拜讀了 bibiye 的《一個高效簡潔的 Struts 分頁方法 ( 原創 ) 》后，根據 bibiye 的方法，自己修改了一下，也弄了一個 struts 下的分頁，大家見笑了！

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我的方法是，根據用戶點擊導航條上的頁號 (offset) ，到 DB 中讀取該頁的數據 ( 不是一次全部讀出 ) ，點到哪頁讀哪頁的數據， JBX + tomcat + oracle 下測試通過，數據庫用的表是 oracle 的 emp 表。

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******** 分頁類 Pager.java ，負責生成分頁導航條 ********

?

package page;

?

/**

?* 分頁代碼

?* <p>Title: 分頁 </p>

?* <p>Description: </p>

?* <p>Copyright: Copyright (c) 2005</p>

?* <p>Company: BCS</p>

?* @author Alex

?* @version 1.0

?*/

public class Pager {

? private int offset;

? private int size;

? private int length;

? private String url;

? private String pageHeader;

? public Pager(int offset, int size, int length, String url, String pageHeader) {

??? this.offset = offset;

??? this.size = size;

??? this.length = length;

??? this.url = url;

??? this.pageHeader = pageHeader;

? }

?

? /**

?? * 返回分頁導航條

?? * @param offset int 起始記錄的位置

?? * @param size int 總記錄數

?? * @param length int 步長

?? * @param url String .do 的 url

?? * @param pageHeader String 導航條的前綴文字提示

?? * @return String

?? */

? public String getPageNavigation() {

??? String pageNavigation = ""; // 最終返回的分頁導航條

??? // 記錄數超過一頁 , 需要分頁

??? if (size > length) {

????? String pref; // 前綴

????? if (url.indexOf("?") > -1) {

??????? // 如果 url 中已經包含了其他的參數 , 就把 offset 參數接在后面

??????? pref = "&";

????? }

????? else {

??????? // 如果 url 中沒有別的參數

??????? pref = "?";

????? }

????? // 如果導航條包含 header

????? if (pageHeader != null && pageHeader.length() > 0) {

??????? pageNavigation = pageHeader + " : ";

????? }

????? // 如果不是第一頁 , 導航條將包含“ << ” ( 第一頁 ) 和“ < ” ( 前一頁 )

????? if (offset > 0) {

??????? pageNavigation += "<a href='" + url + pref + "offset=0'>[<<]</a>\n" +

??????????? "<a href='" + url + pref + "offset=" + (offset - length) +

??????????? "'>[<]</a>\n";

????? }

????? // 導航條中 , 排頭的那一頁的 offset 值

????? int startOffset;

????? // 位于導航條中間的那一頁的 offset 值 ( 半徑 )

????? int radius = constants.MAX_PAGE_INDEX / 2 * length;

????? // 如果當前的 offset 值小于半徑

????? if (offset < radius || this.pageCount() <= constants.MAX_PAGE_INDEX) {

??????? // 那么第一頁排頭

??????? startOffset = 0;

????? }

????? else if (offset < size - radius) {

??????? startOffset = offset - radius;

????? }

????? else {

??????? startOffset = (size / length - constants.MAX_PAGE_INDEX) * length;

????? }

????? for (int i = startOffset;

?????????? i < size && i < startOffset + constants.MAX_PAGE_INDEX * length;

?????????? i += length) {

??????? if (i == offset) {

????????? // 當前頁號 , 加粗顯示

????????? pageNavigation += "<b>" + (i / length + 1) + "</b>\n";

??????? }

??????? else {

????????? // 其他頁號 , 包含超鏈接

????????? pageNavigation += "<a href='" + url + pref + "offset=" + i + "'>" +

????????????? (i / length + 1) + "</a>\n";

??????? }

? ????}

????? // 如果不是最后一頁 , 導航條將包含“ > ” ( 下一頁 ) 和“ >> ” ( 最后一頁 )

????? if (offset < size - length) {

??????? pageNavigation += "<a href='" + url + pref + "offset=" +

??????????? (offset + length) + "'>[>]</a>\n" +

??????????? "<a href='" + url + pref + "offset=" + lastPageOffset() +

??????????? "'>[>>]</a>\n";

????? }

//????? System.out.println("radius : " + radius);

//????? System.out.println("start offset : " + startOffset);

????? return pageNavigation;

??? }

??? // 記錄不超過一頁 , 不需要分頁

??? else {

????? return "";

??? }

? }

?

? /**

?? * 返回分頁后的總頁數

?? * @param size int 總記錄數

?? * @param length int 每頁的記錄數

?? * @return int

?? */

? public int pageCount() {

??? int pagecount = 0;

??? if (size % length == 0) {

????? pagecount = size / length;

??? }

??? else {

????? pagecount = size / length + 1;

??? }

??? return pagecount;

? }

?

? /**

?? * 返回最后一頁的記錄數

?? * @param size int 總記錄數

?? * @param length int 每頁的記錄數

?? * @return int

?? */

? public int lastPageSize() {

??? int lastpagesize = 0;

??? if (size % length == 0) {

????? lastpagesize = length;

??? }

??? else {

????? lastpagesize = size % length;

??? }

??? return lastpagesize;

? }

?

? /**

?? * 返回最后一頁的起始記錄位置

?? * @param size int 總記錄數

?? * @param length int 每頁的記錄數

?? * @return int

?? */

? public int lastPageOffset() {

??? return size - lastPageSize();

? }

?

? public int getOffset() {

??? return offset;

? }

?

? public void setOffset(int offset) {

??? this.offset = offset;

? }

?

? public int getSize() {

??? return size;

? }

?

? public void setSize(int size) {

??? this.size = size;

? }

?

? public int getLength() {

??? return length;

? }

?

? public void setLength(int length) {

??? this.length = length;

? }

?

? public String getUrl() {

??? return url;

? }

?

? public void setUrl(String url) {

??? this.url = url;

? }

?

? public String getPageHeader() {

??? return pageHeader;

? }

?

? public void setPageHeader(String pageHeader) {

??? this.pageHeader = pageHeader;

? }

}

?

******** 數據處理類 empDAO.java ，負責訪問 DB ，獲取當前頁面需要顯示的記錄 ********

?

package page;

?

import java.sql.*;

import java.util.*;

?

public class empDAO {

? public empDAO() {

? }

?

? /**

?? * 從 offset 位置起始 , 返回 length 條記錄

?? * @param offset int 起始的記錄位置

?? * @param length int 步長

?? * @param conn Connection 數據庫連接

?? * @return ArrayList

?? */

? public ArrayList findAllEmp(int offset, int length, Connection conn) throws

????? SQLException {

??? PreparedStatement ps = null;

??? ResultSet rs = null;

??? ArrayList emps = new ArrayList();

??? empVO empvo = null;

??? String strSql = "select empno, ename from emp where rowid not in (select rowid from emp where rownum <= ?) and rownum <= ?";

?? ?try {

????? ps = conn.prepareStatement(strSql);

????? ps.setInt(1, offset); // 起始記錄的位置

????? ps.setInt(2, length); // 步長

????? rs = ps.executeQuery();

????? while (rs != null && rs.next()) {

??????? empvo = new empVO();

??????? empvo.setEmpno(rs.getInt("empno"));

??????? empvo.setEname(rs.getString("ename"));

??????? emps.add(empvo);

????? }

??? }

??? catch (SQLException ex) {

????? ex.printStackTrace();

????? throw ex;

??? }

??? return emps;

? }

?

? /**

?? * 返回總的記錄數

?? * @param conn Connection

?? * @throws SQLException

?? * @return int

?? */

? public int getRsTotalCount(Connection conn) throws SQLException {

??? PreparedStatement ps = null;

??? ResultSet rs = null;

??? int rsCount = 0;

??? String strSql = "select count(empno) as empCount from emp";

??? try {

????? ps = conn.prepareStatement(strSql);

????? rs = ps.executeQuery();

????? if (rs != null && rs.next()) {

??????? rsCount = rs.getInt("empCount");

????? }

??? }

??? catch (SQLException ex) {

????? ex.printStackTrace();

????? throw ex;

??? }

??? return rsCount;

? }

}

?

******** 業務類 empBO.java ，調用 empDAO 類 ********

?

package page;

?

import java.util.*;

?

/**

?* BO 類

?* <p>Title: 分頁 </p>

?* <p>Description: </p>

?* <p>Copyright: Copyright (c) 2005</p>

?* <p>Company: BCS</p>

?* @author Alex

?* @version 1.0

?*/

public class empBO {

? private DBPool db = DBPool.newInstance();

? private empDAO empdao = new empDAO();

?

? public empBO() {

? }

?

? /**

?? * 從 offset 位置起始 , 返回 length 條記錄

?? * @param offset int 起始

?? * @param length int 步長

?? * @throws Exception

?? * @return ArrayList

?? */

? public ArrayList findAllEmp(int offset, int length) throws Exception {

??? ArrayList emps = new ArrayList();

??? try {

????? emps = empdao.findAllEmp(offset, length, db.getConnection());

??? }

??? catch (Exception ex) {

????? throw ex;

??? }

??? finally {

????? db.release();

??? }

??? return emps;

? }

?

? /**

?? * 返回總的記錄數

?? * @throws Exception

?? * @return int

?? */

? public int getRsTotalCount() throws Exception {

??? int rsCount = 0;

??? try {

????? rsCount = empdao.getRsTotalCount(db.getConnection());

??? }

??? catch (Exception ex) {

????? throw ex;

??? }

??? finally {

????? db.release();

??? }

??? return rsCount;

? }

}

?

?

********ActionForm 類 empForm.java********

?

package page;

?

import javax.servlet.http.*;

?

import org.apache.struts.action.*;

?

public class empForm

??? extends ActionForm {

? private int offset; // 起始記錄的位置 // 每頁顯示的記錄數

? public ActionErrors validate(ActionMapping actionMapping,

?????????????????????????????? HttpServletRequest httpServletRequest) {

??? /**@todo: finish this method, this is just the skeleton.*/

??? return null;

? }

?

? public void reset(ActionMapping actionMapping,

??????????????????? HttpServletRequest httpServletRequest) {

??? this.offset = 0; // 記錄默認從第一條開始顯示

? }

?

? public int getOffset() {

??? return offset;

? }

?

? public void setOffset(int offset) {

??? this.offset = offset;

? }

?

}

?

?

********Action 類 empAction.java ，控制器，調用 BO 類， Pager 類 ********

?

package page;

?

import java.util.*;

import javax.servlet.http.*;

?

import org.apache.struts.action.*;

?

/**

?* 分頁測試的 Action

?* <p>Title: 分頁 </p>

?* <p>Description: </p>

?* <p>Copyright: Copyright (c) 2005</p>

?* <p>Company: BCS</p>

?* @author Alex

?* @version 1.0

?*/

public class empAction

??? extends Action {

?

? public ActionForward execute(ActionMapping actionMapping,

?????????????????????????????? ActionForm actionForm,

?????????????????????????????? HttpServletRequest httpServletRequest,

?????????????????????????????? HttpServletResponse httpServletResponse) {

??? empForm empform = (empForm) actionForm;

??? return performList(actionMapping, actionForm, httpServletRequest,

?????????????????????? httpServletResponse);

? }

?

? private ActionForward performList(ActionMapping actionMapping,

??????????????????????????????????? ActionForm actionForm,

??????????????????????????????????? HttpServletRequest request,

??????????????????????????????????? HttpServletResponse response) {

??? try {

????? empBO empbo = new empBO();

????? // 獲取外部傳進來的起始記錄號

????? int offset = ( (empForm) actionForm).getOffset();

????? // 獲取每頁的記錄數

????? int pagesize = constants.PAGE_SIZE;

????? // 獲取記錄集合 , 從 offset 開始 , 取 length 條記錄

????? ArrayList emps = empbo.findAllEmp(offset, pagesize);

????? // 計算所有記錄的條數 ( 總記錄數 )

????? int size = empbo.getRsTotalCount();

????? // 外部 url 地址 , 得到形如 : http://localhost:8088/bugMIS/showlist.do 的 String

????? String url = request.getContextPath() + actionMapping.getPath() + ".do";

????? // 實例化分頁類

????? Pager p = new Pager(offset, size, pagesize, url, "Page Navigation");

????? // 獲取分頁導航條

????? //String pageNavigation = p.getPageNavigation();

????? // 將 url 字符串和記錄集合 , 存入 request 中

????? request.setAttribute("pager", p);

????? request.setAttribute("emps", emps);

??? }

??? catch (Exception e) {

????? e.printStackTrace();

????? return actionMapping.findForward("failure");

??? }

??? return actionMapping.findForward("success");

? }

}

?

?

******** 數據庫連接池類 DBPool.java ，可以使用 tomcat 的連接池，也可以不用，這里關閉了 ********

?

package page;

?

import java.sql.*;

import javax.naming.*;

import javax.sql.*;

?

import org.apache.commons.logging.*;

?

/**

?* 系統連接池類

?* <p>Title: Gantoo@91.com</p>

?* <p>Description: </p>

?* <p>Copyright: Copyright (c) 2005</p>

?* <p>Company: BCS</p>

?* @author Alex

?* @version 1.0

?*/

public class DBPool {

? Log log = LogFactory.getLog("DBPool"); // 日志機

? private DBPool() {

? }

?

? private Connection conn = null;

?

? /* true: 使用連接池

???? false: 不使用連接池 , 采用 JDBC 直接連接 */

? private final static boolean USE_DB_POOL = false;

? private final static String jndi_DataSource = "jdbc/BugMIS_ora";

? private final static String jdbcdriver =

????? "oracle.jdbc.driver.OracleDriver";

? private final static String url =

????? "jdbc:oracle:thin:@localhost:1521:myo9";

? private final static String user = "scott";

? private final static String pass = "tiger";

?

? public static DBPool newInstance() {

??? return new DBPool();

? }

?

? /**

?? * 切換是否使用連接池

?? * */

? public Connection getConnection() {

??? if (USE_DB_POOL) {

????? conn = getConnectionByDBPool();

??? }

??? else {

????? conn = getConnectionDirect();

??? }

??? return conn;

? }

?

? /**

?? * 直接采用 JDBC 連接數據庫

?? * */

? private Connection getConnectionDirect() {

??? try {

????? Class.forName(jdbcdriver).newInstance();

????? conn = DriverManager.getConnection(url, user, pass);

??? }

??? catch (SQLException ex) {

????? log.error("Error Connection! " + ex.getMessage());

??? }

??? catch (ClassNotFoundException ex) {

????? log.error("Driver Not Found! " + ex.getMessage());

??? }

??? catch (IllegalAccessException ex) {

????? log.error(ex.getMessage());

??? }

??? catch (InstantiationException ex) {

????? log.error(ex.getMessage());

??? }

??? return conn;

? }

?

? /**

?? * 采用連接池

?? * */

? private Connection getConnectionByDBPool() {

??? try {

????? Context initCtx = new InitialContext();

????? Context ctx = (Context) initCtx.lookup("java:/comp/env");

????? DataSource ds = (DataSource) ctx.lookup(jndi_DataSource);

????? conn = ds.getConnection();

??? }

??? catch (NamingException ex) {

????? log.error("Data Source Not Found! " + ex.getMessage());

????? //System.out.println(" 未找到數據源 " + ex.getMessage());

??? }

??? catch (SQLException ex1) {

????? log.error("Error Connection! " + ex1.getMessage());

????? //System.out.println(" 錯誤的數據連接 " + ex1.getMessage());

??? }

??? return conn;

? }

?

? /**

?? * 釋放連接

?? * */

? public void release() {

??? try {

????? if (!conn.isClosed()) {

??????? conn.close();

????? }

??? }

??? catch (SQLException ex) {

????? log.error("Connection Closing Error! " + ex.getMessage());

????? //System.out.println(" 連接關閉失敗 " + ex.getMessage());

??? }

? }

}

?

?

******** 包含常量的類 constants.java ，常量 ********

?

package page;

?

/**

?* 定義工程中公用的常量

?* <p>Title: 分頁 </p>

?* <p>Description: </p>

?* <p>Copyright: Copyright (c) 2005</p>

?* <p>Company: BCS</p>

?* @author Alex

?* @version 1.0

?*/

public final class constants {

? public static final int MAX_PAGE_INDEX = 5; // 頁腳顯示多少頁

? public static final int PAGE_SIZE = 2; // 每頁的記錄數

}

?

?

******** 測試 jsp 頁面 index.jsp ，為了方便測試，嵌入了 java 代碼，能顯示就行 ********

?

<%@ taglib uri="/WEB-INF/struts-logic.tld" prefix="logic" %>

<%@ taglib uri="/WEB-INF/struts-bean.tld" prefix="bean" %>

<%@ taglib uri="/WEB-INF/struts-html.tld" prefix="html" %>

<%@ page contentType="text/html; charset=GBK" import="java.util.*,page.*"%>

<html:html>

<head>

<title></title>

<style type="text/css">

.pt9 {? font: 10pt " 宋體 "}

body { font: 10pt " 宋體 " ; margin: 15px}

td {? font-size: 10pt}

a:hover {? font-size: 10pt; color: red; text-decoration: underline}

a:link {? font-size: 10pt; color: blue; text-decoration: underline}

a:active {? font-size: 10pt; color: blue; text-decoration: underline}

a:visited { font-size: 10pt; color: blue; text-decoration: underline }

</style>

</head>

<body bgcolor="#ffffff">

?

<p><a href="Show">http://localhost:8088/page/showEmp.do?offset=0">Show Me All Of The Emps</a></p>

?

<logic:present name="emps">

? <%

? ArrayList emps = (ArrayList)request.getAttribute("emps");

? Iterator it = emps.iterator();

? empVO empvo;

? while(it!=null && it.hasNext()){

??? empvo = (empVO)it.next();

??? out.print(empvo.getEmpno() + "? ");

??? out.print(empvo.getEname() + "<br>");

? }

??? out.print(" 當前頁有 " + emps.size() + " 條記錄 <br>");

??? out.print("<p>");

? %>

</logic:present>

?

<logic:present name="pager">

? <%

? Pager pager = (Pager)request.getAttribute("pager");

? out.print(pager.getPageNavigation() + "<p>");

? out.print(" 共有記錄 " + pager.getSize() + " 條 <br>");

? out.print(" 每頁有 " + pager.getLength() + " 條記錄 <br>");

? out.print(" 共分 " + pager.pageCount() + " 頁 <br>");

? %>

</logic:present>

</body>

</html:html>

?

******** 配置文件 struts-config.xml********

?

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

<!DOCTYPE struts-config PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.1//EN" "http://jakarta.apache.org/struts/dtds/struts-config_1_1.dtd">

<struts-config>

? <form-beans>

??? <form-bean name="empForm" type="page.empForm" />

? </form-beans>

? <action-mappings>

??? <action input="/index.jsp" name="empForm" path="/showEmp" scope="request" type="page.empAction" validate="false">

????? <forward name="faiure" path="/index.jsp" />

????? <forward name="success" path="/index.jsp" />

??? </action>

? </action-mappings>

</struts-config>

?