原貼地址:http://www.aygfsteel.com/Jkallen/archive/2006/03/13/35110.html
發(fā)現(xiàn)在系統(tǒng)中有好多寫得很好的代碼,也不知道是哪位前輩留下來的.整理一下...
自定義分頁標簽庫
1:在配置文件中配置
<!--?self?Tag?Library?Descriptors?-->
??<taglib>
????<taglib-uri>/WEB-INF/self-html.tld</taglib-uri>
????<taglib-location>/WEB-INF/self-html.tld</taglib-location>
??</taglib>2:在self-html.tld中page標簽的配置
<tag>
????????<name>page</name>
????????<tagclass>com.jbbis.netedu.common.util.taglib.PageTag</tagclass>
????????<bodycontent>empty</bodycontent>
????????<info>tag?here</info>
????????<attribute>
????????<name>name</name>
????????<required>true</required>
????????<rtexprvalue>false</rtexprvalue>
????????</attribute>????
????????<attribute>
????????<name>pageNum</name>
????????<required>false</required>
????????<rtexprvalue>false</rtexprvalue>
????????</attribute>????????
????????<attribute>
????????<name>method</name>
????????<required>false</required>
????????<rtexprvalue>false</rtexprvalue>
????????</attribute>????
????????<attribute>
????????<name>methodValue</name>
????????<required>false</required>
????????<rtexprvalue>true</rtexprvalue>
????????</attribute>????
????????<attribute>
????????<name>form</name>
????????<required>true</required>
????????<rtexprvalue>false</rtexprvalue>
????????</attribute>????????
????????<attribute>
????????<name>action</name>
????????<required>flase</required>
????????<rtexprvalue>true</rtexprvalue>
????????</attribute>
????????<attribute>
????????<name>returnLevel</name>
????????<required>flase</required>
????????<rtexprvalue>true</rtexprvalue>
????????</attribute>????????????????????????????????????
????</tag> 其實從這兒也可以看到在PageTag文件中是一些什么值了...
3:PageTag中的具體操作(精華全部在這兒啦)
/**//*
?*?Created?on?2004-6-25
?*
?*/
package?com.jbbis.netedu.common.util.taglib;
import?java.io.IOException;
import?javax.servlet.jsp.JspException;
import?javax.servlet.jsp.JspWriter;
import?javax.servlet.jsp.tagext.TagSupport;
import?com.jbbis.netedu.common.page.NullPage;
import?com.jbbis.netedu.common.page.Page;
/**?*//**
?*?@author?leo_deng
?*
?*/
public?class?PageTag?extends?TagSupport?
{
????
????/**//*?(non-Javadoc)
?????*?@see?javax.servlet.jsp.tagext.Tag#doStartTag()
?????*/
????private?String?name;
????private?String?pageNum="pageNum";
????private?String?method="method";
????private?String?methodValue;
????private?String?form="mainForm";
????private?String?action;
????private?String?returnLevel;
????
????private?final?int?CONST_FIRST=1;
????private?final?int?CONST_NEXT=2;
????private?final?int?CONST_PRIOR=3;
????private?final?int?CONST_LAST=4;
????
????
????
????
????public?int?doStartTag()?throws?JspException?{
????????//?TODO?Auto-generated?method?stub
????????try{
????????????JspWriter?out?=?pageContext.getOut()?;
????????????Page?page=(Page)pageContext.getRequest().getAttribute(name);
????????????if(page==null)
????????????????page=NullPage.instance();
????????????out.print(getHtml(page.getPageNumber(),page.getPageCount()));
????????????out.print(getJs(page.getPageNumber(),page.getPageCount()));
????????????//jspwriter是一個隱含對象，用于向jsp網(wǎng)頁輸出內(nèi)容。輸出的目標由
????????????//?pagecontext.getout提供
????????????
????????????//向jsp網(wǎng)頁上下文輸出
??????????}catch(IOException?ioException){
????????????throw?new?JspException(ioException.getMessage()?);
??????????}//catch
??????????return(SKIP_BODY);
????}
????/**//*
?????*?<
?????*?<!--
?????*?function?page_next(){
?????*??form.action=""
?????*?????form.pageNum=""
?????*?????form.method.value=""
?????*?????form.submit;
?????*?
?????*?}
?????*?function?page_prior()
?????*?function?page_first()
?????*?funciotn?page_last()
?????*?
?????*?//-->
?????*?<div?class="listbox_page">
????????????<a?class="page"?><img?src="public/icon/first.gif"?alt="首頁"?align="absmiddle"?border="0"?onclick="page_first()"/></a>
????????????<a?class="page"?><img?src="public/icon/previous.gif"?alt="上頁"?align="absmiddle"?border="0"?onclick="page_first()"/></a>
????????????第<input?class="page_number"?name="pageNum"?value="">????<img?src="page_go.gif"?class="page_go">頁
????????????<a?class="page"?><img?src="public/icon/next.gif"?alt="下頁"?align="absmiddle"?border="0"/?onclick="page_next()"></a>
????????????<a?class="page"?><img?src="public/icon/last.gif"?alt="末頁"?align="absmiddle"?border="0"/?onclick="page_prior()"></a>
????????????共?<span?class="page_sum">1000</span>?頁?
????????</div>
?????*
?????*?*/
????private?String?getJs(int?pageNum,int?totalNum){
????????StringBuffer?sb=new?StringBuffer();
????????sb.append("\n<script?language=\"JavaScript\">\n<!--");
????????????sb.append(printFunction("page_first",pageNum,totalNum,CONST_FIRST));
????????????sb.append(printFunction("page_next",pageNum,totalNum,CONST_NEXT));
????????????sb.append(printFunction("page_prior",pageNum,totalNum,CONST_PRIOR));
????????????sb.append(printFunction("page_last",pageNum,totalNum,CONST_LAST));
????????????getGoJs(sb,pageNum,totalNum);
????????sb.append("\n?//-->\n</script>");
????????return?sb.toString();
????}
????private?void?getGoJs(StringBuffer?sb,int?pageNum,int?totalNum){
????????sb.append("function?page_go(obj){\n");
????????sb.append("var?page_number=document.getElementById(\"page_number\");\n");
????????sb.append("if(?page_number.value?!=?new?Number(page_number.value))return?alert(\"請輸入正確的頁數(shù)\");\n");
????????sb.append("if(page_number.value<1)?page_number.value=1;if(page_number.value>");
????????sb.append(totalNum);
????????sb.append(")page_number.value=");
????????sb.append(totalNum);
????????sb.append(";\n");
????????sb.append("if(page_number.value!="+pageNum+")");
????????sb.append("submitForPageNum(obj);\n");
????????sb.append("}");
????}
????private?StringBuffer?printFunction(String?function,int?pageNumber,int?totalNumber,int?pageConst){
????????StringBuffer?sb=new?StringBuffer();
????????sb.append("\nfunction?"+function+"(){");
????????sb.append("\nevent.returnValue=false;");
????????sb.append(printAction());
????????sb.append(printMethod());
????????//sb.append("\n"+this.form+".submit();\n}");
????????if(totalNumber>1){
????????????switch(pageConst){
????????????????case?CONST_FIRST:
????????????????????if(pageNumber>1){
????????????????????????sb.append(printPageNum(String.valueOf(1)));
????????????????????????sb.append("\n?submitForPageNum("+this.form+");");
????????????????????}
????????????????????break;
????????????????case?CONST_LAST:
????????????????????if(pageNumber<totalNumber){
????????????????????????sb.append(printPageNum(String.valueOf(totalNumber)));
????????????????????????sb.append("\n?submitForPageNum("+this.form+");");
????????????????????}
????????????????????break;
????????????????case?CONST_PRIOR:
????????????????????if(pageNumber>1){
????????????????????????sb.append(printPageNum(String.valueOf(pageNumber-1)));
????????????????????????sb.append("\n?submitForPageNum("+this.form+");");
????????????????????}
????????????????????break;????????????????????????
????????????????case?CONST_NEXT:
????????????????????if(pageNumber<totalNumber){
????????????????????????sb.append(printPageNum(String.valueOf(pageNumber+1)));
????????????????????????sb.append("\n?submitForPageNum("+this.form+");");
????????????????????}
????????????????????break;
????????????}
????????}
????????
????????sb.append("\n}");
????????return?sb;????????
????}
????/**//*
????private?StringBuffer?printFunction(String?function,String?pageNum,int?pageConst){
????????StringBuffer?sb=new?StringBuffer();
????????sb.append("\nfunction?"+function+"(){");
????????sb.append("\nevent.returnValue=false;");
????????sb.append(printAction());
????????sb.append(printMethod());
????????sb.append(printPageNum(pageNum));
????????//sb.append("\n"+this.form+".submit();\n}");
????????????????
????????????????sb.append("\n?submitForPageNum("+this.form+");\n}");
????????
????????sb.append("\n}");
????????
????????return?sb;
????}
????*/
????private?String?printAction(){
????????if(this.action!=null)
????????????return?("\n"+this.form+".action=\""+action+"\";");
????????else
????????????return?"";
????}
????private?String?printMethod(){
????????if(this.methodValue!=null)
????????????return?("\n"+this.form+"."+this.method+".value=\""+this.methodValue+"\";");
????????else
????????????return?"";
????}????
????private?String?printPageNum(String?num){
????????return?"\n"+this.form+"."+this.pageNum+".value=\""+num+"\";";
????}
????private?String?getHtml(int?pageNum,int?totalNum){
????????StringBuffer?sb=new?StringBuffer();
????????sb.append("\n<a?class=\"page\"?href=\"javascript:void(0)\"?onclick=\"page_first()\"?><img?src=\"public/icon/first.gif\"?alt=\"首頁\"?align=\"absmiddle\"?border=\"0\"?/></a>");
????????sb.append("\n<a?class=\"page\"?href='javascript:void(0)'?onclick='page_prior()'?><img?src=\"public/icon/previous.gif\"?alt=\"上頁\"?align=\"absmiddle\"?border=\"0\"?/></a>");
????????sb.append("\n第<input?id=\"page_number\"?class=\"page_number\"?name=\"pageNum\"?value=\"");
????????sb.append(String.valueOf(pageNum));
????????sb.append("\"><button?class='page_go'?onclick='page_go(this.form);'></button>頁????");
????????//sb.append(""<img?src=\"page_go.gif\"?class=\"page_go\">");
????????sb.append("\n<a?class=\"page\"?href=\"javascript:void(0)\"?onclick=\"page_next()\"><img?src=\"public/icon/next_page.gif\"?alt=\"下頁\"?align=\"absmiddle\"?border=\"0\"/></a>");
????????sb.append("\n<a?class=\"page\"?href=\"javascript:void(0)\"?onclick=\"page_last()\"><img?src=\"public/icon/last.gif\"?alt=\"末頁\"?align=\"absmiddle\"?border=\"0\"/></a>");
????????sb.append("\n共?<span?class=\"page_sum\">");
????????sb.append(String.valueOf(totalNum));
????????sb.append("</span>?頁");
????????return?sb.toString();
????}
????/**?*//**
?????*?@return?Returns?the?pageNum.
?????*/
????public?String?getPageNum()?{
????????return?pageNum;
????}
... ....(other getter and setter method ^_^)????
}
4:在JSP布面中導入:
<%@?taglib?uri="/WEB-INF/self-html.tld"?prefix="netedu"?%> 5:在JSP頁面中引用:
<form?name="newsForm"?method="post"?action="<%=request.getContextPath()?%>/portal/newsAction.page"?id="newsForm">
<!--?TIP008:
??翻頁部分
?-->
???<div?class="listbox_page">
????<netedu:page?name="page"?form="newsForm"?/>
???</div>
<!--?TIP008:END-->
?</form> 6:page文件
/**//*
?*?Created?on?2004-6-8
?*/
package?com.jbbis.netedu.common.page;
import?java.util.Collection;
/**?*//**
?*?分頁表示?Bean
?*?用于前臺顯示分頁數(shù)據(jù)
?*?@author?qqs
?*/
public?interface?Page?{
??/**?*//**
???*?whether?or?not?is?the?last?page?of?list?data
???*?是否為最后一頁
???*?@return
???*/
??public?boolean?isLast();
??/**?*//**
???*?是否為第一頁
???*?@return
???*/
??public?boolean?isFirst();
??/**?*//**
???*?List?of?page?data
???*?@return?Page?data
???*/
??public?Collection?getData();
??
??/**?*//**
???*?List?of?page?data
???*?@return?Page?data
???*/
??public?void?setData(Collection?data);
??/**?*//**
???*?當前頁數(shù)
???*?@return?Page?Number
???*/
??public?int?getPageNumber();
??/**?*//**
???*?Next?page?number
???*?if?current?page??is?the?first?page?then
???*???return?0;
???*?else
???*???return?pageNumber+1;
???*?下一頁的頁數(shù)
???*?
???*?@return?next?page?number
???*/
??public?int?getNextPageNumber();
??/**?*//**
???*?前一頁的頁數(shù)
???*?if?previous?pge?lest?than?last?the?first?page?then
???*???return?0
???*?esle
???*???return?PageNumber?-?1
???*?@return?previous?page?number
???*/
??public?int?getPrevPageNumber();
??/**?*//**
???*?Current?page?size
???*?當前頁的記錄數(shù)
???*?@return?Current?page?size
???*/
??public?int?getSize();
??/**?*//**
???*?Page?size
???*?定義的每頁的頁數(shù)
???*?@return
???*/
??public?int?getPageSize();
??/**?*//**
???*?Total?pages?count
???*?總頁數(shù)
???*?@return?Total?pages?count
???*/
??public?int?getPageCount();
??/**?*//**
???*?當前頁中第一條記錄在數(shù)據(jù)庫中的順序
???*?get?index?of?the?first?data?of?the?page
???*?@return?index?of?the?first?data?of?the?page
???*/
??public?int?getStartIndex();
??/**?*//**
???*?get?index?of?the?last?data?of?the?page
???*?當頁的最后一條記錄在數(shù)據(jù)庫中的順序
???*?@return?index?of?the?first?data?of?the?page
???*/
??public?int?getEndIndex();
??/**?*//**
???*?總的記錄數(shù)
???*?@return
???*/
??public?int?getTotalSize();
??/**?*//**
???*?是否為空頁
???*?@return
???*/
??public?boolean?isNull();
}7:其它
7.1
可以注意到在標簽的定義文件中用到了名為page_go的css層來美化界面,可能是出于滿足不同用戶對界面的不同要求所以在此沒有對此css定義,你可以在JSP布面中重寫此css.這兒有個可以參考一下.
下載7.2
根據(jù)標簽的定義可以看到,此page應該放到form中.
7.3
根據(jù)在標簽庫中的
Page?page=(Page)pageContext.getRequest().getAttribute(name); 語句,可見page應該在request.setAttribute("pageattribute",page);中定義.
7.4
如何通過對DB的操作得到了page ?通過DB操作可以獲得一系統(tǒng)的data(應該注意到了在page文件夾中有個data屬性,高人就是高人^_^),當然在得到這些data之前,先可能得進行一系統(tǒng)邏輯處理,比如說當前頁碼(pagenum),頁長(pagesize)等等.通過這些數(shù)據(jù)就可以得到一個page實例了! ~ ~ :?)
在上一個介紹里面主要講到了分頁標簽的配置，邏輯處理，引用。
我們在action中：
//JSP中引用此attribute分頁處理
request.setAttribute("page",page);
然后在JSP中引用此page。
這次主要看如何能過對DB操作實現(xiàn)此page。
處理邏輯：
1：根據(jù)SQL語句，當前頁面，頁面大小等參數(shù)，得到一系統(tǒng)data。
2：根據(jù)得到的data，再加上當前頁面，頁面大小可以實例化一個page類實體。
3：將此實體轉換成便于到前臺顯示的DTO。
具體如下：
首先，我們根據(jù)查詢語句從DB中得到一系列相關數(shù)據(jù)
可以看到其中除了createQuery，setFirstResult，setMaxResults外其實都是用戶自定義的一些函數(shù)。
其它函數(shù)，顧名思義應該知道它想實現(xiàn)一個什么功能，象doQuery(query)就是得到一個結果集也許是得到一個按列表方式抽取結果集?query.list(),or 按迭代方式抽取結果集query.iterate().函數(shù)getStartIndex（args[]）返回數(shù)據(jù)第一條記錄的起點位置。其它的也都差不多！
其次得到一個page的實體類（entity）,或者說得到其DAO對象。
其實得到一個DTO的page對象比較簡單。前面列出了page，而上面已經(jīng)從DB中得到了一系列數(shù)據(jù)（data),再加上頁面的相關信息就可以實例化一個page實體了：
.
public?DefaultPage(int?pageSize,?int?pagesCount,?int?pageNumber,?Collection?data,
?????????????????????int?totalSize)?{
????this.pageSize?=?pageSize;
????this.pagesCount?=?pagesCount;
????this.pageNumber?=?pageNumber;
????this.totalSize?=?totalSize;
????this.data?=?data;
??}
.
當然在此前，對面頁數(shù)據(jù)得處理一下，象pageNumber可能如下：
/**?*//**
?????*?@param?pageNumber
?????*?@param?pageSize
?????*?@param?totalCount
?????*?Return?PageNumber
?????*/
????protected?static?int?calcPageNumber(int?pageNumber,?int?pageSize,?int?totalCount)?{
????????int?maxPageNumber?=?calcMaxPageNumber(pageSize,?totalCount);
????????
????????pageNumber?=?pageNumber>maxPageNumber?maxPageNumber:pageNumber;
????????
????????if(pageNumber<=0)
????????????pageNumber=1;
????????
????????return?pageNumber;
????}
easy吧！
最后將此實體轉換成適合前臺顯示的DTO對象。
這個側是依據(jù)不同的需求去做相應的轉換了，一般來說從DB取出來的實體（DAO）直接與DB中的數(shù)據(jù)對應。而在DTO中我們可以提供許多更加符合實際的字段與方法，使得我們的JSP頁面顯示更加得心應手！同時也避免了直與DB交互。它們之間的關系，我亂七八糟寫過些東西（歡迎指正！）。
“一般人的標簽我不看，高手寫的東西真的值得借鑒，學習！”
posted on 2006-08-09 11:11
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