maven:cmd中运行mvn 报错？

C:\Users\Administrator>mvn

[INFO] Scanning for projects...

[INFO] ------------------------------------------------------------------------

[INFO] BUILD FAILURE

[INFO] ------------------------------------------------------------------------

[INFO] Total time: 0.287s

[INFO] Finished at: Tue Sep 17 15:31:47 CST 2013

[INFO] Final Memory: 2M/15M

[INFO] ------------------------------------------------------------------------

[ERROR] No goals have been specified for this build. You must specify a valid li

fecycle phase or a goal in the format <plugin-prefix>:<goal> or <plugin-group-id

>:<plugin-artifact-id>[:<plugin-version>]:<goal>. Available lifecycle phases are

: validate, initialize, generate-sources, process-sources, generate-resources, p

rocess-resources, compile, process-classes, generate-test-sources, process-test-

sources, generate-test-resources, process-test-resources, test-compile, process-

test-classes, test, prepare-package, package, pre-integration-test, integration-

test, post-integration-test, verify, install, deploy, pre-site, site, post-site,

 site-deploy, pre-clean, clean, post-clean. -> [Help 1]

[ERROR]

[ERROR] To see the full stack trace of the errors, re-run Maven with the -e swit

ch.

[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 rea

d the following articles:

[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/NoGoalSpecifie

dException