<jsp:include page=""/> action和<c:import url=""/> jstl tag都是动态加载。但是c:import则更为灵活。jsp:include只能include当前web app下的页面,而c:import则可以从外部容器加载内容。
动态加载和静态加载最根本的不同在于,jsp生成的servlet的不同。在tomcat下静态(include directive)和动态(include action)的_jspService()代码如下:
- out.write(“<html><body> ”);
- <span style="font-family: webdings;">out.write(“ <html> <body> <img src=”images/Web-Services.jpg” >
- <br> <em><strong>We know how to make SOAP suck less.</strong></em> <br>
- </body> </html> ”);</span>
- out.write(“ <br> <em>We can help.</em> <br><br> Contact us at: “);
- out.write((java.lang.String) org.apache.jasper.runtime.PageContextImpl.
- proprietaryEvaluate(“${initParam.mainEmail}”, java.lang.String.class,
- (PageContext)_jspx_page_context, null, false));
- out.write(“ </body></html>”);
而动态的则是:
- out.write(“<html><body> ”);
- <span style="font-family: webdings;">org.apache.jasper.runtime.JspRuntimeLibrary.include(request, response,
- “Header.jsp”, out, false);</span>
- out.write(“ <br> <em>We can help.</em> <br><br> Contact us at: “);
- out.write((java.lang.String) org.apache.jasper.runtime.PageContextImpl.
- proprietaryEvaluate(“${initParam.mainEmail}”, java.lang.String.class,
- (PageContext)_jspx_page_context, null, false));
- out.write(“ </body></html>”);
可以看到静态的是将要include的页面直接写在了servlet里面,这样当servlet生成之后,就不能修改了。动态的则不同,运行时才会导入页面。
另外jsp:include和c:import可以分别使用jsp:param和c:param来设置参数来控制要include的页面。