解決一些Springboot啟動報錯問題
阿新 • • 發佈：2018-12-14
專案啟動報錯比調bug更加難受
概要：近日在學習Springcloud微服務。配置服務註冊中心，一切妥妥當當，但還是報了一個讓我崩潰的問題：org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat
翻譯一下這句話：啟動內建tomcat失敗。
具體報錯資訊如下：
org.springframework.context.ApplicationContextException: Unable to start web server; nested exception is org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:155) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE] at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:544) ~[spring-context-5.0.6.RELEASE.jar:5.0.6.RELEASE] at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE] at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE] at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:395) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:327) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1255) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1243) [spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE] at com.ecjtu.demo.DemoApplication.main(DemoApplication.java:15) [classes/:?] Caused by: org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.initialize(TomcatWebServer.java:126) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE] at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.<init>(TomcatWebServer.java:86) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE] at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getTomcatWebServer(TomcatServletWebServerFactory.java:409) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE] at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getWebServer(TomcatServletWebServerFactory.java:174) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE] at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.createWebServer(ServletWebServerApplicationContext.java:179) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE] at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:152) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE] ... 8 more Caused by: java.lang.IllegalStateException: StandardEngine[Tomcat].StandardHost[localhost].TomcatEmbeddedContext[] failed to start at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.rethrowDeferredStartupExceptions(TomcatWebServer.java:172) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE] at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.initialize(TomcatWebServer.java:110) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE] at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.<init>(TomcatWebServer.java:86) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE] at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getTomcatWebServer(TomcatServletWebServerFactory.java:409) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE] at org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory.getWebServer(TomcatServletWebServerFactory.java:174) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE] at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.createWebServer(ServletWebServerApplicationContext.java:179) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE] at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:152) ~[spring-boot-2.0.2.RELEASE.jar:2.0.2.RELEASE] ... 8 more
出了錯，當然得去看配置檔案application.yml，pom.xml,程式入口類。這三個。我們一個一個來看。
- application.yml(application.properties)
極其簡單的配置，但是跑起來不是問題。
- 程式入口類
當然也是沒有問題的，就是加了一個@EnableEurekaServer註解，表示是一個服務註冊中心
- pom.xml 放在最後不是沒道理的
<?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.ecjtu</groupId> <artifactId>demo</artifactId> <version>0.01-SNAPSHOT</version> <packaging>jar</packaging> <name>demo</name> <!--<url>http://www.example.com</url>--> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <spring-cloud.version>Finchley.SR1</spring-cloud.version> </properties> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.0.2.RELEASE</version> <relativePath/> </parent> <dependencies> <dependency> <groupId>org.springframework.cloud</groupId> <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId> <exclusions> <exclusion> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-logging</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-log4j2</artifactId> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.12</version> <scope>test</scope> </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> <!-- 下面的配置有些是額外加的，無需在意--!> build> <finalName>demo</finalName> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> <configuration> <jvmArguments> -server -Xmx2048m -Xms2048m -XX:MaxPermSize=512m -Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=9090 </jvmArguments> <mainClass>com.lelian.Application</mainClass> <fork>true</fork> </configuration> </plugin> </plugins> </build> </project>
我是左看右看，就是解決不了，但是如果我把@EnableEurekaServer註解和關於eureka的配置都去掉，就完全是一個普通的Springboot專案，但是專案可以跑起來。我也是很奇怪啊！！！ 最後想了一下是不是java版本的問題，網上許多教程都是在java8的環境下搭建的，但是我用的java版本是java10，這是一個你知道但是不知道他有什麼特性的版本，然後百度了一下他的特性，從java9開始，模組化的概念使得JAXB預設沒有載入；jaxb-api是存在jdk中的，只是預設沒有載入而已，我們需要手動引入。要問這個jaxb-api是什麼作用，大家可以自行百度，反正我引入了這個模組問題得到了解決。
jaxb模組引用 - start
<dependency>
<groupId>com.sun.xml.bind</groupId>
<artifactId>jaxb-core</artifactId>
<version>2.2.11</version>
</dependency>
<dependency>
<groupId>javax.xml.bind</groupId>
<artifactId>jaxb-api</artifactId>
</dependency>
<dependency>
<groupId>com.sun.xml.bind</groupId>
<artifactId>jaxb-impl</artifactId>
<version>2.2.11</version>
</dependency>
<dependency>
<groupId>org.glassfish.jaxb</groupId>
<artifactId>jaxb-runtime</artifactId>
<version>2.2.10-b140310.1920</version>
</dependency>
<dependency>
<groupId>javax.activation</groupId>
<artifactId>activation</artifactId>
<version>1.1.1</version>
</dependency>
jaxb模組引用 - end
最終，專案跑起來了。
