jsp自定标签

package cn.choi.tag;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;

@SuppressWarnings("serial")
public class DBconnectionTag extends TagSupport {
    private String driver;
    private String url;
    private String sql;
    private String username;
    private String password;

    Connection conn = null;
    Statement stmt = null;
    ResultSet rs = null;

    @Override
    public int doEndTag() throws JspException {
        try {
            Class.forName(this.driver);
            conn = DriverManager.getConnection(this.url, this.username,
                    this.password);
            stmt = conn.createStatement();
            rs = stmt.executeQuery(this.sql);
            if (rs != null) {
                while (rs.next()) {

                    pageContext.getOut().print(rs.getString(2) + "<br/>");
                }
            }
            return EVAL_PAGE;

        } catch (Exception e) {
            e.printStackTrace();
            return SKIP_PAGE;
        } finally {

            try {
                if (rs != null) {
                    rs.close();
                }
                if (stmt != null) {
                    stmt.close();
                }
                if (conn != null) {
                    rs.close();
                }
            } catch (Exception e2) {
                e2.printStackTrace();
            }

        }

    }

    public void setUrl(String url) {
        this.url = url;
    }

    public void setSql(String sql) {
        this.sql = sql;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public void setDriver(String driver) {
        this.driver = driver;
    }

}

<?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">
    <!-- 标签库的描述 -->
    <description>A tag library exercising SimpleTag handlers</description>
    <!-- 自定义标签的版本为1.0 (必须元素) -->
    <tlib-version>1.0</tlib-version>
    <!-- 简短的名称(元素) -->
    <short-name>SimpleTag</short-name>
    <!-- 定义此标签的uri路径，用于唯一标示的数据库，便于页面引用 -->
    <uri>/choi-tag</uri>

    <tag>
        <!--该标签名称（必须元素） -->
        <name>loginDate</name>
        <!-- 全限定名(必须元素) -->
        <tag-class>cn.choi.tag.LoginDateTag</tag-class>
        <!-- 指明主题类型 -->
        <body-content>empty</body-content>
    </tag>

    <tag>
        <description>当页面request的show值为show时执行标签体的内容</description>
        <name>SkipBodyOrEvalBodyInclude</name>
        <tag-class>cn.choi.tag.SkipBodyOrEvalBodyIncludeTag</tag-class>
        <!-- 表示标签体可以包含EL表达式和JSP的动作元素，但不能包含脚本表达式 -->
        <body-content>scriptless</body-content>
    </tag>

    <tag>
        <description>当前的请求只能通过连接或form提交进行</description>
        <name>SkipPageOrEvalPage</name>
        <tag-class>cn.choi.tag.StartPagorEvalPagTag</tag-class>
        <!-- 表示标签体可以包含EL表达式和JSP的动作元素，但不能包含脚本表达式 -->
        <body-content>empty</body-content>
    </tag>
    <tag>
        <description>连接数据库</description>
        <name>DBconnnectionTag</name>
        <tag-class>cn.choi.tag.DBconnectionTag</tag-class>
        <body-content>empty</body-content>

        <attribute>
            <name>driver</name>
            <required>true</required>
        </attribute>

        <attribute>
            <name>url</name>
            <required>true</required>
        </attribute>
        <attribute>
            <name>sql</name>
            <required>true</required>
        </attribute>
        <attribute>
            <name>username</name>
            <required>true</required>
        </attribute>
        <attribute>
            <name>password</name>
            <required>true</required>
        </attribute>
    </tag>
</taglib>

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ taglib uri="/choi-tag" prefix="choi"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
</head>

<body>
    <choi:DBconnnectionTag 
    driver="oracle.jdbc.driver.OracleDriver"
    password="admin" 
    username="bysj" 
    sql=" select * from users" 
    url="jdbc:oracle:thin://localhost:1521:orcl"  />
</body>
</html>