JSP自定义标签使用详解

简单写一个可以从数据库中读取配置的单选按钮组件

1. Java部分

package com.pibgstar.demo.tags;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.SimpleTagSupport;
import java.io.IOException;
import java.util.ArrayList;

/**
 * @author pibigstar
 * @create 2018-12-02 17:16
 * @desc 自定义radio组件
 **/
public class RadioTagSupport extends SimpleTagSupport{

    private String code;
    private String tip;
    private String key;
    private String value;
    private ArrayList<RadioVo> list;

    @Override
    public void doTag() throws JspException, IOException {
        getData();
        StringBuilder sp = new StringBuilder();
        sp.append("<div class='radio'>");
        sp.append("<span class='tip'>");
        sp.append(this.getTip());
        sp.append("</span>");
        for (RadioVo r: list) {
            sp.append("<input type='radio' ");
            sp.append("name='");
            sp.append(r.getName());
            sp.append("' value='");
            sp.append(r.getValue());
            if (r.getChecked()) {
                sp.append("' checked />");
            }else {
                sp.append("' />");
            }

            sp.append(r.getShowValue());
        }
        sp.append("</div>");

        JspWriter out = getJspContext().getOut();
        out.write(sp.toString());
        // 从body中获取值
        //StringWriter sw = new StringWriter();
        //getJspBody().invoke(sw);
        //getJspContext().getOut().write(sw.toString());

    }

    private void getData() {
        list = new ArrayList();
        // 这里可以通过code值，拿到数据库中自己配置的值，这里只是简单的封装几个固定的值
        RadioVo r1 = new RadioVo();
        r1.setName("sex");
        r1.setValue("1");
        r1.setShowValue("男");
        RadioVo r2= new RadioVo();
        r2.setName("sex");
        r2.setValue("2");
        r2.setShowValue("女");
    }

    public String getCode() {
        return code;
    }

    public void setCode(String code) {
        this.code = code;
    }

    public String getTip() {
        return tip;
    }

    public void setTip(String tip) {
        this.tip = tip;
    }

    public String getKey() {
        return key;
    }

    public void setKey(String key) {
        this.key = key;
    }

    public String getValue() {
        return value;
    }

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

    public ArrayList<RadioVo> getList() {
        return list;
    }

    public void setList(ArrayList<RadioVo> list) {
        this.list = list;
    }
}


class RadioVo {
    private String name;
    private String value;
    private String showValue;
    private Boolean checked;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getValue() {
        return value;
    }

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

    public String getShowValue() {
        return showValue;
    }

    public void setShowValue(String showValue) {
        this.showValue = showValue;
    }

    public Boolean getChecked() {
        return checked;
    }

    public void setChecked(Boolean checked) {
        this.checked = checked;
    }
}

2. tld编写

<?xml version="1.0" encoding="UTF-8" ?>
<taglib xmlns="http://java.sun.com/xml/ns/javaee"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd"
        version="2.1">
    <description>JSP 自定义标签</description>
    <display-name>pibigstar core</display-name>
    <tlib-version>1.0</tlib-version>
    <short-name>pi</short-name>

    <tag>
        <description>myself radio</description>
        <name>radio</name>
        <tag-class>com.pibgstar.demo.tags.RadioTagSupport</tag-class>
        <body-content>JSP</body-content>
        <attribute>
            <name>code</name>
            <required>true</required>
            <rtexprvalue>false</rtexprvalue>
        </attribute>
        <attribute>
            <name>tip</name>
            <required>false</required>
            <rtexprvalue>false</rtexprvalue>
        </attribute>
    </tag>

</taglib>

3. JSP中使用

<%@taglib prefix="pi" uri="WEB-INFO/tlds/pibigstar-pi.tld" %>

<html>
<head>
    <title>自定义radio标签使用</title>
</head>
<body>
<pi:radio code="SEX" tip="性别"></pi:radio>
</body>
</html>