Please consider reporting this to the maintainers of com.thoughtworks.xstream.core.util.Fields
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
有没有办法用 Spring Boot 2.4.1 运行 Eureka 客户端。由于兼容性问题，您认为使用 Spring Boot 2.3.7 会更好吗？
谢谢。
解决方法
发现添加如下依赖，问题不存在。
<dependency>
<groupId>com.sun.jersey.contribs</groupId>
<artifactId>jersey-apache-client4</artifactId>
<version>1.19.4</version>
</dependency>
在客户端yaml文件中，添加如下配置
eureka:
client:
register-with-eureka: true
fetch-registry: true
service-url:
defaultZone: http://localhost:8761/eureka/
instance:
hostname: localhost
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