struts 2 result的type值解释
chain??????
??? 用来处理Action链，被跳转的action中仍能获取上个页面的值，如request信息。??????
??? com.opensymphony.xwork2.ActionChainResult??????
dispatcher??????
??? 用来转向页面，通常处理JSP??????
??? org.apache.struts2.dispatcher.ServletDispatcherResult??????
freemaker??????
??? 处理FreeMarker模板??????
??? org.apache.struts2.views.freemarker.FreemarkerResult??????
httpheader??????
??? 控制特殊HTTP行为的结果类型??????
??? org.apache.struts2.dispatcher.HttpHeaderResult???
stream??????
??? 向浏览器发送InputSream对象，通常用来处理文件下载，还可用于返回AJAX数据??????
??? org.apache.struts2.dispatcher.StreamResult??????
velocity??????
??? 处理Velocity模板??????
??? org.apache.struts2.dispatcher.VelocityResult??????
xslt??????
??? 处理XML/XLST模板??????
??? org.apache.struts2.views.xslt.XSLTResult??????
plainText??????
??? 显示原始文件内容，例如文件源代码??????
??? org.apache.struts2.dispatcher.PlainTextResult??????
plaintext??????
??? 显示原始文件内容，例如文件源代码??????
??? org.apache.struts2.dispatcher.PlainTextResult
redirect????
??? 重定向到一个URL ，被跳转的页面中丢失传递的信息，如request?????
??? org.apache.struts2.dispatcher.ServletRedirectResult??????
redirectAction??????
??? 重定向到一个Action ，跳转的页面中丢失传递的信息，如request????????
??? org.apache.struts2.dispatcher.ServletActionRedirectResult??????
redirect-action??????
??? 重定向到一个Action ，跳转的页面中丢失传递的信息，如request????????
??? org.apache.struts2.dispatcher.ServletActionRedirectResult??
