第一次打開項目報白頁，第二次突然就啓動不了了，而且控制檯報錯如下：
Description:
Failed to configure a DataSource: ‘url’ attribute is not specified and no embedded datasource could be configured.
Reason: Failed to determine a suitable driver class
Action:
Consider the following:
If you want an embedded database (H2, HSQL or Derby), please put it on the classpath.
If you have database settings to be loaded from a particular profile you may need to activate it (no profiles are currently active).
找了很久的原因，發現是pom.xml的project總是報紅線。先clean一下，然後install，發現有個jar包有問題
然後打開本地maven倉庫，把其他版本的jar包刪掉，把2.1.9版本里面的文件都刪掉，重新download一下，發現果然有問題，只下載了一個xxxxxpom.lastUpdated.在網上找一下jar包，把jar包更換一下再次打開項目，就不報錯了，同時也不報白頁了。