The import org.apache.commons cannot be resolved i

问题:

I having the problem while compiling the my project in eclipse. It was shoving the error The import org.apache.commons cannot be resolved.

Please anyone tell me what does this error tells. and how to solve it.

回答1:

The mentioned package/classes are not present in the compiletime classpath. Basically, Java has no idea what you're talking about when you say to import this and that. It can't find them in the classpath.

It's part of Apache Commons FileUpload. Just download the JAR and drop it in /WEB-INF/lib folder of the webapp project and this error should disappear. Don't forget to do the same for Apache Commons IO, that's where FileUpload depends on, otherwise you will get the same problem during runtime.

---

Unrelated to the concrete problem, I see that you're using Tomcat 7, which is a Servlet 3.0 compatible container. Do you know that you can just use the new request.getPart() method to obtain the uploaded file without the need for the whole Commons FileUpload stuff? Just add @MultipartConfig annotation to the servlet class so that you can use it. See also How to upload files to server using JSP/Servlet?

回答2:

If you got a Apache Maven project, it's easy to use this package in your project. Just specify it in your pom.xml:

<project>
...

    <properties>
        <version.commons-io>2.4</version.commons-io>
    </properties>

    <dependencies>
        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>${version.commons-io}</version>
        </dependency>
    </dependencies>

...
</project>

回答3:

You could just add one needed external jar file to the project. Go to your project-->java build path-->libraries, add external JARS.Then add your downloaded file from the formal website. My default name is commons-codec-1.10.jar

回答4:

expand "Java Resources" and then 'Libraries' (in eclipse project). make sure that "Apache Tomcat" present.

if not follow- right click on project -> "Build Path" -> "Java Build Path" -> "Add Library" -> select "Server Runtime" -> next -> select "Apache Tomcat -> click finish

回答5:

Look for "poi-3.17.jar"!!!

1. Download from "https://poi.apache.org/download.html".
2. Click the one Binary Distribution -> poi-bin-3.17-20170915.tar.gz
3. Unzip the file download and look for this "poi-3.17.jar".

Problem solved and errors disappeared.