springcloud与hystrix整合时freemarker依赖问题分析

山行AI

发布于 2020-02-11 13:17:44

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发布于 2020-02-11 13:17:44

文章被收录于专栏：山行AI山行AI

springcloud 整合 hystrix-dashboard 时出现报错信息，现针对问题的解决方法进行如下记录。

错误信息

freemarker.core._MiscTemplateException: Template importing failed (for parameter value "/spring.ftl"):
Syntax error in template "spring.ftl" in line 1, column 7:
Unknown FTL header parameter: output_format

----
FTL stack trace ("~" means nesting-related):
    - Failed at: #import "/spring.ftl" as spring  [in template "hystrix/index.ftl" at line 1, column 1]
----
    at freemarker.core.LibraryLoad.accept(LibraryLoad.java:64) ~[freemarker-2.3.23.jar:2.3.23]
    at freemarker.core.Environment.visit(Environment.java:324) [freemarker-2.3.23.jar:2.3.23]
    at freemarker.core.MixedContent.accept(MixedContent.java:54) [freemarker-2.3.23.jar:2.3.23]
    at freemarker.core.Environment.visit(Environment.java:324) [freemarker-2.3.23.jar:2.3.23]
    at freemarker.core.Environment.process(Environment.java:302) [freemarker-2.3.23.jar:2.3.23]
    at freemarker.template.Template.process(Template.java:325) [freemarker-2.3.23.jar:2.3.23]
    at org.springframework.web.servlet.view.freemarker.FreeMarkerView.processTemplate(FreeMarkerView.java:389) [spring-webmvc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.springframework.web.servlet.view.freemarker.FreeMarkerView.doRender(FreeMarkerView.java:302) [spring-webmvc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.springframework.web.servlet.view.freemarker.FreeMarkerView.renderMergedTemplateModel(FreeMarkerView.java:253) [spring-webmvc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.springframework.web.servlet.view.AbstractTemplateView.renderMergedOutputModel(AbstractTemplateView.java:178) [spring-webmvc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:316) [spring-webmvc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1371) [spring-webmvc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1117) [spring-webmvc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1056) [spring-webmvc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942) [spring-webmvc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005) [spring-webmvc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:897) [spring-webmvc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882) [spring-webmvc-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) [tomcat-embed-websocket-9.0.24.jar:9.0.24]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) [spring-web-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:118) [spring-web-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:92) [spring-web-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:118) [spring-web-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93) [spring-web-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:118) [spring-web-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200) [spring-web-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:118) [spring-web-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:526) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:860) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1587) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_121]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_121]
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.24.jar:9.0.24]
    at java.lang.Thread.run(Thread.java:745) [na:1.8.0_121]
Caused by: freemarker.core.ParseException: Syntax error in template "spring.ftl" in line 1, column 7:
Unknown FTL header parameter: output_format
    at freemarker.core.FMParser.HeaderElement(FMParser.java:3374) ~[freemarker-2.3.23.jar:2.3.23]
    at freemarker.core.FMParser.Root(FMParser.java:3428) ~[freemarker-2.3.23.jar:2.3.23]
    at freemarker.template.Template.<init>(Template.java:208) [freemarker-2.3.23.jar:2.3.23]
    at freemarker.cache.TemplateCache.loadTemplate(TemplateCache.java:495) ~[freemarker-2.3.23.jar:2.3.23]
    at freemarker.cache.TemplateCache.getTemplate(TemplateCache.java:409) ~[freemarker-2.3.23.jar:2.3.23]
    at freemarker.cache.TemplateCache.getTemplate(TemplateCache.java:261) ~[freemarker-2.3.23.jar:2.3.23]
    at freemarker.template.Configuration.getTemplate(Configuration.java:1786) ~[freemarker-2.3.23.jar:2.3.23]
    at freemarker.core.Environment.getTemplateForInclusion(Environment.java:2044) [freemarker-2.3.23.jar:2.3.23]
    at freemarker.core.Environment.getTemplateForInclusion(Environment.java:1993) [freemarker-2.3.23.jar:2.3.23]
    at freemarker.core.Environment.getTemplateForImporting(Environment.java:2112) [freemarker-2.3.23.jar:2.3.23]
    at freemarker.core.LibraryLoad.accept(LibraryLoad.java:62) ~[freemarker-2.3.23.jar:2.3.23]

乍一看，是 freemarker 解析的问题，但是所有的依赖都是正常情况下处理的，没有头绪。

解决方式

最先想到的是版本依赖的问题，于是查看 pom 依赖信息如下:

<parent>
        <artifactId>AA-Platform</artifactId>
        <groupId>com.aa</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>AA-Hystrix</artifactId>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>com.netflix.hystrix</groupId>
            <artifactId>hystrix-javanica</artifactId>
            <version>RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-netflix-hystrix-dashboard</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-hystrix</artifactId>
        </dependency>
    </dependencies>

依赖树的信息如下:

看到这里仍然没有头绪，因为像 freemarker 和 hystrix 的依赖都不缺少，也没有重复依赖，看不出依赖冲突。

后来突然想到在 eureka 的 server 端也有用到 freemarker 的情况，赶紧查看它的 pom 依赖如下:

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>AA-EurekaService</artifactId>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Greenwich.SR3</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </dependency>

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

它的依赖树为:

仔细比对，发现 spring-boot-starter-freemarker 的版本及 freemarker 的版本是不同的，在 AA-Hystrix 工程中 freemarker 的依赖为 2.3.23，但是在 AA-EurekaService 工程中 freemarker 的依赖为 2.3.29，于是在 AA-Hystrix 项目中将 freemarker 的依赖版本替换成 2.3.29(排除低版本的依赖，重新引入高版本的依赖)，问题解决。

虽然问题解决了，但是还是存在很大的疑惑。

具体分析

为什么在同一个父工程中，两个子 Module 表现出的版本依赖不一致？

我们先来看下整个 AA 项目的父 pom 中的依赖，这里我们只列举与本文相关的主要依赖:

<properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <spring.boot.parent.version>2.1.8.RELEASE</spring.boot.parent.version>
         <freemarker.version>2.3.23</freemarker.version>
  </properties>

<dependencyManagement>
 <dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-dependencies</artifactId>
    <version>Greenwich.SR3</version>
    <type>pom</type>
    <scope>import</scope>
</dependency>
 <dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>${spring.boot.parent.version}</version>
    <type>pom</type>
    <scope>import</scope>
</dependency>
</dependencyManagement>
 <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>

由 pom 可以看出，父 pom 中 spring-boot-starter-parent 的依赖版本号为 2.1.8.RELEASE，spring-cloud-dependencies 的依赖版本为 Greenwich.SR3 对应的版本号为 2.1.3.RELEASE

因为在 AA-EurekaService 只依赖了父 pom 的 spring-boot-starter，没有依赖父 pom 的 dependencyManagement 中的其他依赖(如 freemarker 的依赖)。它的 parent 为:

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

因为依赖了外层 pom 的 spring-boot-statrer 的 2.1.8.RELEASE 版本，所以它的 spring-boot-starter-freemarker 的依赖是 2.1.8.RELEASE，但是它 freemarker 的依赖是由 2.1.8.RELEASE 版本的 spring-boot-starter-freemarker 依赖的 2.3.29 版本。

而在 AA-Hystrix 项目中，完全继承了父 pom，包括 freemarker 的版本，所以依赖的 freemarker 为父 pom 的 dependencyManagement 中配置的 2.3.23 版本。

究其原因是这是一个组内关于 springcloud 的试验性项目，很多 module 为不同成员创建，没有按父 module 规范处理，从而引起了依赖配置的混乱。而关于 freemarker 的版本问题则是对 springboot 进行升级后，一些对应的依赖包也需要进行升级，否则就会出现问题。

最后的解决方法

父 pom 修改

将父 pom 中的 freemarker 版本号修改成 2.3.29

AA-EurekaService 的修改

pom 中的 parent 修改成如下:

<parent>
        <artifactId>AA-Platform</artifactId>
        <groupId>com.aa</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>

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原始发表：2020-01-02，如有侵权请联系 cloudcommunity@tencent.com 删除

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