為我們的項目寫的一個輕量的分頁API。目的在于將分頁與數據查詢的邏輯完全剝離。我以前看過robbin發的通過detachedCriteria實現的分頁那片貼子，里面把分頁和數據查詢結合在一起了。而我覺得分開更輕量，而且替換也比較容易。但是這個實現中有一個反模式，在邏輯中生成了代碼，無奈之選，為了簡便。其中字符生成可以自己擴展i18n實現，應該非常容易。
分頁實現的接口：
package?com.goldnet.framework.util.paging;
/**?*//**
?*?分頁操作的接口
?*?@author?Tin
?*/
public?interface?IPagination?
{
????/**?*//**
?????*?默認的分頁大小
?????*/
????public?static?final?int?DEFAULT_PAGE_SIZE?=?15;
????/**?*//**
?????*?默認的分頁參數，指URL中用到的參數名
?????*/
????public?static?final?String?PAGE_SIZE_KEY?=?"pageSize";
????/**?*//**
?????*?默認的頁碼參數，指URL中用到的參數名
?????*/
????public?static?final?String?PAGE_NO_KEY?=?"pageno";
????/**?*//**
?????*?獲取總頁數
?????*?@return?總頁數
?????*/
????int?getPageSum();
????/**?*//**
?????*?下一頁的頁碼
?????*?@return
?????*/
????int?getNextPageNo();
????/**?*//**
?????*?上一頁的頁碼
?????*?@return
?????*/
????int?getPrevPageNo();
????/**?*//**
?????*?是否有下一頁，即是否為最后一頁
?????*?@return?是否有下一頁
?????*/
????boolean?hasNextPage();
????/**?*//**
?????*?是否有上一頁，即是否為第一頁
?????*?@return?是否有上一頁
?????*/
????boolean?hasPrevPage();
????/**?*//**
?????*?添加參數名稱、值對，如果頁面需要使用parameters傳遞分頁外的附加參數
?????*?@param?parameterName?參數名
?????*?@param?parameterValue?參數值
?????*/
????void?addPageParameter(String?parameterName,?String?parameterValue);
????String?getPageUrl();
????String?getPageHtmlStr();
????int?getItemSum();
????void?setItemSum(int?itemSum);
????String?getPageExtension();
????void?setPageExtension(String?pageExtension);
????String?getPageName();
????void?setPageName(String?pageName);
????int?getPageNo();
????void?setPageNo(int?pageNo);
????int?getPageSize();
????void?setPageSize(int?pageSize);
}抽象基類：
/**?*//**
?*
?*/
package?com.goldnet.framework.util.paging;
import?java.util.Iterator;
import?java.util.LinkedList;
import?java.util.List;
/**?*//**
?*?對PagingString的重構
?*?@author?Tin
?*
?*/
public?abstract?class?AbstractPagination?implements?IPagination?{
????/**?*//**
?????*?Page上顯示的List中的domainModel的總數
?????*/
????protected?int?itemSum?=?-1;
????/**?*//**
?????*?分頁的大小
?????*/
????protected?int?pageSize?=?DEFAULT_PAGE_SIZE;
????/**?*//**
?????*?頁數
?????*/
????protected?int?pageNo?=?0;
????/**?*//**
?????*?分頁的頁面的相對URL，不包括后綴
?????*/
????protected?String?pageName?=?null;
????/**?*//**
?????*?頁面的URL的后綴
?????*/
????protected?String?pageExtension?=?".action";
????/**?*//**
?????*?參數列表
?????*/
????protected?List<PageParameter>?parameterList?=?new?LinkedList<PageParameter>();
????/**?*//**
?????????*?返回的分頁信息的字符串
?????????*/
????protected?String?pageHtmlStr?=?null;
????/**?*//**
?????*?默認的構造函數
?????*?@param?pageName?分頁的頁面的相對URL，不包括后綴
?????*?@param?pageExtension?頁面的URL的后綴
?????*?@param?itemSum?Page上顯示的List中的domainModel的總數
?????*?@param?pageNo?頁數
?????*?@param?pageSize?分頁的大小
?????*/
????public?AbstractPagination(String?pageName,?String?pageExtension,
????????int?itemSum,?int?pageNo,?int?pageSize)?{
????????super();
????????this.pageName?=?pageName;
????????this.pageExtension?=?pageExtension;
????????this.itemSum?=?itemSum;
????????this.pageNo?=?pageNo;
????????this.pageSize?=?pageSize;
????}
????/**?*//**
?????*?無PageSize構造函數，使用默認PageSize為15
?????*?@param?pageName?分頁的頁面的相對URL，不包括后綴
?????*?@param?pageExtension?頁面的URL的后綴
?????*?@param?itemSum?Page上顯示的List中的domainModel的總數
?????*?@param?pageNo?頁數
?????*/
????public?AbstractPagination(String?pageName,?String?pageExtension,
????????int?itemSum,?int?pageNo)?{
????????super();
????????this.pageName?=?pageName;
????????this.pageExtension?=?pageExtension;
????????this.itemSum?=?itemSum;
????????this.pageNo?=?pageNo;
????}
????/**//*?(non-Javadoc)
?????*?@see?com.goldnet.framework.util.paging.IPagination#getPageSum()
?????*/
????public?int?getPageSum()?{
????????if?((itemSum?!=?-1)?&&?(pageSize?>?0))?{
????????????return?((itemSum?%?pageSize)?==?0)???(itemSum?/?pageSize)
???????????????????????????????????????????????:?((itemSum?/?pageSize)?+?1);
????????}
????????return?0;
????}
????/**//*?(non-Javadoc)
?????*?@see?com.goldnet.framework.util.paging.IPagination#getNextPageNo()
?????*/
????public?int?getNextPageNo()?{
????????return?(pageNo?<?(getPageSum()?-?1))???(pageNo?+?1)?:?(getPageSum()?-
????????1);
????}
????/**//*?(non-Javadoc)
?????*?@see?com.goldnet.framework.util.paging.IPagination#getPrevPageNo()
?????*/
????public?int?getPrevPageNo()?{
????????return?(pageNo?>?0)???(pageNo?-?1)?:?0;
????}
????/**//*?(non-Javadoc)
?????*?@see?com.goldnet.framework.util.paging.IPagination#hasNextPage()
?????*/
????public?boolean?hasNextPage()?{
????????if?(getPageSum()?<=?pageNo)?{
????????????return?false;
????????}
????????return?true;
????}
????/**//*?(non-Javadoc)
?????*?@see?com.goldnet.framework.util.paging.IPagination#hasPrevPage()
?????*/
????public?boolean?hasPrevPage()?{
????????if?(pageNo?<=?0)?{
????????????return?false;
????????}
????????return?true;
????}
????/**//*?(non-Javadoc)
?????*?@see?com.goldnet.framework.util.paging.IPagination#addPageParameter(java.lang.String,?java.lang.String)
?????*/
????public?void?addPageParameter(String?parameterName,?String?parameterValue)?{
????????PageParameter?pp?=?new?PageParameter(parameterName,?parameterValue);
????????this.parameterList.add(pp);
????}
????/**//*?(non-Javadoc)
?????*?@see?com.goldnet.framework.util.paging.IPagination#getPageUrl()
?????*/
????public?String?getPageUrl()?{
????????String?url?=?pageName?+?pageExtension;
????????if?(parameterList.size()?>?0)?{
????????????Iterator<PageParameter>?iterator?=?parameterList.iterator();
????????????PageParameter?pageFirstParameter?=?iterator.next();
????????????url?+=?("?"?+?pageFirstParameter.getParameterName()?+?"="?+
????????????pageFirstParameter.getParameterValue());
????????????while?(iterator.hasNext())?{
????????????????PageParameter?pageParameter?=?iterator.next();
????????????????url?+=?("&"?+?pageParameter.getParameterName()?+?"="?+
????????????????pageParameter.getParameterValue());
????????????}
????????}?else?{
????????????//補充一個?解決附加分頁參數時無?的問題
????????????url?+=?"?";
????????}
????????if?(pageSize?!=?DEFAULT_PAGE_SIZE)?{
????????????url?+=?("&"?+?PAGE_SIZE_KEY?+?"="?+?pageSize);
????????}
????????return?url;
????}
????/**?*//**
?????*?子類必須覆蓋的方法，用來計算分頁的字符的方法
?????*/
????public?abstract?void?compilePaginationString();
????/**?*//**
?????*?Getters?&?Setters
?????*/
????/**//*?(non-Javadoc)
?????*?@see?com.goldnet.framework.util.paging.IPagination#getPageHtmlStr()
?????*/
????public?String?getPageHtmlStr()?{
????????compilePaginationString();
????????return?pageHtmlStr;
????}
????/**//*?(non-Javadoc)
?????*?@see?com.goldnet.framework.util.paging.IPagination#getItemSum()
?????*/
????public?int?getItemSum()?{
????????return?itemSum;
????}
????/**//*?(non-Javadoc)
?????*?@see?com.goldnet.framework.util.paging.IPagination#setItemSum(int)
?????*/
????public?void?setItemSum(int?itemSum)?{
????????this.itemSum?=?itemSum;
????}
????/**//*?(non-Javadoc)
?????*?@see?com.goldnet.framework.util.paging.IPagination#getPageExtension()
?????*/
????public?String?getPageExtension()?{
????????return?pageExtension;
????}
????/**//*?(non-Javadoc)
?????*?@see?com.goldnet.framework.util.paging.IPagination#setPageExtension(java.lang.String)
?????*/
????public?void?setPageExtension(String?pageExtension)?{
????????this.pageExtension?=?pageExtension;
????}
????/**//*?(non-Javadoc)
?????*?@see?com.goldnet.framework.util.paging.IPagination#getPageName()
?????*/
????public?String?getPageName()?{
????????return?pageName;
????}
????/**//*?(non-Javadoc)
?????*?@see?com.goldnet.framework.util.paging.IPagination#setPageName(java.lang.String)
?????*/
????public?void?setPageName(String?pageName)?{
????????this.pageName?=?pageName;
????}
????/**//*?(non-Javadoc)
?????*?@see?com.goldnet.framework.util.paging.IPagination#getPageNo()
?????*/
????public?int?getPageNo()?{
????????return?pageNo;
????}
????/**//*?(non-Javadoc)
?????*?@see?com.goldnet.framework.util.paging.IPagination#setPageNo(int)
?????*/
????public?void?setPageNo(int?pageNo)?{
????????this.pageNo?=?pageNo;
????}
????/**//*?(non-Javadoc)
?????*?@see?com.goldnet.framework.util.paging.IPagination#getPageSize()
?????*/
????public?int?getPageSize()?{
????????return?pageSize;
????}
????/**//*?(non-Javadoc)
?????*?@see?com.goldnet.framework.util.paging.IPagination#setPageSize(int)
?????*/
????public?void?setPageSize(int?pageSize)?{
????????this.pageSize?=?pageSize;
????}
????public?List<PageParameter>?getParameterList()?{
????????return?parameterList;
????}
????public?void?setParameterList(List<PageParameter>?parameterList)?{
????????this.parameterList?=?parameterList;
????}
????/**?*//**
?????*?分頁參數，頁面的QueryString形式都是?parameter=value的形式，此處為一對
?????*?數據的抽象
?????*?@author?Tin
?????*
?????*/
????private?class?PageParameter?{
????????/**?*//**
?????????????*?參數名稱
?????????????*/
????????private?String?parameterName;
????????/**?*//**
?????????????*?參數值
?????????????*/
????????private?String?parameterValue;
????????/**?*//**
?????????????*?唯一構造函數
?????????????*?@param?parameterName?參數名稱
?????????????*?@param?parameterValue?參數值
?????????????*/
????????public?PageParameter(String?parameterName,?String?parameterValue)?{
????????????this.parameterName?=?parameterName;
????????????this.parameterValue?=?parameterValue;
????????}
????????public?String?getParameterName()?{
????????????return?parameterName;
????????}
????????public?String?getParameterValue()?{
????????????return?parameterValue;
????????}
????}
} ? 默認的分頁實現：
package?com.goldnet.framework.util.paging;
/**?*//**
?*?默認的分頁實現
?*?@author?Tin
?*
?*/
public?class?DefaultPagination?extends?AbstractPagination?{
????/**?*//**
????*?默認的構造函數
????*?@param?pageName?分頁的頁面的相對URL，不包括后綴
????*?@param?pageExtension?頁面的URL的后綴
????*?@param?itemSum?Page上顯示的List中的domainModel的總數
????*?@param?pageNo?頁數
????*?@param?pageSize?分頁的大小
?????*/
????public?DefaultPagination(String?pageName,?String?pageExtension,
????????int?itemSum,?int?pageNo,?int?pageSize)?{
????????super(pageName,?pageExtension,?itemSum,?pageNo,?pageSize);
????}
????/**?*//**
?????????*?無PageSize構造函數，使用默認PageSize為15
?????*?@param?pageName?分頁的頁面的相對URL，不包括后綴
?????*?@param?pageExtension?頁面的URL的后綴
?????*?@param?itemSum?Page上顯示的List中的domainModel的總數
?????*?@param?pageNo?頁數
?????????*/
????public?DefaultPagination(String?pageName,?String?pageExtension,
????????int?itemSum,?int?pageNo)?{
????????super(pageName,?pageExtension,?itemSum,?pageNo);
????}
????@Override
????public?void?compilePaginationString()?{
????????String?pageUrl?=?getPageUrl();
????????pageHtmlStr?=?"\u5171?"?+?itemSum?+?"?\u6761? \u7b2c?"?+
????????????(pageNo?+?1)?+?"?\u9875?/?\u5171?"?+?getPageSum()?+
????????????"?\u9875 ?<a?href=\""?+?pageUrl?+?"&"?+?PAGE_NO_KEY?+
????????????"=0\">\u9996\u9875</a> <a?href=\""?+?pageUrl?+?"&"?+
????????????PAGE_NO_KEY?+?"="?+?getPrevPageNo()?+
????????????"\">\u4e0a\u4e00\u9875</a>? <a?href=\""?+?pageUrl?+?"&"?+
????????????PAGE_NO_KEY?+?"="?+?getNextPageNo()?+
????????????"\">\u4e0b\u4e00\u9875</a>? <a?href=\""?+?pageUrl?+?"&"?+
????????????PAGE_NO_KEY?+?"="?+?(getPageSum()?-?1)?+
????????????"\">\u5c3e\u9875</a> \u6bcf\u9875\u663e\u793a"?+
????????????pageSize?+?"\u6761";
????}
}
數字風格的實現：
/**?*//**
?*
?*/
package?com.goldnet.framework.util.paging;
/**?*//**
?*?數字頁碼風格的分頁實現
?*?@author?Tin
?*
?*/
public?class?PageNumberPagination?extends?AbstractPagination?{
????/**?*//**
?????*?默認的構造函數
?????*?@param?pageName?分頁的頁面的相對URL，不包括后綴
?????*?@param?pageExtension?頁面的URL的后綴
?????*?@param?itemSum?Page上顯示的List中的domainModel的總數
?????*?@param?pageNo?頁數
?????*?@param?pageSize?分頁的大小
?????????*/
????public?PageNumberPagination(String?pageName,?String?pageExtension,
????????int?itemSum,?int?pageNo,?int?pageSize)?{
????????super(pageName,?pageExtension,?itemSum,?pageNo,?pageSize);
????}
????/**?*//**
?????*?無PageSize構造函數，使用默認PageSize為15
????*?@param?pageName?分頁的頁面的相對URL，不包括后綴
????*?@param?pageExtension?頁面的URL的后綴
????*?@param?itemSum?Page上顯示的List中的domainModel的總數
????*?@param?pageNo?頁數
?????*/
????public?PageNumberPagination(String?pageName,?String?pageExtension,
????????int?itemSum,?int?pageNo)?{
????????super(pageName,?pageExtension,?itemSum,?pageNo);
????}
????/**//*?(non-Javadoc)
?????*?@see?com.goldnet.framework.util.paging.AbstractPagination#compilePaginationString()
?????*/
????@Override
????public?void?compilePaginationString()?{
????????String?pageUrl?=?getPageUrl();
????????StringBuffer?returnString?=?new?StringBuffer();
????????returnString.append("\u5171?"?+?itemSum?+?"?\u6761? \u7b2c?"?+
????????????(pageNo?+?1)?+?"?\u9875?/?\u5171?"?+?getPageSum()?+
????????????"?\u9875 ?<a?href=\""?+?pageUrl?+?"&"?+?PAGE_NO_KEY?+?"="?+
????????????getPrevPageNo()?+?"\"><<</a> ");
????????for?(int?page?=?0;?page?<?getPageSum();?page++)?{
????????????if(page!=pageNo){
????????????????returnString.append("<a?href=\""+pageUrl?+"&"+PAGE_NO_KEY?+?"="?+?page?+"\">"+(page+1)+"</a> ");
????????????}?else?{
????????????????returnString.append("<a?href=\""+pageUrl?+"&"+PAGE_NO_KEY?+?"="?+?page?+"\"><span?style=\"background:black;color:#eee;font-size:120%;padding-left:5px;padding-right:5px;text-align:center;\">"+(page+1)+"</span></a> ");
????????????}
????????}
????????returnString.append(" <a?href=\""?+?pageUrl?+?"&"?+
????????????PAGE_NO_KEY?+?"="?+?getNextPageNo()?+
????????????"\">>></a>? \u6bcf\u9875\u663e\u793a"?+?pageSize?+
????????????"\u6761");
????????pageHtmlStr?=?returnString.toString();
????}
}
測試類，用的JUnit3，其實JUnit4更優雅:D
package?com.goldnet.test.unittest.framework.paging;
import?junit.framework.TestCase;
import?org.apache.commons.logging.Log;
import?org.apache.commons.logging.LogFactory;
import?com.goldnet.framework.util.paging.DefaultPagination;
import?com.goldnet.framework.util.paging.IPagination;
import?com.goldnet.framework.util.paging.PageNumberPagination;
public?class?TestPagination?extends?TestCase?{
????protected?transient?final?Log?log?=?LogFactory.getLog(getClass());
????protected?void?setUp()?throws?Exception?{
????????super.setUp();
????}
????protected?void?tearDown()?throws?Exception?{
????????super.tearDown();
????}
????public?void?testDefaultPainationWith3Parameters()?{
????????IPagination?p?=?new?DefaultPagination("test",".action",50,2);
????????p.addPageParameter("a","b");
????????p.addPageParameter("c","234");
????????p.addPageParameter("e.ddd","34234adbb");
????????log.info(p.getPageHtmlStr());
????}
????
????public?void?testDefaultPainationWith1Parameters()?{
????????IPagination?p?=?new?DefaultPagination("test",".action",50,2);
????????p.addPageParameter("a","b");
????????log.info(p.getPageHtmlStr());
????}
????
????public?void?testDefaultPainationWithNoParameters()?{
????????IPagination?p?=?new?DefaultPagination("test",".action",50,2);
????????log.info(p.getPageHtmlStr());
????}
????
????public?void?testDefaultPainationWith3ParametersAndCustomPageSize()?{
????????IPagination?p?=?new?DefaultPagination("test",".action",50,2,5);
????????p.addPageParameter("a","b");
????????p.addPageParameter("c","234");
????????p.addPageParameter("e.ddd","34234adbb");
????????log.info(p.getPageHtmlStr());
????}
????
????public?void?testDefaultPainationWithNoParametersAndCustomPageSize()?{
????????IPagination?p?=?new?DefaultPagination("test",".action",50,2,5);
????????log.info(p.getPageHtmlStr());
????}
????
????public?void?testPageNumberPainationWith3Parameters()?{
????????IPagination?p?=?new?PageNumberPagination("test",".action",50,2);
????????p.addPageParameter("a","b");
????????p.addPageParameter("c","234");
????????p.addPageParameter("e.ddd","34234adbb");
????????log.info(p.getPageHtmlStr());
????}
????
????public?void?testPageNumberPainationWith1Parameters()?{
????????IPagination?p?=?new?PageNumberPagination("test",".action",50,2);
????????p.addPageParameter("a","b");
????????log.info(p.getPageHtmlStr());
????}
????
????public?void?testPageNumberPainationWithNoParameters()?{
????????IPagination?p?=?new?PageNumberPagination("test",".action",50,2);
????????log.info(p.getPageHtmlStr());
????}
????
????public?void?testPageNumberPainationWith3ParametersAndCustomPageSize()?{
????????IPagination?p?=?new?PageNumberPagination("test",".action",50,2,5);
????????p.addPageParameter("a","b");
????????p.addPageParameter("c","234");
????????p.addPageParameter("e.ddd","34234adbb");
????????log.info(p.getPageHtmlStr());
????}
????
????public?void?testPageNumberPainationWithNoParametersAndCustomPageSize()?{
????????IPagination?p?=?new?PageNumberPagination("test",".action",50,2,5);
????????log.info(p.getPageHtmlStr());
????}
}
說實話這么丑陋的東西本不愿意現眼……但是實在沒什么可發的，應朋友所托共享出來。
特點就是分頁邏輯不管你用hibernate、JDBC、iBatis或者什么其他的，都可以和它一起工作，因為我任為對于DAO或者Action來說分頁邏輯就應該是pageSize、Pageno、itemSum這幾個參數的傳遞，具體的顯示上的問題應該交給第三方來負責，如taglib什么的，所以才寫了這樣的實現。而且這個實現應該容易擴展。配合js跳轉（css也應該抽出）等可以實現更多風格:D