Java Servlets：不同类型的属性[重复]

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How do servlets work? Instantiation, sessions, shared variables and multithreading 7 answers

servlet如何工作?实例化,会话,共享变量和多线程7个答案

Was going through some Java Servlets code.

正在浏览一些Java Servlets代码。

I found attributes set and retrieved in 3 different ways.

我找到了以3种不同方式设置和检索的属性。

req.getSession().setAttribute("var1","value1"); 
req.setAttribute("var2", "value2"); 
getServletContext().setAttribute("var3", "value3");

req is a variable of type HttpServletRequest I am a little confused as to what is the difference between the three?

req是HttpServletRequest类型的变量我有点困惑,三者之间有什么区别?

2 个解决方案

#1

req.getSession().setAttribute("var1","value1"); - Is a Session Attribute.

。req.getSession()的setAttribute( “VAR1”, “值1”); - 是会话属性。

req.setAttribute("var2", "value2"); - Is a Request Attribute.

req.setAttribute(“var2”,“value2”); - 是请求属性。

getServletContext().setAttribute("var3", "value3"); - Is a Servlet Context Level (an Application) Attribute.

getServletContext()。setAttribute(“var3”,“value3”); - 是Servlet上下文级别(应用程序)属性。

#2

The first one is a session attribute, the second one is a request attribute and the third one is an attribute belonging to the ServletContext.

第一个是会话属性,第二个是请求属性,第三个是属于ServletContext的属性。

If you don't know what the session is and how it differs from the request, you should be studying how HTTP works.

如果您不知道会话是什么以及它与请求的不同之处,您应该研究HTTP的工作原理。

The ServletContext is a separate place for the server to keep certain information. You'd more often be getting the attributes from there, rather than setting them.

ServletContext是服务器保存某些信息的独立位置。您经常从那里获取属性,而不是设置它们。

#1