JSTL自定义标签

HelloSimpleTag.java

package cn.stud.wlc.tag;

import java.io.IOException;

import javax.servlet.jsp.JspContext;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.JspFragment;
import javax.servlet.jsp.tagext.JspTag;
import javax.servlet.jsp.tagext.SimpleTag;

public class HelloSimpleTag implements SimpleTag {

//设置属性
private String value;
private String count;
private PageContext pagecontext;

//set方法是必须的 这些属性在tld文件里描述

public void setValue(String value) {
        this.value = value;
    }

    public void setCount(String count) {
        this.count = count;
    }

    public void doTag() throws JspException, IOException {
        // TODO Auto-generated method stub  
        //执行 标签体逻辑 实际应该编写到该方法中
        //可以后去PageContext的八个成员变量
        System.out.println("value:"+value+"count:"+count);
        pagecontext.getOut().print("hello word");

    }

    public JspTag getParent() {
        System.out.println("getParent");
        return null;
    }

    public void setJspBody(JspFragment arg0) {
        // TODO Auto-generated method stub
        System.out.println("setJspBody");
    }

    public void setJspContext(JspContext arg0) {
        // TODO Auto-generated method stub 
        //jsp页面的PageContext对象传进来
        //jsp引擎调用
        this.pagecontext = (PageContext) arg0;
        System.out.println("setJspContext");
    }

    public void setParent(JspTag arg0) {
        // TODO Auto-generated method stub
        System.out.println("setParent");
    }

}


（2）继承simpleTagSupport

package cn.stud.wlc.tag;

import java.io.IOException;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.SimpleTagSupport;

public class MaxTag extends SimpleTagSupport {
private String num1;
private String num2;

public void setNum1(String num1) {
this.num1 = num1;
}

public void setNum2(String num2) {
this.num2 = num2;
}

//dotag之后的方法就不用挨个写了

public void doTag() throws JspException, IOException {
int a=0;
int b=0;

PageContext pageContext = (PageContext) getJspContext();
JspWriter out =pageContext.getOut();
try {
a=Integer.parseInt(num1);
b=Integer.parseInt(num2);
out.print(a>b?a:b);

} catch (Exception e) {
out.print("输入格式不正确");
}
}

}