运行Maven工程总是报错:No goals have been specified for this build

No goals have been specified for this build. You must specify a valid lifecycle 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, process-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-clean, clean, post-clean, pre-site, site, post-site, site-deploy. -> [Help 1]