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！
?
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。
?
********
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>
?
posted on 2007-08-10 11:42
蠻哥♂楓 閱讀(295)
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