Maven编译器插件始终将一组源检测为“陈旧”

Question

修正：这是maven-compiler-plugin
3.1中的一个已知错误

我正在将1000+ java-sources项目的基于ant的版本转换为maven。到目前为止还不错，但是每次启动时mvn compile它都会重新编译所有内容（而不是重用旧类）

使用的mvn -X compile报告

[DEBUG] Stale source detected: /project_path/src/main/java/package_path/AFile1.java
[DEBUG] Stale source detected: /project_path/src/main/java/package_path/AFile2.java
...

（ 仅适用于某个程序包中的文件， 可能未从其余代码中引用该文件；不适用于我的源代码，我只是在尝试弄乱该版本）

编译不会失败，并且会在以下时间生成带有更新时间戳记的类

/project_path/target/classes/package_path/AFile1.class
/project_path/target/classes/package_path/AFile2.class
...

但是，在查看时间戳时，java文件自昨天以来没有更改，并且类文件是最新的。为什么这些资源被确定为陈旧？如何调试此问题？

即使没有发生任何更改，也必须重新编译1k +个文件，这是一个麻烦…

样本输出：

$ mvn clean compile
[INFO] Scanning for projects...
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building MyProject 1.9.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[WARNING] The POM for net.sourceforge:jffmpeg:jar:1.1.0 is missing, no dependency information available
[INFO] 
[INFO] --- maven-clean-plugin:2.4.1:clean (default-clean) @ my-project ---
[INFO] Deleting /project_path/target
[INFO] 
[INFO] --- maven-resources-plugin:2.5:resources (default-resources) @ my-project ---
[debug] execute contextualize
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /project_path/src/main/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ my-project ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1162 source files to project_path/target/classes
....
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 11.215s
[INFO] Finished at: Tue Jul 30 12:42:25 CEST 2013
[INFO] Final Memory: 25M/429M
[INFO] ------------------------------------------------------------------------



$ mvn compile
[INFO] Scanning for projects...
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building MyProject 1.9.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[WARNING] The POM for net.sourceforge:jffmpeg:jar:1.1.0 is missing, no dependency information available
[INFO] 
[INFO] --- maven-resources-plugin:2.5:resources (default-resources) @ my-project ---
[debug] execute contextualize
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /project_path/src/main/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ my-project ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1162 source files to /project_path/target/classes
... 
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 12.140s
[INFO] Finished at: Tue Jul 30 12:42:44 CEST 2013
[INFO] Final Memory: 22M/379M
[INFO] ------------------------------------------------------------------------

Answer 1

这是maven-compiler-plugin
3.1中的一个已知问题。正在https://issues.apache.org/jira/browse/MCOMPILER-209（该useIncrementalCompilation标志已损坏）中对其进行跟踪。

该问题与另一个3.1错误无关，https：//issues.apache.org/jira/browse/MCOMPILER-205（其中不产生.class输出的文件始终标记为“陈旧”）。

经过进一步测试，回到3.0并没有真正解决问题（它仅在下一个版本中才有效mvn clean compile。但是，正如Michael
Lemke在评论中建议的那样，标记useIncrementalCompilation为false是可行的替代品；现在，每次仅重新编译有问题的软件包（相反，整个代码库）。