Struts分頁

拜讀了bibiye的《一個高效簡潔的Struts分頁方法(原創(chuàng))》后，根據(jù)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！

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

********分頁類Pager.java，負(fù)責(zé)生成分頁導(dǎo)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(dǎo)航條
   * @param offset int 起始記錄的位置
   * @param size int 總記錄數(shù)
   * @param length int 步長
   * @param url String .do的url
   * @param pageHeader String 導(dǎo)航條的前綴文字提示
   * @return String
   */
public String getPageNavigation() {
    String pageNavigation = ""; //最終返回的分頁導(dǎo)航條
    //記錄數(shù)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(jīng)包含了其他的參數(shù),就把offset參數(shù)接在后面
        pref = "&";
      }
      else {
        //如果url中沒有別的參數(shù)
        pref = "?";
      }
      //如果導(dǎo)航條包含header
      if (pageHeader != null && pageHeader.length() > 0) {
        pageNavigation = pageHeader + " : ";
      }
      //如果不是第一頁,導(dǎo)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(dǎo)航條中,排頭的那一頁的offset值
      int startOffset;
      //位于導(dǎo)航條中間的那一頁的offset值(半徑)
      int radius = constants.MAX_PAGE_INDEX / 2 * length;
      //如果當(dāng)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(dāng)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(dǎo)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(shù)
   * @param size int 總記錄數(shù)
   * @param length int 每頁的記錄數(shù)
   * @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(shù)
   * @param size int 總記錄數(shù)
   * @param length int 每頁的記錄數(shù)
   * @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(shù)
   * @param length int 每頁的記錄數(shù)
   * @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(shù)據(jù)處理類empDAO.java，負(fù)責(zé)訪問DB，獲取當(dāng)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(shù)據(jù)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(shù)
   * @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(yè)務(wù)類empBO.java，調(diào)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(shù)
   * @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(shù)
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(rèn)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(diào)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(jìn)來的起始記錄號
      int offset = ( (empForm) actionForm).getOffset();
      //獲取每頁的記錄數(shù)
      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(shù)(總記錄數(shù))
      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(dǎo)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(shù)據(jù)庫連接池類DBPool.java，可以使用tomcat的連接池，也可以不用，這里關(guān)閉了********

package page;

import java.sql.*;
import javax.naming.*;
import javax.sql.*;

import org.apache.commons.logging.*;

/**
* 系統(tǒng)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(shù)據(jù)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(shù)據(jù)源" + ex.getMessage());
    }
    catch (SQLException ex1) {
      log.error("Error Connection! " + ex1.getMessage());
      //System.out.println("錯誤的數(shù)據(jù)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(guān)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(shù)
}

********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">

<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(dāng)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" "<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>

posted on 2007-08-01 16:11 CoolYongZi 閱讀(289) 評論(0) 編輯收藏

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