Problems setting up Maven [duplicate]

问题:

This question already has an answer here:

• Adding directory to PATH Environment Variable in Windows 16 answers

I am having difficulties installing Maven.

I have set all the enviromental variables according to this: http://maven.apache.org/download.html

Although I am using windows 7, when I try and run the command mvn --version, I get, mvn is not recognized as an internal or external command etc.

When I run it from within src\bin, I get the error:

Exception in thread "main" java.lang.ClassNotFoundException: org.codehaus.plexus.classworlds.launcher.Launcher 
at java.net.URLClassLoader$1.run<URLClassLoader.java:202>
at java.security.AccessController.doPrivleged(Native Method) 
...etc

then:

Could not find the main class: org.codehaus.plexus.classworlds.launcher.Launcher.

回答1:

Check that you don't have an M2_HOME environment variable.

回答2:

I ended up on this question with the same problem, however, I had committed an elementary mistake of downloading the apache-maven-..*-src.zip instead of the apache-maven-..*-bin.zip

Once I realised that mistake, it was smooth sailing as soon as I corrected it. I suppose the instructions on the download page should be more than adequate

回答3:

All you should need to do to install and use maven:

1) Download maven 3. The ZIP should be fine. Install it in a known place; I use c:\tools\ as the parent directory but your mileage may vary.

2) Set your PATH to point to the bin directory in the installation directory. If Maven is in c:\tools\maven-3.0.3 (as it is on my system), you'd add c:\tools\maven-3.0.3\bin to PATH:

set PATH=%PATH%;c:\tools\maven-3.0.3

You may also want to set MVN_HOME:

set MVN_HOME=c:\tools\maven-3.0.3

3) start a new command shell (cmd.exe). mvn should work; if not, you've skipped something here or something's badly wrong in your configuration.

回答4:

blanking out M2_HOME worked for me on Ubuntu. Can test with just: 'export M2_HOME='

回答5:

Your first problem is because you do not have maven in your PATH. The second problem is what I had. I had both Maven 2 and 3 on my computer and even though I removed Maven 2 links from my PATH, it was still interfering with my new Maven.

You need to remove or rename the system variable M2_HOME. 1. Right click My Computer -> Properties 2. Advanced system settings 3. Environment Variables 4. Rename or delete M2_HOME

回答6:

I setup M2_HOME like this:

export M2_HOME="~/app/apache-maven-3.1.1"

and saw the same exception:

Exception in thread "main" java.lang.ClassNotFoundException: org.codehaus.plexus.classworlds.launcher.Launcher`. 

I changed to use absolute path and it worked:

export M2_HOME="Users/myaccount/app/apache-maven-3.1.1"

In my case, the M2_HOME env variable wasn't the problem. I think that java and/or mvn startup script doesn't expand the tilde in classpath cmd line args.

回答7:

I got the same error

In my case configuration which generate error

export M2_HOME="/home/ashoka/apache-maven-3.0.4/bin/"

PATH=$M2_HOME/bin:$PATH

Working configuration

export M2_HOME="/home/ashoka/apache-maven-3.0.4/"

PATH=$M2_HOME/bin:$PATH

Ashok Kumara

回答8:

"mvn is not recognized as an internal or external command etc." means you haven't set your environment variable in windows. Read the whole http://maven.apache.org/download.html :-)

回答9:

Do you have maven 2 also installed? I found one link in searching, see if it helps http://blogs.oracle.com/sreekanth/entry/java_lang_noclassdeffounderror_org_codehaus

and also double check your environment variables to make sure you have set all the variables mentioned in the doc.

For this error "mvn is not recognized as an internal or external command", add src/bin folder in 'path' environment variable.

回答10:

Like Joseph Ottinger said, you have to put Maven installation directory to your PATH environment variables or User variables. You can edit user variables by running command "rundll32 sysdm.cpl,EditEnvironmentVariables" without quotes.

First add new variable called MAVEN_HOME and for it's value Mavens installation directory ie. c:\tools\maven-3.0.3\ then edit PATH variable and add end of the value ;%MAVEN_HOME%\bin (notice semicolon)

After re-login or opening new command prompt mvn command should work perfectly.

回答11:

Some people seem to have trouble with adding Maven bin folders to the System PATH vs the User PATH. You could try defining your environment under your User variables, but this would be more of a workaround than a solution.

PATH=%PATH%;%JAVA_HOME%\bin;%JRE_HOME%\bin;%MAVEN_HOME%\bin

You can diagnose these access errors with Rapid Environment Editor, which will tell you if certain PATH locations are invalid or inaccessible to you.

回答12:

This is a question from long ago but recently i encountered this problem. In my case it was because i had M2_HOME set from a previous installation from months ago. I just unset the variable and after that was good to go.