1 package cn.itcast.web.tag; 2  3 import java.io.IOException; 4 import java.io.StringWriter; 5  6 import javax.servlet.jsp.JspException; 7 import javax.servlet.jsp.tagext.JspFragment; 8 import javax.servlet.jsp.tagext.SimpleTagSupport; 9 10 //控制标签体内容为大写11 public class SimpleTagDemo1 extends SimpleTagSupport {12     13     14     15     @Override16     public void doTag() throws JspException, IOException {17         JspFragment jf = this.getJspBody();18         StringWriter sw = new StringWriter();19         jf.invoke(sw);20         21         String content = sw.toString();22         content = content.toUpperCase();23         24         this.getJspContext().getOut().write(content);25     }26 27     28 29 }