what is jsp expression

The JSP expression becomes the outprint() method after the page is converted into a Servlet. Therefore, the JSP expression has the same function as the out.print() method embedded in the scriptlet in the JSP page. If an object is output through a JSP expression, the object's toString() method will be automatically called, and the expression will output the content returned by the toString() method.

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Expression is used to output information on the page. Its usage format is as follows:

<%=变量或可以返回值的方法或 Java 表达式%>

Pay special attention to the "< There should be no space between %" and ".

JSP expressions can be applied to the following situations.

Output content to the page:

<% String name = "www.123.com"; %>
用户名：<%=name%></p>
<p>The above code will generate the following running results: </p>
<pre class="brush:php;toolbar:false">用户名：www.123.com

Generate a dynamic link address ：

<% String path = "welcome.jsp"; %>
<a href="<%=path%>">链接到welcome.jsp</a>

The above code will generate the following HTML code:

<a href="welcome.jsp">链接到 welcome.jsp</a>

Dynamicly specify the Form form processing page

<% String name = "logon.jsp"; %>
<form action="<%=name%>"></form>

The above code will generate The following HTML code:

<form action="logon.jsp"></form>

Name the elements generated by the loop statement

<%for(int i=1;i<3;i++) 
{
%>
file<%=i%>:
<input type="text" name="<%="file"+i%>"><br>
<%}%>

The above code will generate the following HTML code:

file1:<input type="text" name="file1"><br>
file2:<input type="text" name="file2"><br>

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