解决Eclipse无法安装STS

使用Eclipse Neon安装Spring Tool Suite报错：

Cannot complete the install because one or more required items could not be found.
  Software being installed: Spring IDE OSGi Extension (optional) 3.8.3.201612191259-RELEASE (org.springframework.ide.eclipse.osgi.feature.feature.group 3.8.3.201612191259-RELEASE)
  Missing requirement: Spring IDE Live Beans Graph 3.8.3.201612191259-RELEASE (org.springframework.ide.eclipse.beans.ui.livegraph 3.8.3.201612191259-RELEASE) requires 'bundle org.eclipse.zest.core [1.0.0,2.0.0)' but it could not be found
  Cannot satisfy dependency:
    From: Spring IDE Core (required) 3.8.3.201612191259-RELEASE (org.springframework.ide.eclipse.feature.feature.group 3.8.3.201612191259-RELEASE)
    To: org.springframework.ide.eclipse.beans.ui.livegraph [3.8.3.201612191259-RELEASE]
  Cannot satisfy dependency:
    From: Spring IDE OSGi Extension (optional) 3.8.3.201612191259-RELEASE (org.springframework.ide.eclipse.osgi.feature.feature.group 3.8.3.201612191259-RELEASE)
    To: org.springframework.ide.eclipse.feature.feature.group 0.0.0

原因是没有安装STS依赖的GEF插件
解决办法：

启动eclipse，点击window——>preferences——>install/update——>available software sites，点击Add
添加如下信息：
GEF

http://download.eclipse.org/tools/gef/updates/releases/
安装GEF插件

然后再重新安装sts插件

以 Luna 为例，点击 Help→Install New Software...→Available Software Sites 可以看到所有的更新源，将其中的download.eclipse.org全部替换成mirrors.ustc.edu.cn/eclipse即可。

当我们观察但Eclipse到download.eclipse.org下载插件时，

我们就关闭此次下载，做如上修改，再继续下载，这样反复几次就可以下载成功了。

参考：

http://forum.spring.io/forum/spring-projects/springsource-tool-suite/121775-cannot-install-spring-tool-suite-sts-for-eclipse-juno-3-8-4-2-3-1-0-release

http://stackoverflow.com/questions/14068135/spring-ide-installation-error

http://www.xie4ever.com/2016/12/08/eclipse%E6%97%A0%E6%B3%95%E5%AE%89%E8%A3%85sts%E6%8F%92%E4%BB%B6%E7%9A%84%E9%97%AE%E9%A2%98/