faq compatibility

三方软件升级

迁移框架通常都会涉及三方件升级和兼容问题处理。因为早期的框架由于很久没有更新，依赖了很多老的三方件，而迁移的目标框架一般会选择比较稳定、社区持续维护 和发展的版本。

解决三方件冲突有一些通用的策略：比如尽可能使用新版本替换老版本，采用 dependency management 管理依赖等。 可以参考 三方软件版本管理策略及冲突解决 。

• xml-apis版本过低

报错如下：

Caused by: java.lang.NoClassDefFoundError: org/w3c/dom/ElementTraversal
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:468)

问题原因为xml-apis版本过低，可以在 dependency management 中约定其版本， 如果在 dependency 中直接引用并指定了版本，可以删除版本号。

<dependencyManagement>
  <dependencies>
    // others
    <dependency>
      <groupId>xml-apis</groupId>
      <artifactId>xml-apis</artifactId>
      <version>1.4.01</version>
    </dependency>
  </dependencies>
</dependencyManagement>

<dependencies>
    // others
    <dependency>
        <groupId>xml-apis</groupId>
        <artifactId>xml-apis</artifactId>
    </dependency>
</dependencies>

• Spring升级CrossOrigin行为变化

报错信息如下：

Caused by: java.lang.IllegalArgumentException: When allowCredentials is true, allowedOrigins cannot contain the special value "*" since that cannot be set on the "Access-Control-Allow-Origin" response header. To allow credentials to a set of origins, list them explicitly or consider using "allowedOriginPatterns" instead.
at org.springframework.web.cors.CorsConfiguration.validateAllowCredentials(CorsConfiguration.java:473) ~[spring-web-5.3.9.jar!/:5.3.9]
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping$MappingRegistry.register(AbstractHandlerMethodMapping.java:646) ~[spring-webmvc-5.3.9.jar!/:5.3.9]
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.registerHandlerMethod(AbstractHandlerMethodMapping.java:328) ~[spring-webmvc-5.3.9.jar!/:5.3.9]

需要显示的设置CrossOrigin的originPatterns属性，比如：

@CrossOrigin(allowCredentials = "true", allowedHeaders = "*", originPatterns = "*")

• thymeleaf安全加固限制问题

thymeleaf升级后，做了很多安全增强，有些功能不可用， 报错内容：

2021-10-21 01:08:55,655 ERROR TemplateEngine:1136-[THYMELEAF][http-nio-8091-exec-1] Exception processing template "login": An error happened during template parsing (template: "class path resource [template/login.html]")
org.thymeleaf.exceptions.TemplateInputException: An error happened during template parsing (template: "class path resource [template/login.html]")
at org.thymeleaf.templateparser.markup.AbstractMarkupTemplateParser.parse(AbstractMarkupTemplateParser.java:241) ~[thymeleaf-3.0.12.RELEASE.jar!/:3.0.12.RELEASE]

解决方案，详情参考：stackoverflow 和 thymeleaf

• guava版本过低，导致不兼容问题

报错信息：

2021-10-18 12:36:20,072 WARN LocalCache:2290 -Exception thrown during refresh
java.util.concurrent.ExecutionException: java.lang.NoSuchMethodError: com.google.common.util.concurrent.Futures.submit(Ljava/util/concurrent/Callable;Ljava/util/concurrent/Executor;)Lcom/google/common/util/concurrent/ListenableFuture;

，可以在 dependency management 中约定其版本， 如果在 dependency 中直接引用并指定了版本，可以删除版本号。

<dependencyManagement>
  <dependencies>
    // others
    <dependency>
      <groupId>com.google.guava</groupId>
      <artifactId>guava</artifactId>
      <version>30.0-jre</version>
    </dependency>
  </dependencies>
</dependencyManagement>

<dependencies>
    // others
    <dependency>
      <groupId>com.google.guava</groupId>
      <artifactId>guava</artifactId>
    </dependency>
</dependencies>

• guava 和 google-connections 包含相同的类

报错信息：

Description:
An attempt was made to call a method that does not exist. The attempt was made from the following location:
com.google.common.cache.CacheBuilder.getKeyStrength(CacheBuilder.java:529)
The following method did not exist: com.google.common.base.Objects.firstNonNull(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;
The method's class, com.google.common.base.Objects, is available from the following locations: jar:file:/D:/BASA_maven/com/google/collections/google-collections/1.0/google-collections-1.0.jar!/com/google/common/base/Objects.class jar:file:/D:/BASA_maven/com/google/guava/guava/16.0.1/guava-16.0.1.jar!/com/google/common/base/Objects.class
The class hierarchy was loaded from the following locations:
com.google.common.base.Objects: file:/D:/BASA_maven/com/google/collections/google-collections/1.0/google-collections-1.0.jar
Action:
Correct the classpath of your application so that it contains a single, compatible version of com.google.common.base.Objects

解决方案：

删除google-collections依赖，guava使用新版本。google-collections已经很久不维护，不能使用，相关功能已经合并到guava中。