jsp 自定义标签的写法

1.定义标签类。

标签扩展 BodyTagSupport 类。

package testtag;

import java.io.IOException;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspTagException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.BodyTagSupport;
import javax.servlet.jsp.tagext.TagSupport;

public class LinkTag extends BodyTagSupport {

    public LinkTag() {
        // TODO Auto-generated constructor stub
    }
    
    private String href="";
    
    public String getHref() {
        return href;
    }

    public void setHref(String href) {
        this.href = href;
    }

    public int doStartTag() throws JspTagException {    
        return EVAL_BODY_BUFFERED;
      }
      
      public int doEndTag() throws JspTagException {
          
        String body = this.getBodyContent().getString();
        HttpServletRequest request = (HttpServletRequest)pageContext.getRequest();
        
        try {
            JspWriter writer= pageContext.getOut();
            String str="<a href='"+this.href+"'>"+body+"</a>";
            pageContext.getOut().print(str);
        }
        catch (IOException e) {
          throw new JspTagException(e.getMessage());
        }
        return SKIP_BODY;
      }
}

2.定义标签文件 MyTagLib.tld。

<?xml version="1.0" encoding="ISO-8859-1"?>
<taglib>
<tlib-version>1.0</tlib-version>
<jsp-version>1.2</jsp-version>
<tag>
  <name>linktag</name>
  <tag-class>testtag.LinkTag</tag-class>
  <body-content>jsp</body-content>
  <attribute>
    <name>href</name>
    <required>true</required>
    <rtexprvalue>true</rtexprvalue>
  </attribute>
</tag>

</taglib>

3.在web.xml中添加引用。

<jsp-config>
        <taglib>
            <taglib-uri>MyTagLib</taglib-uri>
            <taglib-location>/WEB-INF/MyTagLib.tld</taglib-location>
        </taglib>
    </jsp-config>

4.在页面中调用自定义标签。

<%@taglib uri="MyTagLib" prefix="mytag"%>
<mytag:linktag href="http://www.baidu.com">测试标签</mytag:linktag>