解决办法1:
重启就行了。
解决办法2:
添加vm参数
-startup
plugins/org.eclipse.equinox.launcher_1.2.0.v20110502.jar
--launcher.library
plugins/org.eclipse.equinox.launcher.win32.win32.x86_1.1.100.v20110502
-product
org.eclipse.epp.package.jee.product
--launcher.defaultAction
openFile
--launcher.XXMaxPermSize
256M
-showsplash
org.eclipse.platform
--launcher.XXMaxPermSize
256m
--launcher.defaultAction
openFile
-vm
C:\Program Files\Java\jdk1.6.0_23\bin\javaw.exe
-vmargs
-Dosgi.requiredJavaVersion=1.5
-Xms40m
-Xmx512m