說是struts分頁,實際上這個分頁類不局限在某個框架下用的
實現方法是通過list和 map 來封裝數據結果集省了建立formbean和手動對formbean賦值的麻煩，
用list和 map 來封裝后使用起來和rs基本上一樣，有些地方比RS方便些。
本分頁類中對查詢參數已經作了處理，所以不需要在自己在去拼URL參數了。
sql server分頁使用存儲過程要更高效些
下面這個存儲過程是從SQL區找到的
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CREATE Proc p_show
@QueryStr varchar(8000), --表名、視圖名、查詢語句
@PageSize int=10,?? --每頁的大小(行數)
@PageCurrent int=1,?? --要顯示的頁
@FdShow varchar (8000)='', --要顯示的字段列表,如果查詢結果有標識字段,需要指定此值,且不包含標識字段
@FdOrder nvarchar (3000)='' --排序字段列表
as
declare @FdName nvarchar(550) --表中的主鍵或表、臨時表中的標識列名
?,@Id1 varchar(80),@Id2 varchar(80) --開始和結束的記錄號
?,@Obj_ID int??? --對象ID
--表中有復合主鍵的處理
declare @strfd nvarchar(4000) --復合主鍵列表
?,@strjoin varchar(8000) --連接字段
?,@strwhere nvarchar(4000) --查詢條件
select @Obj_ID=object_id(@QueryStr)
?,@FdShow=case isnull(@FdShow,'') when '' then ' *' else ' '+@FdShow end
?,@FdOrder=case isnull(@FdOrder,'') when '' then '' else ' order by '+@FdOrder end
?,@QueryStr=case when @Obj_ID is not null then ' '+@QueryStr else ' ('+@QueryStr+') a' end
--如果顯示第一頁，可以直接用top來完成
if @PageCurrent=1
begin
?select @Id1=cast(@PageSize as varchar(50))
?exec('select top '+@Id1+@FdShow+' from '+@QueryStr+@FdOrder)
?return
end
--如果是表,則檢查表中是否有標識更或主鍵
if @Obj_ID is not null and objectproperty(@Obj_ID,'IsTable')=1
begin
?select @Id1=cast(@PageSize as varchar(50))
? ,@Id2=cast((@PageCurrent-1)*@PageSize as varchar(50))
?select @FdName=name from syscolumns where id=@Obj_ID and status=0x80
?if @@rowcount=0?? --如果表中無標識列,則檢查表中是否有主鍵
?begin
? if not exists(select 1 from sysobjects where parent_obj=@Obj_ID and xtype='PK')
?? goto lbusetemp? --如果表中無主鍵,則用臨時表處理
? select @FdName=name from syscolumns where id=@Obj_ID and colid in(
?? select colid from sysindexkeys where @Obj_ID=id and indid in(
??? select indid from sysindexes where @Obj_ID=id and name in(
???? select name from sysobjects where xtype='PK' and parent_obj=@Obj_ID
?? )))
? if @@rowcount>1? --檢查表中的主鍵是否為復合主鍵
? begin
?? select @strfd='',@strjoin='',@strwhere=''
?? select @strfd=@strfd+',['+name+']'
??? ,@strjoin=@strjoin+' and a.['+name+']=b.['+name+']'
??? ,@strwhere=@strwhere+' and b.['+name+'] is null'
??? from syscolumns where id=@Obj_ID and colid in(
??? select colid from sysindexkeys where @Obj_ID=id and indid in(
???? select indid from sysindexes where @Obj_ID=id and name in(
????? select name from sysobjects where xtype='PK' and parent_obj=@Obj_ID
??? )))
?? select @strfd=substring(@strfd,2,2000)
??? ,@strjoin=substring(@strjoin,5,4000)
??? ,@strwhere=substring(@strwhere,5,4000)
?? goto lbusepk
? end
?end
end
else
?goto lbusetemp
/*--使用標識列或主鍵為單一字段的處理方法--*/
lbuseidentity:
?exec('select top '+@Id1+@FdShow+' from '+@QueryStr
? +' where '+@FdName+' not in(select top '
? +@Id2+''+@FdName+' from '+@QueryStr+@FdOrder
? +')'+@FdOrder
? )
?return
/*--表中有復合主鍵的處理方法--*/
lbusepk:?
?exec('select '+@FdShow+' from(select top '+@Id1+' a.* from
? (select top 100 percent * from '+@QueryStr+@FdOrder+') a
? left join (select top '+@Id2+''+@strfd+'
? from '+@QueryStr+@FdOrder+') b on '+@strjoin+'
? where '+@strwhere+') a'
? )
?return
/*--用臨時表處理的方法--*/
lbusetemp:?
select @FdName='[ID_'+cast(newid() as varchar(80))+']'
?,@Id1=cast(@PageSize*(@PageCurrent-1) as varchar(50))
?,@Id2=cast(@PageSize*@PageCurrent-1 as varchar(50))
exec('select '+@FdName+'=identity(int,0,1),'+@FdShow+'
? into #tb from'+@QueryStr+@FdOrder+'
?select '+@FdShow+' from #tb where '+@FdName+' between '
?+@Id1+' and '+@Id2
?)
GO
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這里需要建立一個分頁類ResultGatherPro.java
相關說明在相應行的后面
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import conn.DBConnManager;//這個是連接池，可以更換其他的。
import javax.servlet.http.HttpServletRequest;
import java.sql.*;
import java.util.*;
public class ResultGatherPro {
??? private String sql;
??? private int intPageSize; //每頁行數
??? private int intRowCount;
??? private int intPageCount;
??? private int intPage; //頁號
??? private String Counter;
??? DBConnManager conn = null;
??? Connection con = null;
??? CallableStatement stmt = null;
??? ResultSet rs = null;
??? Statement st = null;
??? ResultSet rsc = null;
??? private String defaultname = "default";
??? public ResultGatherPro() {
??? }
??? public ResultGatherPro(String sqlcom, int rownum, int pagenum, String counter) {
??????? System.out.println(counter);
??????? sql = sqlcom;
??????? intPageSize = rownum;
??????? intPage = pagenum;
??????? Counter = counter;
??????? System.out.println(sqlcom);
??? }
??? public void setUseDB(String dbname)
??? {
??????? this.defaultname = dbname;
??? }
??? public List selectRS(String sqlcom, int rownum, int pagenum, String counter) {
??????? System.out.println(counter);
??????? this.sql = sqlcom;
??????? this.intPageSize = rownum;
??????? this.intPage = pagenum;
??????? this.Counter = counter;
??????? System.out.println(sqlcom);
??????? return selectRS();
??? }
??? public List selectRS() {
??????? List rsall = new ArrayList();
??????? Map rsTree;
??????? try {
??????????? conn = DBConnManager.getInstance();
??????????? con = conn.getConnection(defaultname);
??????????? st = con.createStatement();
??????????? rsc = st.executeQuery(Counter);
??????????? while (rsc.next()) {
??????????????? intRowCount = rsc.getInt("allrow");
??????????? }
??????????? stmt = con.prepareCall("{call p_show('" + sql + "'," + intPageSize + "," + intPage + ")}");//如果用別的數據庫就把這個地方修改一下
??????????? rs = stmt.executeQuery();
??????????? ResultSetMetaData rsmd = rs.getMetaData();
??????????? int numberOfColumns = rsmd.getColumnCount();
??????????? //Object[] aa = new Object[numberOfColumns-1];
??????????? intPageCount = (intRowCount + intPageSize - 1) / intPageSize;
??????????? while (rs.next()) {
??????????????? rsTree = new HashMap(numberOfColumns);
??????????????? for (int r = 1; r < numberOfColumns + 1; r++) {
??????????????????? rsTree.put(rsmd.getColumnName(r).toLowerCase(), rs.getObject(r));//toLowerCase()這個地方把列名轉化為小寫是為了和oracle兼容
??????????????? }
??????????????? rsall.add(rsTree);
??????????? }
??????? } catch (java.lang.Exception ex) {
??????????? System.out.println("db conn has a Exception !!!!");
??????????? if(ex.toString().indexOf("peer")>0||ex.toString().indexOf("reset")>0)?//一般連接池都沒有自動重連功能，這里是當數據庫連接異常后，進行重新初始化連接。不然即使網絡正常了，數據庫連接也不會恢復
??????????????? DBConnManager.reConnect();
??????????? ex.printStackTrace();
??????? } finally {
??????????? try {
??????????????? if (rsc != null)
??????????????????? rsc.close();
??????????????? if (st != null)
??????????????????? st.close();
??????????????? if (rs != null)
??????????????????? rs.close();
??????????????? if (stmt != null)
??????????????????? stmt.close();
??????????????? if (conn != null)
??????????????????? conn.releaseConnection(defaultname, con);
??????????? } catch (Exception e) {
??????????????? System.out.println(e);
??????????? }
??????? }
??????? return rsall;
??? }
??? public String ChangePage(HttpServletRequest request) {
??????? String urlchange = null;
??????? String pagename = request.getRequestURI().substring(request.getRequestURI().lastIndexOf("/") + 1);
??????? String url = getUrl(request);
??????? String dol = "";
??????? if (url != null && !url.equals(""))
??????????? dol = "&";
??????? if (intPage > 1 && intPage < intPageCount) {
??????????? urlchange = "<a href=" + pagename + "?pagenum=" + (intPage - 1) + dol + url + ">上一頁</a> | <a href=" + pagename + "?pagenum=" + (intPage + 1) + dol + url + ">下一頁</a> | 第" + intPage + "頁 | 共" + intPageCount + "頁 | 共" + intRowCount + "條";
??????? } else if (intPage == 1 && intRowCount <= intPageSize) {
??????????? urlchange = "上一頁 | 下一頁 | 第" + intPage + "頁 | 共" + intPageCount + "頁 | 共" + intRowCount + "條";
??????? } else if (intPage == intPageCount && intPage != 1) {
??????????? urlchange = "<a href=" + pagename + "?pagenum=" + (intPage - 1) + dol + url + ">上一頁</a> 下一頁 | 第" + intPage + "頁 | 共" + intPageCount + "頁 | 共" + intRowCount + "條";
??????? } else if (intPage == 1 && intRowCount >= intPageSize) {
??????????? urlchange = "上一頁 | <a href=" + pagename + "?pagenum=" + (intPage + 1) + dol + url + ">下一頁</a> | 第" + intPage + "頁 | 共" + intPageCount + "頁 | 共" + intRowCount + "條";
??????? } else {
??????????? urlchange = "<a href=" + pagename + ">第一頁</a>";
??????? }
??????? return urlchange;
??? }
??? public String ChangeBar(HttpServletRequest request) {
??????? String urlchange = null;
??????? String pagename = request.getRequestURI().substring(request.getRequestURI().lastIndexOf("/") + 1);
??????? String url = getUrl(request);
??????? String dol = "";
??????? if (url != null && !url.equals(""))
??????????? dol = "&";
??????? if (intPage > 1 && intPage < intPageCount) {
??????????? urlchange = "<a href=" + pagename + "?pagenum=" + (intPage - 1) + dol + url + ">上一頁</a> | <a href=" + pagename + "?pagenum=" + (intPage + 1) + dol + url + ">下一頁</a> | 第" + intPage + "頁 | 共" + intPageCount + "頁";
??????? } else if (intPage == 1 && intRowCount <= intPageSize) {
??????????? urlchange = "上一頁 | 下一頁 | 第" + intPage + "頁 | 共" + intPageCount + "頁";
??????? } else if (intPage == intPageCount && intPage != 1) {
??????????? urlchange = "<a href=" + pagename + "?pagenum=" + (intPage - 1) + dol + url + ">上一頁</a> 下一頁 | 第" + intPage + "頁 | 共" + intPageCount + "頁";
??????? } else if (intPage == 1 && intRowCount >= intPageSize) {
??????????? urlchange = "上一頁 | <a href=" + pagename + "?pagenum=" + (intPage + 1) + dol + url + ">下一頁</a> | 第" + intPage + "頁 | 共" + intPageCount + "頁";
??????? } else {
??????????? urlchange = "<a href=" + pagename + ">第一頁</a>";
??????? }
??????? return urlchange;
??? }
??? public int getTotal() {
??????? return intRowCount;
??? }
??? public int getPageCount() {
??????? return intPageCount;
??? }
??? public String gotoPage(HttpServletRequest request) {
??????? String url = getUrl(request);
??????? String javascript = "<script>function checksearch(sform)\n{if(sform.pagenum.value==\"\" || sform.pagenum.value==\"0\"){alert('請輸正確入頁數！');sform.pagenum.focus();return false;}\nif(isNaN(sform.pagenum.value)){alert('請輸入數字！');sform.pagenum.focus();return false;}}</script>";
??????? String form = "<table? border='0' cellpadding='0' cellspacing='0'>\n" + javascript;
??????? form += "<form?? action='' onSubmit='return checksearch(this)'>\n<tr><td width='40' align='center'>\n<input name='pagenum' type='text' size='3' class='gotext'>\n ";
??????? if (url != null) {
??????????? if (url.indexOf("&") > 0) {
??????????????? String[] param = new String[(url.split("&")).length];
??????????????? param = url.split("&");
??????????????? for (int i = 0; i < param.length; i++) {
??????????????????? form += "<input type='hidden' name='" + param[i].substring(0, param[i].indexOf("=")) + "' value='" + param[i].substring(param[i].indexOf("=") + 1) + "'>\n";
??????????????? }
??????????? } else {
??????????????? if (url.indexOf("=") > 0) {
??????????????????? form += "<input type='hidden' name='" + url.substring(0, url.indexOf("=")) + "' value='" + url.substring(url.indexOf("=") + 1) + "'>\n";
??????????????? }
??????????? }
??????? }
??????? form += "</td><td width='25' align='center'><input type='submit' name='Submit' value='GO' class='gobtn'>\n</td>\n</tr>\n</form>\n</table>";
??????? return form;
??? }
??? private String getUrl(HttpServletRequest request) {
??????? String url = "";
??????? Enumeration param = request.getParameterNames();
??????? while (param.hasMoreElements()) {
??????????? String pname = param.nextElement().toString();
??????????? if (!pname.equalsIgnoreCase("pagenum") && !pname.equalsIgnoreCase("submit"))
??????????????? url += pname + "=" + request.getParameter(pname) + "&";
??????? }
??????? if (url.endsWith("&")) {
??????????? url = url.substring(0, url.lastIndexOf("&"));
??????? }
??????? return url;
??? }
??? public String intercept(String str, int num, String last) {
??????? if (str.length() <= num)
??????????? return str;
??????? else
??????????? return str.substring(0, num) + last;
??? }
}
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在action里可以這樣調用
可以看到action里沒有做對傳遞參數的處理，只需要把request整個傳到分頁類里就可以了
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???String sql = "select top 100 percent * from usertable";
???String sqlcount = "select count(*) from usertable";//為了得到總行數
???int pagesize= 18;
???int pagenum = 1;
???if(request.getParameter("pagenum")!=null)
???{
????pagenum = java.lang.Integer.parseInt(request.getParameter("pagenum"));
???}
???ResultGatherPro rs = new ResultGatherPro(sql,pagesize,pagenum,sqlcount);
???request.setAttribute("liststill",rs.selectRS());
???request.setAttribute("changepage",rs.ChangePage(request));
???request.setAttribute("gotopage",rs.gotoPage(request));
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最后 jsp里可以這樣寫
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<logic:iterate id="listuser" name="liststill" type="Map">
<bean:write name='listuser' property='username'/>???
<bean:write name='listuser' property='useremail'/>??????
</logic:iterate>
<bean:write name='changepage' filter="false"/>?
??????????????? <bean:write name='gotopage' filter="false"/>
上面兩個一定要設置filter="false" 不然會過濾html部分
如果用mysql數據庫
將分頁類中
con.prepareCall("{call p_show('" + sql + "'," + intPageSize + "," + intPage + ")}");
改成
con.prepareCall(sql+" limit "+(intPage-1)*intPageSize+","+intPageSize);
如果用oracle數據庫
改成
con.prepareCall("SELECT * FROM(SELECT A.*, rownum r FROM("+sql+") A WHERE rownum <= "+intPage*intPageSize+") B WHERE r > "+(intPage-1)
*intPageSize);
最好不要用把所有記錄都讀出來然后在其中進行分頁的方法