An introduction to the role and use of the <base> tag in HTML-HTML Tutorial-php.cn

An introduction to the role and use of the tag in HTML

黄舟

Release： 2017-06-19 17:57:25

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Normally, the browser will extract the corresponding elements from the URL of the current document to fill in the blanks in the relative URL
This sentence, I also don’t understand

how to formulate a url address. For example, if you use base to formulate it, you can call
pictures, music, etc. under a certain folder. You don’t need to fill in the complete folder. For the address, just write the picture name and song title, and it will automatically find it from the folder you specified above. The

tag specifies the default address or default target for all links on the page.

Normally, the browser will extract the corresponding elements from the URL of the current document to fill in the gaps in the relative URL.
Use the tag to change this. The browser will then no longer use the URL of the current document, but will use the specified base URL to resolve all relative URLs. This includes URLs in , , , <
for m> tags.

Test:

1: The link path placed in front of the base tag can use a relative path and is relative to the current path,

but the link placed after it will use a relative path. The path specified relative to base.
2: After using the base tag, the relative path of the link in the body will be relative to the path specified by base.
3: After using the base default target, the subsequent opening method will be opened in the method specified by base, unless the opening method is defined later.
Summary: base actually defines a default address and default target. All link elements after it will work.

The base tag is a base link tag and a single tag. Used to change the parameter default value for all link tags in the document. It can only be applied between the tags <

head > and . All relative paths on your web pages will be preceded by the address pointed to by the base link when linking.
The base element can specify the base URL of all links in the page

We can use the href
attribute in the tag to set all "relative base URLs".

This is the code on the JSP side

Uses the tag in the html file:

<%
String path = request.getContextPath();
// 获得项目完全路径（假设你的项目叫myWork，那么获得到的地址就是 http://localhost:8080/myWork/）:
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
// 将 "项目路径basePath" 放入pageContext中
%>
<html>
<head>
<base href=" <%=basePath%>">
//base只能应用于标记<head>与</head>之间
</head>
// 这里我们就可以直接使用相对路径(即: 相对于base标签)
<a href="jsp/login.jsp">Login </a>
</html>
当我们去执行上面的那段JSP代码后，我们可以在浏览器中可以查看，他所返回给客户端的html代码:
执行完上述JSP后，所返回的html代码如下:
<html>
<head>
<base href="http://localhost:8080/myWork/">
</head>
// 设置了 <base>后，相对路径，相对于的就是base中的路径，而不再是浏览器地址的请求路径啦~~~
<a href="jsp/login.jsp">Login </a>
</html>

Copy after login

We can see that the html code returned by JSP contains Content.

In other words, in this html file, all "relative links (for example: )" encountered are paths relative to base
(ie: http://localhost:8080/myWork/)

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