官方网是这样说的：
https://www.activiti.org/userguide/index.html#springSpringBoot
The following installation instructions are verified on Eclipse Kepler and Indigo. Note that Eclipse Helios is NOT supported.
Go to Help → Install New Software. In the following panel, click on Add button and fill in the following fields:
*Name:*Activiti BPMN 2.0 designer
*Location:*http://activiti.org/designer/update/
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这样安装，由于网络原因会经常卡死：
第二种解决方案，手动安装离线文件：
Eclipse版本：
我本人实验，验证过的：
Mac版：eclipse-jee-indigo-SR2-macosx-cocoa-x86_64
Mac版：eclipse-jee-neon-3-macosx-cocoa-x86_64
eclipse老版本indigo-3.7和最新版本neon-4.6，版本解释见下方：
http://blog.csdn.net/shenhonglei1234/article/details/55097889
安装步骤一：
百度云：
链接:https://pan.baidu.com/s/1uVbckVTD_puqf0G7x5PXpg 密码:2rbm
安装步骤二：
将下载的文件解压放到：
notes:
将activiti-designer-5.14.1内的两个文件：features和plugins放到eclipse的dropins文件内：如图：
将文件：eclipse安装activiti需装eclipse插件20170325的四个文件放到eclipse根目录的plugins内：
org.eclipse.emf.transaction_1.4.0.201306111400
org.eclipse.emf.validation_1.8.0.201403111711
org.eclipse.emf.validation.ui_1.7.0.201403111711
org.eclipse.emf.workspace_1.5.1.201306111400
为什么放：在线安装时会报：
Cannot complete the install because one or more required items could not be found.
Software being installed: Activiti Eclipse BPMN 2.0 Designer 5.14.1 (org.activiti.designer.feature.feature.group 5.14.1)
Missing requirement: Activiti Eclipse BPMN 2.0 Designer 5.14.1 (org.activiti.designer.feature.feature.group 5.14.1) requires ‘org.eclipse.emf.transaction 1.4.0’ but it could not be found
缺失插件。
安装步骤三：
上面步骤OK后，重新启动eclipse就OK了，成功后的效果：
如果你不安装缺失的四个插件，视图里不会显示Activiti文件夹，也就是说安装不成功。