<hw:helloworld>
ここがボディの記述
</hw:helloword>

<hw:helloworld/>

package javahello;

import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;

public class HelloWorldTag extends TagSupport {
  public int doStartTag() throws JspException {
    try {
      // Hello Worldと出力
      pageContext.getOut().print("Hello World");
    } catch (Exception e) {
      throw new JspException(e.getMessage());
    }
    return SKIP_BODY;
  }

  public int doEndTag() {
    return EVAL_PAGE;
  }
}

C:\作業フォルダ\JavaHello>

<taglib>
  <tlibversion>1.0</tlibversion>
  <jspversion>1.1</jspversion>
  <shortname>javahello</shortname>
  <info>JavaでHello World タグライブラリ</info>

  <tag>
    <name>helloworld</name>
    <tagclass>javahello.HelloWorldTag</tagclass>
    <bodycontent>empty</bodycontent>
    <info>Hello Worldと出力</info>
  </tag>

</taglib>

package javahello;

import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
import java.sql.*;

public class HelloWorldQueryTag extends BodyTagSupport {
  String url;
  String jdbcClass;
  String userName;
  String passwd;

  Connection con;
  Statement stmt;


  public void setUrl(String url) {
    this.url = url;
  }
  public String getUrl() {
    return url;
  }
  public void setJdbcClass(String jdbcClass) {
    this.jdbcClass = jdbcClass;
  }
  public String getJdbcClass() {
    return jdbcClass;
  }
  public void setUserName(String userName) {
    this.userName = userName;
  }
  public String getUserName() {
    return userName;
  }
  public void setPasswd(String passwd) {
    this.passwd = passwd;
  }
  public String getPasswd() {
    return passwd;
  }

  public int doAfterBody() throws JspTagException {
    BodyContent bc = getBodyContent();
    String query = bc.getString();
    bc.clearBody();
    try {
      // ドライバクラスをロード
      Class.forName(jdbcClass);
      // データベースへ接続
      con = DriverManager.getConnection(url, userName, passwd);
      // ステートメントオブジェクトを生成
      stmt = con.createStatement();
      // 結果セットを取得
      ResultSet result = stmt.executeQuery(query);
      // 属性をセット
      pageContext.setAttribute(id,result);
    } catch (Exception e) {
      throw new JspTagException(e.getMessage());
    }
    return SKIP_BODY;
  }
  public void release() {
    try {
      stmt.close();
      con.close();
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}

package javahello;

import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
import java.sql.*;
import java.io.*;

public class HelloWorldBodyTag extends BodyTagSupport {
  private ResultSet result;

  public HelloWorldBodyTag() {
    super();
  }
  public ResultSet getResult() {
    return result;
  }
  public void setResult(ResultSet result) {
    this.result = result;
  }

  public int doStartTag() throws JspTagException {
    result = (ResultSet) pageContext.getAttribute(id);
    try {
      if (result.next()) {
        pageContext.setAttribute(id, result);
        // 結果が存在する場合はボディを評価する
        return EVAL_BODY_AGAIN;
      } else {
        return SKIP_BODY;
      }
    } catch (Exception e) {
      throw new JspTagException(e.getMessage());
    }
  }

  public int doAfterBody() throws JspTagException {
    // ボディの内容を取得
    BodyContent body = getBodyContent();
    try {
      // ボディを出力
      body.writeOut(getPreviousOut());
    } catch (IOException e) {
      throw new JspTagException(e.getMessage());
    }
    body.clearBody();
    try {
      if (result.next()) {
        // まだ行が残っている場合はボディの評価を繰り返す
        return EVAL_BODY_AGAIN;
      } else {
        return SKIP_BODY;
      }
    } catch (SQLException e) {
      throw new JspTagException(e.getMessage());
    }
  }

  public int doEndTag() {
    return EVAL_PAGE;
  }

  public void release() {
    result = null;
  }
}

package javahello;
import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
import java.io.IOException;

public class HelloWorldBodyTEI extends TagExtraInfo {
  public VariableInfo[] getVariableInfo(TagData tagData) {
    VariableInfo[] vars = new VariableInfo[1];
    vars[0] = new VariableInfo(tagData.getId(), 
                               "java.sql.ResultSet", 
                               true,
                               VariableInfo.NESTED);
    return vars;
  }
}

<?xml version="1.0" encoding="Shift_JIS" ?>
<!DOCTYPE taglib PUBLIC 
   "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.1//EN" 
   "http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd">
<taglib>
  <tlibversion>1.0</tlibversion>
  <jspversion>1.1</jspversion>
  <shortname>javahello</shortname>
  <info>JavaでHello World タグライブラリ</info>

  <tag>
    <name>helloworld</name>
    <tagclass>javahello.HelloWorldTag</tagclass>
    <bodycontent>empty</bodycontent>
    <info>Hello Worldと出力</info>
  </tag>

  <tag>
    <name>query</name>
    <tagclass>javahello.HelloWorldQueryTag</tagclass>
    <bodycontent>tagdependent</bodycontent>
    <info>結果セットを取得</info>

    <attribute>
      <name>url</name>
      <required>true</required>
    </attribute>
    <attribute>
      <name>jdbcClass</name>
      <required>true</required>
    </attribute>
    <attribute>
      <name>userName</name>
      <required>true</required>
    </attribute>
    <attribute>
      <name>passwd</name>
      <required>true</required>
    </attribute>
    <attribute>
      <name>id</name>
      <required>true</required>
    </attribute>
  </tag>

  <tag>
    <name>foreach</name>
    <tagclass>javahello.HelloWorldBodyTag</tagclass>
    <teiclass>javahello.HelloWorldBodyTEI</teiclass>
    <bodycontent>JSP</bodycontent>
    <info>結果セットを表示</info>

    <attribute>
      <name>id</name>
      <required>true</required>
    </attribute>
  </tag>
</taglib>

<%@ page contentType="text/html; charset=Shift_JIS" %>
<%@ page import="javahello.*" %>
<%@ taglib uri="/jsp/helloworld.tld" prefix="hw" %>
<html>
<head>
<title>Hello World Jsp Custom Tag</title>
</head>
<body>
<hw:query jdbcClass="org.gjt.mm.mysql.Driver"
        url="jdbc:mysql:///hellodb?useUnicode=true&characterEncoding=SJIS"
        userName=""
        passwd=""
        id="helloResult">
SELECT * FROM HELLO_WORLD_TABLE
</hw:query>

<table border="1">
<tr>
<th>NO</th>
<th>言語</th>
<th>メッセージ</th>
</tr>
<hw:foreach id="helloResult">
<tr>
<td><%=helloResult.getInt("NO") %></td>
<td><%=helloResult.getString("LANGUAGE") %></td>
<td><%=helloResult.getString("MESSAGE") %></td>
</tr>
</hw:foreach>
</table>
</body>
</html>