HttpServletRequest的属性字段如何映射到原始HTTP请求？ [英] How the attribute field of a HttpServletRequest maps to a raw HTTP request?

问题描述

在Java中，可以使用getAttribute方法检索HttpServletRequest对象的属性字段：

In Java, the attribute field of a HttpServletRequest object can be retrieved using the getAttribute method:

String myAttribute = request.getAttribute("[parameter name]");

HttpServletRequest属性数据存储在原始HTTP请求中的位置？它是否在请求的主体中？

Where the HttpServletRequest attribute data is stored in a raw HTTP request? Is it in the body of the request?

例如，我正在尝试创建一个原始的GET HTTP请求，该请求将使用某个客户端程序发送到我的servlet。我的servlet.doGet（）方法是这样的：

For example, I'm trying to create a raw GET HTTP request that will be sent to my servlet using some client program. My servlet.doGet() method would be something like this:

public void doGet(HttpServletRequest request, HttpServletResponse response)
{
     String myAttribute = request.getAttribute("my.username");
     ...
}

我应该在哪里放'my.username '原始HTTP请求中的数据，以便'myAttribute'字符串在归属后收到值John Doe？

Where should I put the 'my.username' data in the raw HTTP request so that the 'myAttribute' String receives the value "John Doe" after the attribution?

推荐答案

要添加到@ gid的答案，HTTP请求中的属性不会以任何方式存在，因为它在线路上传播。它们是在处理请求时（由您的代码创建的）。一个非常常见的用途是使服务器集（也就是创建）一些属性，然后转发到将使用这些属性的JSP。也就是说，HTTP请求到达并发送到Servlet。 Servlet附加了一些属性。完成额外的服务器端处理，最终将页面发送到使用属性的JSP。响应在JSP中生成。 HTTP请求和HTTP响应不包含任何属性。属性是100％纯粹的服务器端信息。

To add to @gid's answer, attributes are not present in any way in the HTTP request as it travels over the wire. They are created (by your code) when processing the request. A very common use is to have a server set (aka create) some attributes and then forward to a JSP that will make use of those attributes. That is, an HTTP request arrives and is sent to a Servlet. The Servlet attaches some attributes. Additional server-side processing is done, eventually sending the page to a JSP, where the attributes are used. The response is generated in the JSP. The HTTP request and the HTTP response do not contain any attributes. Attributes are 100% purely server-side information.

当单个给定的HTTP请求完成后，这些属性可用于垃圾收集（除非它们保留在其他位置，例如会话）。属性仅与单个请求对象相关联。

When a single given HTTP request has completed, the attributes become available for garbage collection (unless they are persisted in some other location, such as a session). Attributes are only associated with a single request object.

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