分页和多条件查询功能

转载自：http://m.blog.csdn.net/blog/ankeyuan/38376351

/** * 辅助拼接HQL语句的工具类 * @author G-Xia * */public class QueryHelper {private String fromClause; // From子句private String whereClause = ""; // Where子句private String orderByClause = ""; // OrderBy子句private List<Object> parameters = new ArrayList<Object>(); // 参数列表/** * 生成From子句 *  * @param clazz * @param alias *            别名 */public QueryHelper(Class clazz, String alias) {fromClause = "FROM " + clazz.getSimpleName() + " " + alias;}/** * 拼接Where子句 *  * @param condition * @param args */public QueryHelper addWhereCondition(String condition, Object... args) {// 拼接if (whereClause.length() == 0) {whereClause = " WHERE " + condition;} else {whereClause += " AND " + condition;}// 处理参数if (args != null && args.length > 0) {for (Object arg : args) {parameters.add(arg);}}return this;}/** * 如果第一个参数的值为true，就拼接Where子句 *  * @param append * @param condition * @param args */public QueryHelper addWhereCondition(boolean append, String condition, Object... args) {if (append) {addWhereCondition(condition, args);}return this;}/** * 拼接OrderBy子句 *  * @param propertyName * @param asc *            true表示升序，false表示降序 */public QueryHelper addOrderByProperty(String propertyName, boolean asc) {if (orderByClause.length() == 0) {orderByClause = " ORDER BY " + propertyName + (asc ? " ASC" : " DESC");} else {orderByClause += ", " + propertyName + (asc ? " ASC" : " DESC");}return this;}/** * 如果第一个参数的值为true，就拼接OrderBy子句 *  * @param append * @param propertyName * @param asc */public QueryHelper addOrderByProperty(boolean append, String propertyName, boolean asc) {if (append) {addOrderByProperty(propertyName, asc);}return this;}/** * 获取查询数据列表的HQL语句 *  * @return */public String getQueryListHql() {return fromClause + whereClause + orderByClause;}/** * 获取查询总记录数的HQL语句（没有OrderBy子句） *  * @return */public String getQueryCountHql() {return "SELECT COUNT(*) " + fromClause + whereClause;}/** * 获取参数列表 *  * @return */public List<Object> getParameters() {return parameters;}/** * 准备PageBean对象到Struts2的栈顶 * @param service * @param pageNum */public void preparePageBean(DaoSupport<?> service, int pageNum){PageBean pageBean = service.getPageBean(pageNum, this);ActionContext.getContext().getValueStack().push(pageBean);}}

PageBean：分页用的页面信息

public class PageBean {// 传递的参数或配置的值private int currentPage; // 当前页private int pageSize; // 每页显示的记录数// 查询数据库private int recordCount; // 总记录数private List recordList; // 本页的数据列表// 计算出来的private int pageCount; // 总页数private int beginPageIndex; // 页面列表的开始索引private int endPageIndex; // 页面列表的结束索引/** * 只接受前4个必要的属性的值，会自动的计算出后3个属性的值 *  * @param currentPage * @param pageSize * @param recordCount * @param recordList */public PageBean(int currentPage, int pageSize, int recordCount, List recordList) {this.currentPage = currentPage;this.pageSize = pageSize;this.recordCount = recordCount;this.recordList = recordList;// 计算pageCountpageCount = (recordCount + pageSize - 1) / pageSize;// 计算begPageIndex和endPageIndex// a, 总页数不超过10页，就全部显示if (pageCount <= 10) {beginPageIndex = 1;endPageIndex = pageCount;}// b, 总页数超过了10页，就显示当前页附近的共10个页码（前4个 + 当前页 + 后5个）else {// 显示当前页附近的共10个页码（前4个 + 当前页 + 后5个）beginPageIndex = currentPage - 4; // 7 - 4 = 3endPageIndex = currentPage + 5; // 7 + 5 = 12// 当前面不足4个页码时，就显示前10页if (beginPageIndex < 1) {beginPageIndex = 1;endPageIndex = 10;}// 当后面不足5个页码时，就显示后10页else if (endPageIndex > pageCount) {endPageIndex = pageCount;beginPageIndex = pageCount - 10 + 1; // 注意在显示的时候是包含两个边界的}}}public int getCurrentPage() {return currentPage;}public void setCurrentPage(int currentPage) {this.currentPage = currentPage;}public int getPageCount() {return pageCount;}public void setPageCount(int pageCount) {this.pageCount = pageCount;}public int getPageSize() {return pageSize;}public void setPageSize(int pageSize) {this.pageSize = pageSize;}public int getRecordCount() {return recordCount;}public void setRecordCount(int recordCount) {this.recordCount = recordCount;}public List getRecordList() {return recordList;}public void setRecordList(List recordList) {this.recordList = recordList;}public int getBeginPageIndex() {return beginPageIndex;}public void setBeginPageIndex(int beginPageIndex) {this.beginPageIndex = beginPageIndex;}public int getEndPageIndex() {return endPageIndex;}public void setEndPageIndex(int endPageIndex) {this.endPageIndex = endPageIndex;}}

/** * 公共的查询分页信息的方法（最终版） *  * @param pageNum * @param queryHelper *            查询语句 + 参数列表 * @return */public PageBean getPageBean(int pageNum, QueryHelper queryHelper) {System.out.println("------------> DaoSupportImpl.getPageBean( int pageNum, QueryHelper queryHelper )");// 获取pageSize等信息int pageSize = Configuration.getPageSize();List<Object> parameters = queryHelper.getParameters();// 查询一页的数据列表Query query = getSession().createQuery(queryHelper.getQueryListHql());if (parameters != null && parameters.size() > 0) { // 设置参数for (int i = 0; i < parameters.size(); i++) {query.setParameter(i, parameters.get(i));}}query.setFirstResult((pageNum - 1) * pageSize);query.setMaxResults(pageSize);List list = query.list(); // 查询// 查询总记录数query = getSession().createQuery(queryHelper.getQueryCountHql()); // 注意空格！if (parameters != null && parameters.size() > 0) { // 设置参数for (int i = 0; i < parameters.size(); i++) {query.setParameter(i, parameters.get(i));}}Long count = (Long) query.uniqueResult(); // 查询return new PageBean(pageNum, pageSize, count.intValue(), list);}

// 准备分页的数据 -- 使用QueryHelpernew QueryHelper(Topic.class, "t")//.addWhereCondition("t.forum=?", forum)//.addWhereCondition((viewType == 1), "t.type=?", Topic.TYPE_BEST) // 1 表示只看精华帖.addOrderByProperty((orderBy == 1), "t.lastUpdateTime", asc) // 1 表示只按最后更新时间排序.addOrderByProperty((orderBy == 2), "t.postTime", asc) // 表示只按主题发表时间排序.addOrderByProperty((orderBy == 3), "t.replyCount", asc) // 表示只按回复数量排序.addOrderByProperty((orderBy == 0), "(CASE t.type WHEN 2 THEN 2 ELSE 0 END)", false)//.addOrderByProperty((orderBy == 0), "t.lastUpdateTime", false) // 0 表示默认排序(所有置顶帖在前面，并按最后更新时间降序排列).preparePageBean(topicService, pageNum);

JSP中页面信息

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%@ taglib prefix="s" uri="/struts-tags" %><%-- 分页信息 --%><div id=PageSelectorBar><div id=PageSelectorMemo>页次：${currentPage}/${pageCount }页  每页显示：${pageSize }条  总记录数：${recordCount }条</div><div id=PageSelectorSelectorArea><a href="javascript: gotoPage(1)" title="首页" style="cursor: hand;"><img src="${pageContext.request.contextPath}/style/blue/images/pageSelector/firstPage.png"/></a><%-- 页码列表 --%><s:iterator begin="%{beginPageIndex}" end="%{endPageIndex}" var="num"><s:if test=" #num != currentPage "><%-- 非当前页，有链接 --%><span class="PageSelectorNum" style="cursor: hand;" onClick="gotoPage(${num});">${num}</span></s:if><s:else><%-- 当前页，没有链接 --%><span class="PageSelectorNum PageSelectorSelected">${num}</span></s:else></s:iterator><a href="javascript: gotoPage(${pageCount})" title="尾页" style="cursor: hand;"><img src="${pageContext.request.contextPath}/style/blue/images/pageSelector/lastPage.png"/></a>转到：<select id="pn" onchange="gotoPage( this.value )"><s:iterator begin="1" end="%{pageCount}" var="num"><option value="${num}">${num}</option></s:iterator></select><%-- 让select默认选中当前页 --%><script type="text/javascript">$("#pn").val( "${currentPage}" );</script></div></div><script type="text/javascript">/** * 转到指定的页码 * @param {Object} pageNum */function gotoPage( pageNum ){// 方式一： // window.location.href = "forum_show.do?id=${id}&pageNum=" + pageNum;// alert("请实现gotoPage()方法！");// 方式二：$("#pageForm").append("<input type='hidden' name='pageNum' value='" + pageNum + "'>"); // 添加pageNum表单字段$("#pageForm").submit(); // 提交表单}</script>