JSP自定义标签——调用数据库（通过id号搜索相关信息）

一、创建新表(假设在master数据库下新建)

二、连接数据库

开始-->控制面板-->管理工具-->数据源-->系统DSN-->添加-->SQL Server-->名称：userdb-->服务器：(local)\SQLEXPRESS或选择本机名-->下一步-->下一步-->打钩-更改默认的数据库为:master-->下一步-->完成

三、DefinedTagData项目

1、新建Java类：User

package sample.model;

public class User {

    private int id;

    private String name;

    private String phone;

    public void setId(int id){this.id=id;}//setId中的d必须小写

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

    public void setPhone(String phone){this.phone=phone;}

    public int getID(){return id;}

    public String getName(){return name;}

    public String getPhone(){return phone;}

}

2、新建Java类：UserDAO

package sample.model;



import java.sql.*;

public class UserDAO {

    private ResultSet rst;

    private Connection conn;

    private void open()throws Exception{

        String driver="sun.jdbc.odbc.JdbcOdbcDriver";

        String url= "jdbc:odbc:userdb";//test--定义的数据库的名称

        Class.forName(driver);

        conn=DriverManager.getConnection(url);

    }

    private void close()throws SQLException{

        if(rst!=null) rst.close();

        if(conn!=null) conn.close();

    }

    public void save(User user)throws Exception{

        String sql="";

        open();

        Statement stmt=conn.createStatement();

        rst=stmt.executeQuery(sql);

        close();

    }

    public void load(User user)throws Exception{

        String sql="use master    select name,phone from dbo.usera"+" where id = "+user.getID();

        open();

        Statement stmt=conn.createStatement();

        rst=stmt.executeQuery(sql);

        if(rst.next()){

            user.setName(rst.getString(1));

            user.setPhone(rst.getString(2));

        }

        close();

    }

}

3、创建TLD文件
　　新建文件--> Web--> 标记库描述符

　　TLD名称：Data　　前缀：data

4、创建标记处理程序

　　新建文件--> Web-->标记处理程序

　　类名：DataTag　　包：sample.tag　　要扩展的标记支持类：SimpleTagSupport

　　TLD文件：WEB-INF--> tlds--> Data　　新建属性：color和id

package sample.tag;



import javax.servlet.jsp.tagext.*;

import javax.servlet.jsp.JspWriter;

import javax.servlet.jsp.JspException;

import sample.model.*;



public class DataTag extends TagSupport {   

    private String id;//添加的属性

    public void setId(String id) {

        this.id = id;

    }

    private String color;//添加的属性

    public void setColor(String color) {

        this.color = color;

    }

    public int doStartTag(){         

        User user=new User();

        user.setId(Integer.parseInt(id));

        UserDAO dao=new UserDAO();

        try{    

             dao.load(user); 

             JspWriter out=pageContext.getOut(); 

             String html="<br><b style=\"color:"+color+"\">Welcome to Employee Detail Table.</b><br>";

             html+=" <table border=\"1\"><tr><th>员工ID</th><th>员工姓名</th><th>联系电话</th></tr>";

             html+="<tr><td>"+user.getID()+"</td><td>"+user.getName()+"</td><td>"+user.getPhone()+"</td></tr></table>";

             out.println(html);

        }catch(Exception e){

             System.out.println(e.getMessage());

        }

        return SKIP_BODY;      

    }

    

    public int doEndTag() throws JspException{

        return EVAL_PAGE;

    }

}

PS:Data.tld内容

<?xml version="1.0" encoding="UTF-8"?>

<taglib version="2.0" 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 web-jsptaglibrary_2_0.xsd">

  <tlib-version>1.0</tlib-version>

  <short-name>data</short-name>

  <uri>/WEB-INF/tlds/Data</uri>



  <tag>

    <name>DataTag</name>

    <tag-class>sample.tag.DataTag</tag-class>

    <body-content>empty</body-content>

    <attribute>

      <name>id</name>

      <required>true</required>

      <rtexprvalue>true</rtexprvalue>

      <type>java.lang.String</type>

    </attribute>

    <attribute>

      <name>color</name>

      <required>true</required>

      <rtexprvalue>true</rtexprvalue>

      <type>java.lang.String</type>

    </attribute>

  </tag>

  <tag>

    <name>DataTable</name>

    <tag-class>sample.tag.DataTable</tag-class>

    <body-content>JSP</body-content>

    <attribute>

      <name>id</name>

      <required>true</required>

      <rtexprvalue>true</rtexprvalue>

      <type>int</type>

    </attribute>

    <attribute>

      <name>color</name>

      <required>true</required>

      <rtexprvalue>true</rtexprvalue>

      <type>java.lang.String</type>

    </attribute>

  </tag>

</taglib>

View Code

5、index.jsp

<%@page contentType="text/html" pageEncoding="UTF-8"%>



<%@ taglib uri="/WEB-INF/tlds/Data" prefix="data"%>

<html>

    <head>

        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

        <title>JSP Page</title>

    </head>

    <body>        

        <data:DataTag  id="1" color="blue"/>

    </body>

</html>

6、显示结果