最近在做一個網上書店的項目,其中有一個功能就是對於查到的書籍進行分頁顯示,前面單獨學習分頁時沒有學好,導致不怎麼會做,所以搜到了CSDN上一位大神的博客直接拿過來套用了,因爲後面可能還會用到,所以現在這裏記錄下來,後面再去理解。
這是參考博客的地址
我這裏是根據書籍類型編號查找所有書籍,然後再進行分頁。所以需要準備的的參數是typeId。
1、首先新建一個工具包,創建一個Page類,類裏面的內容全部都是複製過來的。Page類如下:
package com.meet.tool;
import java.io.Serializable;
/**
* 分頁
*/
public class Page implements Serializable {
private static final long serialVersionUID = -3198048449643774660L;
private int pageNow = 1; // 當前頁數
private int pageSize = 4; // 每頁顯示記錄的條數
private int totalCount; // 總的記錄條數
private int totalPageCount; // 總的頁數
@SuppressWarnings("unused")
private int startPos; // 開始位置,從0開始
@SuppressWarnings("unused")
private boolean hasFirst;// 是否有首頁
@SuppressWarnings("unused")
private boolean hasPre;// 是否有前一頁
@SuppressWarnings("unused")
private boolean hasNext;// 是否有下一頁
@SuppressWarnings("unused")
private boolean hasLast;// 是否有最後一頁
/**
* 通過構造函數 傳入 總記錄數 和 當前頁
* @param totalCount
* @param pageNow
*/
public Page(int totalCount, int pageNow) {
this.totalCount = totalCount;
this.pageNow = pageNow;
}
/**
* 取得總頁數,總頁數=總記錄數/總頁數
* @return
*/
public int getTotalPageCount() {
totalPageCount = getTotalCount() / getPageSize();
return (totalCount % pageSize == 0) ? totalPageCount
: totalPageCount + 1;
}
public void setTotalPageCount(int totalPageCount) {
this.totalPageCount = totalPageCount;
}
public int getPageNow() {
return pageNow;
}
public void setPageNow(int pageNow) {
this.pageNow = pageNow;
}
public int getPageSize() {
return pageSize;
}
public void setPageSize(int pageSize) {
this.pageSize = pageSize;
}
public int getTotalCount() {
return totalCount;
}
public void setTotalCount(int totalCount) {
this.totalCount = totalCount;
}
/**
* 取得選擇記錄的初始位置
* @return
*/
public int getStartPos() {
return (pageNow - 1) * pageSize;
}
public void setStartPos(int startPos) {
this.startPos = startPos;
}
/**
* 是否是第一頁
* @return
*/
public boolean isHasFirst() {
return (pageNow == 1) ? false : true;
}
public void setHasFirst(boolean hasFirst) {
this.hasFirst = hasFirst;
}
/**
* 是否有首頁
* @return
*/
public boolean isHasPre() {
// 如果有首頁就有前一頁,因爲有首頁就不是第一頁
return isHasFirst() ? true : false;
}
public void setHasPre(boolean hasPre) {
this.hasPre = hasPre;
}
/**
* 是否有下一頁
* @return
*/
public boolean isHasNext() {
// 如果有尾頁就有下一頁,因爲有尾頁表明不是最後一頁
return isHasLast() ? true : false;
}
public void setHasNext(boolean hasNext) {
this.hasNext = hasNext;
}
/**
* 是否有尾頁
* @return
*/
public boolean isHasLast() {
// 如果不是最後一頁就有尾頁
return (pageNow == getTotalCount()) ? false : true;
}
public void setHasLast(boolean hasLast) {
this.hasLast = hasLast;
} }
2、在dao層的接口裏定義兩個方法,如下:
/*根據typeID分頁查找書籍*/
List<Book> selectBookByPage(@Param(value="startPos") int startPos,@Param(value="pageSize")int pageSize,@Param(value="typeId")int typeId);
/*計算要顯示書籍的總數量*/
long getBookCount(@Param(value="typeId")int typeId);`
3、在配置文件寫SQL語句,分別查找總數和書籍:
<!-- 根據typeID分頁查找書籍 -->
<select id="selectBookByPage" resultMap="PublishResultMap">
select book_id, title, summary, content, price, type_id, author, sellcount, count, imgurl,
b.publish_id, discount, isbn,publishname
from book b,publish p
where b.publish_id=p.publish_id and type_id = #{typeId,jdbcType=INTEGER}
limit #{startPos},#{pageSize}
</select>
<!-- 計算要顯示書籍的總數量 -->
<select id="getBookCount" resultType="long">
select count(*)
from book b,publish p
where b.publish_id=p.publish_id and type_id = #{typeId,jdbcType=INTEGER}
</select>
4、Services層處理業務邏輯:
/*根據typeID分頁查找書籍*/
public void selectBookByPage(HttpServletRequest request,Model model,int typeId){
String pageNow=request.getParameter("pageNow");
Page page=null;
List<Book> classlist=new ArrayList<Book>();
int totalCount=(int) bookMapper.getBookCount(typeId);
if (pageNow!=null) {
page=new Page(totalCount, Integer.parseInt(pageNow));
classlist=bookMapper.selectBookByPage(page.getStartPos(), page.getPageSize(), typeId);
}else {
page=new Page(totalCount, 1);
classlist=bookMapper.selectBookByPage(page.getStartPos(), page.getPageSize(), typeId);
}
model.addAttribute("classlist", classlist);
model.addAttribute("page", page);
}
5、controller層接收頁面傳遞過來的數據:
/*根據typeID分頁查找書籍*/
@RequestMapping("/selectBookByPage")
public String selectBookByPage(@Param("typeId") int typeId,HttpServletRequest request,Model model){
classifyServices.selectBookByPage(request, model, typeId);
return "classify.jsp";
}
5.最後就是頁面分頁的代碼,注意跳轉的時候把typeId傳進去,不然會報錯:
<div align="center">
<font size="2">共 ${page.totalPageCount} 頁</font> <font size="2">第
${page.pageNow}/ ${page.totalPageCount} 頁</font> <a href="selectBookByPage?pageNow=1&typeId=1">首頁</a>
<c:choose>
<c:when test="${page.pageNow - 1 > 0}">
<a href="selectBookByPage?pageNow=${page.pageNow - 1}&typeId=1">上一頁</a>
</c:when>
<c:when test="${page.pageNow - 1 <= 0}">
<a href="selectBookByPage?pageNow=1&typeId=1">上一頁</a>
</c:when>
</c:choose>
<c:choose>
<c:when test="${page.totalPageCount==0}">
<a href="selectBookByPage?pageNow=${page.pageNow}&typeId=1">下一頁</a>
</c:when>
<c:when test="${page.pageNow + 1 < page.totalPageCount}">
<a href="selectBookByPage?pageNow=${page.pageNow + 1}&typeId=1">下一頁</a>
</c:when>
<c:when test="${page.pageNow + 1 >= page.totalPageCount}">
<a href="selectBookByPage?pageNow=${page.totalPageCount}&typeId=1">下一頁</a>
</c:when>
</c:choose>
<c:choose>
<c:when test="${page.totalPageCount==0}">
<a href="selectBookByPage?pageNow=${page.pageNow}&typeId=1">尾頁</a>
</c:when>
<c:otherwise>
<a href="selectBookByPage?pageNow=${page.totalPageCount}&typeId=1">尾頁</a>
</c:otherwise>
</c:choose>
</div>