目前较常用的分页实现办法有两种:

1.每次翻页都修改SQL,向SQL传入相关参数去数据库实时查出该页的数据并显示。

2.查出数据库某张表的全部数据,再通过在业务逻辑里面进行处理去取得某些数据并显示。

对于数据量并不大的简单的管理系统而言,第一种实现方法相对来说容易使用较少的代码实现分页这一功能,本文也正是为大家介绍这种方法:

代码片段:

1,Page.java

package com.cm.contract.common; 
  
import org.apache.commons.lang.StringUtils; 
import org.apache.commons.lang.builder.ToStringBuilder; 
  
  
  
/**分页类 
 * @author FENGWEI 
 * @date 2016-5-23 
 */
public class Page implements java.io.Serializable{ 
    
  private static final long serialVersionUID = 1L; 
  //前一页 
  private Boolean hasPrePage; 
  //后一页 
  private Boolean hasNextPage; 
  //每页显示多少条:默认20条 
  private Long everyPage = 20L; 
  //总页数 
  private Long totalPage; 
  //当前第多少页:默认第1页 
  private Long currentPage = 1L; 
  //开始下标 
  private Long beginIndex; 
  //结束下标 
  private Long endinIndex; 
  //总共多少条 
  private Long totalCount;   
  //排序列名 
  private String sortName;   
  //排序状态 
  private String sortState;   
  //排序信息 
  private String sortInfo; 
  //是否排序 
  private Boolean sort = false; 
  private String defaultInfo = " "; 
    
    
    
  public String getDefaultInfo() { 
    return defaultInfo; 
  } 
  
  public void setDefaultInfo(String defaultInfo) { 
    this.defaultInfo = defaultInfo; 
  } 
  
  public String getSortInfo() { 
    return sortInfo; 
  } 
  
  public void setSortInfo(String sortInfo) { 
    this.sortInfo = sortInfo; 
  } 
  
  public String getSortName() { 
    return sortName; 
  } 
  
  public void setSortName(String sortName) { 
    setPageSortState(sortName);    
  } 
  
  public String getSortState() { 
    return sortState; 
  } 
  
  public void setSortState(String sortState) { 
    this.sortState = sortState; 
  } 
  
    
  public Page() { 
  } 
  
  /** 
   * 常用,用于计算分页 
   * */
  public Page(Long totalRecords){    
    this.totalCount = totalRecords; 
    setTotalPage(getTotalPage(totalRecords));    
  } 
    
  /** 
   * 设置每页显示多少条时使用 
   * */
  public Page(Long everyPage,Long totalRecords){  
    this.everyPage = everyPage; 
    this.totalCount = totalRecords; 
    setTotalPage(getTotalPage(totalRecords));    
  } 
    
  /** 
   * @param state  状态码 
   * @param value  到第多少页或者设置每页显示多少条或者为排序列名 
   */
  public void pageState(int index,String value) {         
    sort = false; 
    switch (index) { 
    case 0 :setEveryPage(Long.parseLong(value));break; 
    case 1 :first();break; 
    case 2: previous();break; 
    case 3: next();break; 
    case 4: last();break; 
    case 5: sort = true;sort(value);break; 
    case 6 ://到指定第多少页 
      setCurrentPage(Long.parseLong(value)); 
      break;      
    } 
  } 
  
  /** 
   * 最前一页 
   */
  private void first() { 
    currentPage = 1L; 
  } 
  
  private void previous() { 
    currentPage--; 
  } 
  
  private void next() { 
    currentPage++; 
  } 
  
  private void last() { 
    currentPage = totalPage; 
  } 
  
  private void sort(String sortName) {     
    //设置排序状态 
    setPageSortState(sortName);    
  } 
      
    
    
  /** 
   * 计算总页数 
   * */
  private Long getTotalPage(Long totalRecords) { 
     Long totalPage = 0L;   
     everyPage = everyPage == null ? 10L : everyPage; 
     if (totalRecords % everyPage == 0) 
      totalPage = totalRecords / everyPage; 
     else { 
      totalPage = totalRecords / everyPage + 1; 
     } 
     return totalPage; 
  }   
    
  
  public Long getBeginIndex() { 
    this.beginIndex = (currentPage - 1) * everyPage; 
    return this.beginIndex; 
  } 
  
  public void setBeginIndex(Long beginIndex) { 
    this.beginIndex = beginIndex; 
  } 
  
  public Long getCurrentPage() { 
    this.currentPage = currentPage == 0 ? 1 : currentPage; 
    return this.currentPage; 
  } 
  
  public void setCurrentPage(Long currentPage) { 
    if(0 == currentPage){ 
      currentPage = 1L; 
    } 
    this.currentPage = currentPage; 
  } 
  
  public Long getEveryPage() { 
    this.everyPage = everyPage == 0 ? 10 : everyPage; 
    return this.everyPage; 
  } 
  
  public void setEveryPage(Long everyPage) {    
    this.everyPage = everyPage; 
  } 
  
  public Boolean getHasNextPage() { 
    this.hasNextPage = (currentPage != totalPage) && (totalPage != 0); 
    return this.hasNextPage; 
  } 
  
  public void setHasNextPage(Boolean hasNextPage) { 
    this.hasNextPage = hasNextPage; 
  } 
  
  public Boolean getHasPrePage() { 
    this.hasPrePage = currentPage != 1; 
    return this.hasPrePage; 
  } 
  
  public void setHasPrePage(Boolean hasPrePage) { 
    this.hasPrePage = hasPrePage; 
  } 
  
  public Long getTotalPage() { 
    return this.totalPage; 
  } 
  
  public void setTotalPage(Long totalPage) { 
    if(this.currentPage > totalPage){ 
      this.currentPage = totalPage; 
    } 
    this.totalPage = totalPage; 
  } 
  
  public Long getTotalCount() { 
    return this.totalCount; 
  } 
  
  public void setTotalCount(Long totalCount) { 
    setTotalPage(getTotalPage(totalCount));  
    this.totalCount = totalCount; 
  } 
  
  @Override
  public String toString() { 
    return ToStringBuilder.reflectionToString(this); 
  } 
    
  /** 
   * 设置排序状态 
   * */
  private void setPageSortState(String newPageSortName){    
    //判断之前的排序字段是否为空 
    if(StringUtils.isEmpty(sortName)){ 
      //默认排序为升序 
      this.sortState = PageUtil.ASC;    
      this.sortInfo = PageUtil.PAGE_ASC;            
    }else{ 
      if(StringUtils.equalsIgnoreCase(newPageSortName, sortName)){ 
        //判断sortState排序状态值 
        if(StringUtils.equalsIgnoreCase(sortState, PageUtil.ASC)){ 
          this.sortState = PageUtil.DESC; 
          this.sortInfo = PageUtil.PAGE_DESC;                
        }else{ 
          this.sortState = PageUtil.ASC; 
          this.sortInfo = PageUtil.PAGE_ASC;          
        }         
      }else{ 
        //默认 
        this.sortState = PageUtil.ASC;    
        this.sortInfo = PageUtil.PAGE_ASC; 
      } 
    } 
    sortName = newPageSortName.toLowerCase();       
  } 
  
  public Boolean isSort() { 
    return sort; 
  } 
  
  public void setSort(Boolean sort) { 
    this.sort = sort; 
  } 
  
  
  public Long getEndinIndex() { 
    this.endinIndex = (currentPage) * everyPage; 
    return endinIndex; 
  } 
  
  public void setEndinIndex(Long endinIndex) { 
    this.endinIndex = endinIndex; 
  }   
}
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2.PageState.java

package com.cm.contract.common; 
  
import org.apache.commons.lang.StringUtils; 
  
  
  
  
/**分页状态类 
 * @author FENGWEI 
 * @date 2016-5-23 
 */
public enum PageState { 
    
  /** 
   * 设置每页显示多少条 
   * */
  SETPAGE, 
  /** 
   * 首页 
   * */
  FIRST,  
  /** 
   * 向前一页 
   * */
  PREVIOUS,  
  /** 
   * 向后一页 
   * */
  NEXT,  
  /** 
   * 末页 
   * */
  LAST,  
  /** 
   * 排序 
   * */
  SORT, 
  /** 
   * 到第多少页 
   * */
  GOPAGE; 
  
    
  /** 
   * @param value 索引名称 
   * @return 返回索引下标 
   */
  public static int getOrdinal(String value) { 
    int index = -1; 
    if (StringUtils.isEmpty(value)) { 
      return index; 
    } 
    String newValue = StringUtils.trim(value).toUpperCase(); 
    try { 
      index = valueOf(newValue).ordinal(); 
    } catch (IllegalArgumentException e) {} 
    return index; 
  } 
}
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3.PageUtil.java

/** 
 * 分页工具类 
 * @author FENGWEI 
 * @date 2016-5-23 
 */
public class PageUtil { 
    
  public static final String ASC = "asc"; 
  public static final String DESC = "desc"; 
  public static final String PAGE_DESC = "↓"; 
  public static final String PAGE_ASC = "↑"; 
  public static final String PAGE_NULL = " ";  
  public static final String SESSION_PAGE_KEY = "page";   
    
    
  /** 
   * 初始化分页类 
   * @param initPageSql 未分页的查询SQL 
   * @param totalCount  总行数 
   * @param index    分页状态 
   * @param value    只有在设置每页显示多少条时,值不会NULL,其它为NULL 
   */
  public static Page inintPage(Long totalCount,Integer index,String value,Page sessionPage){  
    Page page = null; 
    if(index < 0){ 
       page = new Page(totalCount); 
    }else{ 
       /**每页显示多少条*/
       Long everPage = null == value ? 10 : Long.parseLong(value); 
       /**获取Session中的分页类,方便保存页面分页状态*/
       page = sessionPage;        
       page.setEveryPage(everPage); 
       page.setTotalCount(totalCount);       
    }   
    return page;     
  } 
    
    
  
    
  /** 
   * 当页点击:首页,前一页,后一页,末页,排序,到第多少页时进行分页操作 
   * @param index 分页状态 
   * @param value 排序字段名或者到第多少页 
   */
  public static Page execPage(int index,String value,Page sessionPage){  
    Page page = sessionPage;       
    /**调用方法进行分页计算*/
    page.pageState(index,value);     
    return page;     
  } 
  
}
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4.DefaultController.java 此部分可以灵活使用

package com.cm.contract.common; 
  
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
import javax.servlet.http.HttpSession; 
  
import org.springframework.web.bind.annotation.ModelAttribute; 
  
/** 
 * 提取公用的request和response Title:DefaultController Descrption: 
 * 
 * @author FENGWEI 
 * @date 2016-5-6下午3:30:32 
 */
public class DefaultController { 
  
  /** 
   * oracel的三层分页语句 子类在展现数据前,进行分页计算! 
   * 
   * @param querySql 
   *      查询的SQL语句,未进行分页 
   * @param totalCount 
   *      根据查询SQL获取的总条数 
   * @param columnNameDescOrAsc 
   *      列名+排序方式 : ID DESC or ASC 
   */
  protected Page executePage(HttpServletRequest request, Long totalCount) { 
    if (null == totalCount) { 
      totalCount = 0L; 
    } 
    /** 页面状态,这个状态是分页自带的,与业务无关 */
    String pageAction = request.getParameter("pageAction"); 
    String value = request.getParameter("pageKey"); 
  
    /** 获取下标判断分页状态 */
    int index = PageState.getOrdinal(pageAction); 
  
    Page page = null; 
    /** 
     * index < 1 只有二种状态 1 当首次调用时,分页状态类中没有值为 NULL 返回 -1 2 当页面设置每页显示多少条: 
     * index=0,当每页显示多少条时,分页类要重新计算 
     * */
    Page sessionPage = getPage(request); 
  
    if (index < 1) { 
      page = PageUtil.inintPage(totalCount, index, value, sessionPage); 
    } else { 
      page = PageUtil.execPage(index, value, sessionPage); 
    } 
    setSession(request, page); 
    return page; 
  } 
  
  private Page getPage(HttpServletRequest request) { 
    Page page = (Page) request.getSession().getAttribute( 
        PageUtil.SESSION_PAGE_KEY); 
    if (page == null) { 
      page = new Page(); 
    } 
    return page; 
  } 
  
  private void setSession(HttpServletRequest request, Page page) { 
    request.getSession().setAttribute(PageUtil.SESSION_PAGE_KEY, page); 
  } 
}
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使用方法:

5,Controller.java

/** 
   * model 添加的分页条件 
   * executePage 方法写在工具类中 
   * @param model 
   */
@Controller
public class CMLogController extends DefaultController { 
@RequestMapping("index.do") 
  public ModelAndView userInto(ModelMap model, String username) { 
    nameStr = username; 
    model.addAttribute("username", nameStr); 
    // 分页数 
    Long totalCount = logService.pageCounts(model); 
    // 分页显示 
    Page page = executePage(request, totalCount); 
    if (page.isSort()) { 
      model.put("orderName", page.getSortName()); 
      model.put("descAsc", page.getSortState()); 
    } else { 
      model.put("orderName", "logtime"); 
      model.put("descAsc", "desc"); 
    } 
    model.put("startIndex", page.getBeginIndex()); 
    model.put("endIndex", page.getEndinIndex()); 
    ModelAndView mv = new ModelAndView(); 
    // 分页查询 
    logList = logService.pageList(model); 
    mv.addObject("logList", logList); 
    mv.setViewName("/jsp/log"); 
    return mv; 
  }}
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6.maybatis中几条查询语句

//分页查询 
<select id="pageList" parameterType="map" resultMap="BaseResultMap">   
      
    select ttt.* from(select tt.*,rownum rn from(select * from CM_LOG 
    <where>      
      <if test="username != null and username != ''"> 
        <!--  
         特别提醒一下, $只是字符串拼接, 所以要特别小心sql注入问题。 
         在开发时使用: $,方便调试sql,发布时使用: # 
        -->
        and username like '%${username}%'           
      </if> 
       <if test="type != null and type != ''"> 
        <!--  
         特别提醒一下, $只是字符串拼接, 所以要特别小心sql注入问题。 
         在开发时使用: $,方便调试sql,发布时使用: # 
        -->
        AND TYPE = #{type,jdbcType=VARCHAR}    
      </if> 
     </where>  
     order by ${orderName} ${descAsc} )tt)ttt 
     <where>  
      <if test="startIndex != null and startIndex != ''"> 
        rn > ${startIndex}           
      </if>  
      <if test="endIndex != null and endIndex != ''">        
         <![CDATA[ and rn <= ${endIndex} ]]>               
      </if>   
     </where>      
</select> 
// 分页数 
 <select id="pageCounts" parameterType="map" resultType="long">   
  select count(*) from CM_LOG  
  <where>  
  <if test="username != null and username != ''"> 
    and username like '%${username}%'          
  </if>  
  </where>  
</select>
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7.前台页面index.jsp

//只需在页面布局添加该div 
  //username 为条件  
  // <jsp:param name="url" value="/log/index.do?"/>    不带条件的方式 问号必须存在 
<body > 
  <div align="right" style="height: 20"> 
      <jsp:include page="/jsp/page.jsp"> 
          <jsp:param name="url" value="/log/index.do?username=${username }"/>     
  
        </jsp:include> 
    </div> 
  
    </body >
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8,引用的Page.jsp

  <%@ page language="java" contentType="text/html; charset=UTF-8"
  pageEncoding="UTF-8"%> 
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%> 
<c:set var="page" value="${sessionScope.page}" /> 
<c:set var="path" value="${pageContext.request.contextPath}" /> 
<c:set var="url" value="${param.url}" /> 
<c:set var="urlParams" value="${param.urlParams}" /> 
<c:set var="pathurl" value="${path}/${url}" /> 
<tr> 
  <td colspan="5"> 
  ${urlParams } 
    共${page.totalCount}条记录 共${page.totalPage}页 每页显示${page.everyPage}条 
    当前第${page.currentPage}页  
    <c:choose> 
      <c:when test="${page.hasPrePage eq false}"> 
        <<首页 <上页  
      </c:when> 
      <c:otherwise> 
        <a href="${pathurl}&pageAction=first${urlParams}"><<首页 </a>  
        <a href="${pathurl}&pageAction=previous${urlParams}" /><上一页</a> 
      </c:otherwise> 
    </c:choose> 
     ||  
    <c:choose> 
      <c:when test="${page.hasNextPage eq false}"> 
         下页> 尾页>> 
      </c:when> 
      <c:otherwise> 
        <a href="${pathurl}&pageAction=next${urlParams}">下一页> </a>  
        <a href="${pathurl}&pageAction=last${urlParams}">末页>></a> 
      </c:otherwise> 
    </c:choose> 
       
    <SELECT name="indexChange" id="indexChange"
      onchange="getCurrentPage(this.value);"> 
      <c:forEach var="index" begin="1" end="${page.totalPage}" step="1"> 
        <option value="${index}" ${page.currentPage eq index ? "selected" : ""}> 
          第${index}页 
        </option> 
      </c:forEach> 
    </SELECT> 
       
    每页显示:<select name="everyPage" id="everyPage" onchange="setEveryPage(this.value);"> 
          <c:forEach var="pageCount" begin="5" end="${page.totalCount}" step="5">             
            <option value="${pageCount}" ${page.everyPage eq pageCount ? "selected" : ""}> 
              ${pageCount}条 
            </option> 
          </c:forEach> 
        </select> 
  </td> 
</tr> 
<div style='display: none'> 
  <a class=listlink id="indexPageHref" href='#'></a> 
</div> 
<script> 
function getCurrentPage(index){  
  var a = document.getElementById("indexPageHref");   
  a.href = '${pathurl}&pageAction=gopage&pageKey='+index+'${urlParams}';     
  a.setAttribute("onclick",'');      
  a.click("return false");   
} 
function setEveryPage(everyPage){   
  var a = document.getElementById("indexPageHref"); 
  var currentPage = document.getElementById('indexChange').value; 
  a.href = '${pathurl}&pageAction=setpage&pageKey='+everyPage+'${urlParams}';     
  a.setAttribute("onclick",'');      
  a.click("return false");   
} 
function sortPage(sortName){   
  var a = document.getElementById("indexPageHref");   
  a.href = '${pathurl}&pageAction=sort&pageKey='+sortName+'${urlParams}';    
  a.setAttribute("onclick",'');    
  a.click("return false");   
} 
</script>
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以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持Work网。

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09-18 01:26