如何修复“导入 org.apache.poi 无法解析”

Question

我想在我的代码中使用 Apache-POI，但在导入语句中收到错误消息 The import org.apache.poi cannot be resolved import org.apache.poi.xssf.usermodel.XSSFWorkbook;

我是新手，刚安装了 Visual Studio Code v1.30.2、Maven 3.6.0、Java JRE 1.8.0_201。

我已经激活了以下扩展：Java 调试器、0.16.0 Java 依赖查看器、0.3.0 Java 扩展包、0.5.0 Java 测试运行器、0.14.0 Java ™ 语言支持、0.37.0 Java Maven， 0.14.0

我在依赖部分的 pom.xml 中输入了这些语句：

 <!-- https://mvnrepository.com/artifact/org.apache.poi/poi-->
<dependency>
    <groupId>org.apache.poi</groupId>
    <artifactId>poi</artifactId>
    <version>4.0.1</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.apache.poi/poi-ooxml -->
<dependency>
    <groupId>org.apache.poi</groupId>
    <artifactId>poi-ooxml</artifactId>
    <version>4.0.1</version>
</dependency>

我也尝试过其他 POI 版本，例如 3.10-FINAL。

我对 Java、Maven 和 VSCode 太陌生了，无法确保我已经包含了指向解决方案的所有必要信息。请帮我 ：）

我运行了 mvn compile ，结果如下：

 C:\Users\MYUSERNAME\Documents\Java\project2>mvn compile
[INFO] Scanning for projects...
[INFO]
[INFO] ---------------------< MYNAME.project2:project2 >---------------------
[INFO] Building project2 1.0-SNAPSHOT
[INFO] --------------------------------[ jar ]---------------------------------
[INFO]
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ project2 ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory C:\Users\MYUSERNAME\Documents\Java\project2\src\main\resources
[INFO]
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ project2 ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to C:\Users\MYUSERNAME\Documents\Java\project2\target\classes
[INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR :
[INFO] -------------------------------------------------------------
[ERROR] /C:/Users/MYUSERNAME/Documents/Java/project2/src/main/java/MYNAME/project2/App.java:[12,1] package org.apache.poi.ss.usermodel does not exist
[ERROR] /C:/Users/MYUSERNAME/Documents/Java/project2/src/main/java/MYNAME/project2/App.java:[13,37] package org.apache.poi.xssf.usermodel does not exist
[ERROR] /C:/Users/MYUSERNAME/Documents/Java/project2/src/main/java/MYNAME/project2/App.java:[14,37] package org.apache.poi.xssf.usermodel does not exist
[ERROR] /C:/Users/MYUSERNAME/Documents/Java/project2/src/main/java/MYNAME/project2/App.java:[46,9] cannot find symbol
  symbol:   class XSSFWorkbook
  location: class MYNAME.project2.App
[ERROR] /C:/Users/MYUSERNAME/Documents/Java/project2/src/main/java/MYNAME/project2/App.java:[46,45] cannot find symbol
  symbol:   class XSSFWorkbook
  location: class MYNAME.project2.App
[ERROR] /C:/Users/MYUSERNAME/Documents/Java/project2/src/main/java/MYNAME/project2/App.java:[48,9] cannot find symbol
  symbol:   class XSSFSheet
  location: class MYNAME.project2.App
[ERROR] /C:/Users/MYUSERNAME/Documents/Java/project2/src/main/java/MYNAME/project2/App.java:[55,13] cannot find symbol
  symbol:   method setCellValue(java.lang.String)
  location: variable cell of type com.google.common.collect.Table.Cell
[INFO] 7 errors
[INFO] -------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  5.549 s
[INFO] Finished at: 2019-01-30T09:41:45+01:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project project2: Compilation failure: Compilation failure:
[ERROR] /C:/Users/MYUSERNAME/Documents/Java/project2/src/main/java/MYNAME/project2/App.java:[12,1] package org.apache.poi.ss.usermodel does not exist
[ERROR] /C:/Users/MYUSERNAME/Documents/Java/project2/src/main/java/MYNAME/project2/App.java:[13,37] package org.apache.poi.xssf.usermodel does not exist
[ERROR] /C:/Users/MYUSERNAME/Documents/Java/project2/src/main/java/MYNAME/project2/App.java:[14,37] package org.apache.poi.xssf.usermodel does not exist
[ERROR] /C:/Users/MYUSERNAME/Documents/Java/project2/src/main/java/MYNAME/project2/App.java:[46,9] cannot find symbol
[ERROR]   symbol:   class XSSFWorkbook
[ERROR]   location: class MYNAME.project2.App
[ERROR] /C:/Users/MYUSERNAME/Documents/Java/project2/src/main/java/MYNAME/project2/App.java:[46,45] cannot find symbol
[ERROR]   symbol:   class XSSFWorkbook
[ERROR]   location: class MYNAME.project2.App
[ERROR] /C:/Users/MYUSERNAME/Documents/Java/project2/src/main/java/MYNAME/project2/App.java:[48,9] cannot find symbol
[ERROR]   symbol:   class XSSFSheet
[ERROR]   location: class MYNAME.project2.App
[ERROR] /C:/Users/MYUSERNAME/Documents/Java/project2/src/main/java/MYNAME/project2/App.java:[55,13] cannot find symbol
[ERROR]   symbol:   method setCellValue(java.lang.String)
[ERROR]   location: variable cell of type com.google.common.collect.Table.Cell
[ERROR] -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/

我还在 此处 粘贴了 mvn -X compile 的完整输出

我把我的完整的 POM.XML 粘贴 在这里

在我的本地文件夹 C:\Users\MYUSERNAME.m2\repository\org\apache 中 没有子文件夹 poi。

原文由 T C 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 1

感谢所有贡献者，尤其是@ayZagen（他向我指出了 pom.xml）。

事实证明，我已经将 poi 的依赖项插入到的依赖项部分

        <pluginManagement>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-checkstyle-plugin</artifactId>

而不是进入正确的部分 <project> <dependencies> 。

当 我将我的依赖项移动到正确的部分 时，maven 会下载 POI 并且该部分代码会编译。

很抱歉因为一个小错误占用了大家的时间。感谢您帮助我找出答案并提出正确的问题！这是一次非常积极的经历！

原文由 T C 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 2

根据错误日志，有两种可能性

1. 网络问题。 Maven 无法从其存储库下载 jar 文件，因此 .m2 文件夹中没有 POI 库

解决方案：检查网络/互联网。 2. 文件损坏。如果文件损坏，就会发生这种情况。

解决方案：删除 .m2 文件夹中的文件夹 org.apache.poi 。右键单击项目（来自 Eclipse） –> Maven –> Update project 。

然后 clean ＆ refresh 项目，然后运行命令 Maven clean install

原文由 TheSprinter 发布，翻译遵循 CC BY-SA 4.0 许可协议