转自huangqiqing123.iteye.com/blog/1922014
1 <body> 2 <%! 3 4 //1、可定义方法 5 public String outMethod(){ 6 return "outMethod"; 7 } 8 //2、可定义static方法 9 public static String outStaticMethod(){ 10 return "outStaticMethod"; 11 } 12 //3、可定义static属性 13 public static int count = 0; 14 15 //4、不可以使用out对象 16 %> 17 18 <% 19 //1、不可定义方法 20 //2、不可定义static方法 21 //3、不可定义static属性 22 23 //可以使用out对象 24 out.print(outMethod()); 25 out.print("<br>"); 26 out.print(outStaticMethod()); 27 out.print("<br>"); 28 out.print(count); 29 %> 30 </body>
1 <body> 2 <%! 3 4 //1、可定义方法 5 public String outMethod(){ 6 return "outMethod"; 7 } 8 //2、可定义static方法 9 public static String outStaticMethod(){ 10 return "outStaticMethod"; 11 } 12 //3、可定义static属性 13 public static int count = 0; 14 15 //4、不可以使用out对象 16 %> 17 18 <% 19 //1、不可定义方法 20 //2、不可定义static方法 21 //3、不可定义static属性 22 23 //可以使用out对象 24 out.print(outMethod()); 25 out.print("<br>"); 26 out.print(outStaticMethod()); 27 out.print("<br>"); 28 out.print(count); 29 %> 30 </body>
经Tomcat编译后，生成的java文件如下：
package org.apache.jsp; import javax.servlet.*; import javax.servlet.http.*; import javax.servlet.jsp.*; public final class test_jsp extends org.apache.jasper.runtime.HttpJspBase implements org.apache.jasper.runtime.JspSourceDependent { //1、可定义方法 public String outMethod(){ return "outMethod"; } //2、可定义static方法 public static String outStaticMethod(){ return "outStaticMethod"; } //3、可定义static属性 public static int count = 0; //4、不可以使用out对象 private static final JspFactory _jspxFactory = JspFactory.getDefaultFactory(); private static java.util.List _jspx_dependants; private javax.el.ExpressionFactory _el_expressionfactory; private org.apache.AnnotationProcessor _jsp_annotationprocessor; public Object getDependants() { return _jspx_dependants; } public void _jspInit() { _el_expressionfactory = _jspxFactory.getJspApplicationContext(getServletConfig().getServletContext()).getExpressionFactory(); _jsp_annotationprocessor = (org.apache.AnnotationProcessor) getServletConfig().getServletContext().getAttribute(org.apache.AnnotationProcessor.class.getName()); } public void _jspDestroy() { } public void _jspService(HttpServletRequest request, HttpServletResponse response) throws java.io.IOException, ServletException { PageContext pageContext = null; HttpSession session = null; ServletContext application = null; ServletConfig config = null; JspWriter out = null; Object page = this; JspWriter _jspx_out = null; PageContext _jspx_page_context = null; try { response.setContentType("text/html; charset=utf-8"); pageContext = _jspxFactory.getPageContext(this, request, response, null, true, 8192, true); _jspx_page_context = pageContext; application = pageContext.getServletContext(); config = pageContext.getServletConfig(); session = pageContext.getSession(); out = pageContext.getOut(); _jspx_out = out; out.write(" "); out.write("<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> "); out.write("<html> "); out.write("<head> "); out.write("<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> "); out.write("<title>Insert title here</title> "); out.write("</head> "); out.write("<body> "); out.write(" "); out.write(" "); //1、不可定义方法 //2、不可定义static方法 //3、不可定义static属性 //可以使用out对象 out.print(outMethod()); out.print("<br>"); out.print(outStaticMethod()); out.print("<br>"); out.print(count); out.write(" "); out.write("</body> "); out.write("</html>"); } catch (Throwable t) { if (!(t instanceof SkipPageException)){ out = _jspx_out; if (out != null && out.getBufferSize() != 0) try { out.clearBuffer(); } catch (java.io.IOException e) {} if (_jspx_page_context != null) _jspx_page_context.handlePageException(t); } } finally { _jspxFactory.releasePageContext(_jspx_page_context); } } }
在生成的java文件中，我们可以看到，<%! %>中的代码对应于java类文件的成员方法、静态方法，静态变量，而<% %>中的代码对应于java类文件的_jspService方法中的代码（_jspService对应于servlet中的service方法）， 这也就是为什么在<% %>中不能声明方法、静态变量的原因了（方法中是不可以再创建方法的）。