自定义标签 jsp

使用标签输出客户机IP。


1.编写一个实现tag接口的java类


public class ViewIPTag extends TagSupport {


@Override
public int doStartTag() throws JspException {

HttpServletRequest request = (HttpServletRequest) this.pageContext.getRequest();
JspWriter out = this.pageContext.getOut();


String ip = request.getRemoteAddr();
    try {
out.print(ip);
} catch (IOException e) {
throw new RuntimeException(e);
}

return super.doStartTag();
}
}


2.在tld文件中对标签处理器类进行描述（tld文件的位置:WEB-INF下,可以抄C:\apache-tomcat-6.0.20\webapps\examples\WEB-INF\jsp2\jsp2-example-taglib.tld）
<?xml version="1.0" encoding="UTF-8" ?>


<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
    version="2.0">
    
    <description>A tag library exercising SimpleTag handlers.</description>
    <tlib-version>1.0</tlib-version>
    <short-name>itcast</short-name>
    <uri>http://www.itcast.cn</uri>
    
    
    <tag>
        <name>viewIP</name>
<tag-class>cn.itcast.web.tag.ViewIPTag</tag-class>
<body-content>empty</body-content>
    </tag>
    
</taglib>




3.在jsp页面中导入和使用自定义标签