目录简介角色类图代码简介 使多个对象都有机会处理请求，从而避免请求的发送者和接收者之间的耦合关系。将这些对象连成一条链，并沿着这条链传递该请求，直到有一个对象处理它为止。
Currrently, all the topics that are listed in http://help.eclipse.org/galileo/index.jsp are not installed on my machine. I understand that help is only installed for the plugins that are installed alr
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