JSP - “”VS“”之间的区别是什么

While working with JSP files and servlets , I came across <% … %> and <%= … %> .

在使用JSP文件和servlet时，我遇到了<％...％>和<％= ...％>。

What's the difference between both cases ?

这两种情况有什么区别？

Thanks

谢谢

3 个解决方案

#1

<%= … %> will echo out a variable, where as <% … %> denotes a script or some code that is executed.

<％= ...％>将回显变量，其中<％...％>表示脚本或某些已执行的代码。

Here are the links to the jsp documentation:

以下是jsp文档的链接：

Expression (<%= … %>) : http://java.sun.com/products/jsp/tags/11/syntaxref11.fm4.html
表达式（<％= ...％>）：http：//java.sun.com/products/jsp/tags/11/syntaxref11.fm4.html
Scriptlet (<% … %>) : http://java.sun.com/products/jsp/tags/11/syntaxref11.fm5.html
Scriptlet（<％...％>）：http：//java.sun.com/products/jsp/tags/11/syntaxref11.fm5.html

#2

<%= new java.util.Date() %>

is same as

和...一样

<% out.println(new java.util.Date()) %>

There are three types of Scriptlets :

Scriptlet有三种类型：

Scriptlet Expressions of the form <%= expression %> that are evaluated and inserted into the output
Scriptlet表达式<％= expression％>的表达式，它们被计算并插入到输出中
Scriptlet of the form <% code %> that are inserted into the servlet's service method
插入到servlet的服务方法中的<％code％>形式的Scriptlet
Scriptlet Declarations of the form <%! code %> that are inserted into the body of the servlet class, outside of any existing methods. For ex:

Scriptlet声明形式<％！代码％>，在任何现有方法之外插入到servlet类的主体中。例如：
```
<%!

public int sum(int a, int b) {

return a + b;
}

%>
```

#3

In case of <% ... %> you are adding a server side code. And in case of <%= ... %> you are adding a server side code that automatically prints something. It could be seen as a shortcut for <% out.print( something ) %>.

如果是<％...％>，则表示您正在添加服务器端代码。并且在<％= ...％>的情况下，您正在添加自动打印内容的服务器端代码。它可以被视为<％out.print（something）％>的快捷方式。

#1