JSP 简单标签extends SimpleTagSupport

1.控制JSP页面某一部分内容是否执行

public void doTag()

this.getJspBody().invoke(null);执行

空白，不执行

2.控制JSP页面内容重复执行

 package cn.itcast.web.simpletag;

 import java.io.IOException;

 import javax.servlet.jsp.JspException;

 import javax.servlet.jsp.tagext.JspFragment;

 import javax.servlet.jsp.tagext.SimpleTagSupport;

 public class SimpleTagDemo2 extends SimpleTagSupport {

     @Override

     public void doTag() throws JspException, IOException {

         // TODO Auto-generated method stub

         JspFragment jf = this.getJspBody();

         for (int i = 0; i < 10; i++) {

             jf.invoke(null);

         }

     }

 }

3.修改JSP页面内容输出

 package cn.itcast.web.simpletag;

 import java.io.IOException;

 import java.io.StringWriter;

 import javax.servlet.jsp.JspContext;

 import javax.servlet.jsp.JspException;

 import javax.servlet.jsp.tagext.JspFragment;

 import javax.servlet.jsp.tagext.SimpleTagSupport;

 public class SimpleTagDemo3 extends SimpleTagSupport {

     @Override

     public void doTag() throws JspException, IOException {

         // TODO Auto-generated method stub

         JspFragment jf = this.getJspBody();

         StringWriter sw = new StringWriter();

         jf.invoke(sw);

         String content = sw.getBuffer().toString();

         content = content.toUpperCase();

         JspContext pageContent = this.getJspContext();

         pageContent.getOut().write(content);

     }

 }

4.控制标签余下的JSP不执行

 package cn.itcast.web.simpletag;

 import java.io.IOException;

 import javax.servlet.jsp.JspException;

 import javax.servlet.jsp.SkipPageException;

 import javax.servlet.jsp.tagext.SimpleTagSupport;

 public class SimpleTagDemo4 extends SimpleTagSupport {

     @Override

     public void doTag() throws JspException, IOException {

         // TODO Auto-generated method stub

         throw new SkipPageException();

     }

 }

开发带属性的标签

要想让一个自定义标签具有属性，通常需要完成两个任务：

在标签处理器中编写每个属性对应的setter方法

 package cn.itcast.web.simpletag;

 import java.io.IOException;

 import javax.servlet.jsp.JspException;

 import javax.servlet.jsp.tagext.SimpleTagSupport;

 public class SimpleTagDemo5 extends SimpleTagSupport {

     private int count;

     public void setCount(int count) {

         this.count = count;

     }

     @Override

     public void doTag() throws JspException, IOException {

         // TODO Auto-generated method stub

         for (int i = 0; i < count; i++) {

             this.getJspBody().invoke(null);

         }

     }

 }

在tld文件中描述标签的属性

     <tag>

         <name>demo5</name>

         <tag-class>cn.itcast.web.simpletag.SimpleTagDemo5</tag-class>

         <body-content>scriptless</body-content>

         <attribute>

             <name>count</name>

             <required>true</required>

             <rtexprvalue>true</rtexprvalue>

         </attribute>

     </tag>

巴特西

JSP 简单标签extends SimpleTagSupport

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