更新時間:2021-09-06 10:58:10 來源:動力節點 瀏覽1125次
最終效果:
實現:
分頁查詢有幾個比較重要的參數,pageNum當前的頁數,pageSize每頁所展示的數據,totalRecord總共有多少數據,其他的數據可以根據這三個數據得出,有了這幾個數據就可以分頁查詢了
public class Page {
//當前的頁數
private int pageNum;
//每頁所展示的數據
private int pageSize;
//總共有多少數據
private int totalRecord;
//總頁數
private int totalPage;
//查詢數據的起始位置
private int startIndex;
//存放查詢到的數據
private List<Book> booklist;
//相對的頭頁
private int start;
//相對的尾頁
private int end;
public Page(int pageNum, int pageSize, int totalRecord) {
this.pageNum = pageNum;
this.pageSize = pageSize;
this.totalRecord = totalRecord;
if(totalRecord%pageSize == 0){
//如果剛好能夠整除,則totalPage = totalRecord/pageSize
this.totalPage = totalRecord/pageSize;
}else{
//如歌不能整除,則需要多加一頁顯示余下的數據
this.totalPage = (totalRecord/pageSize)+1;
}
this.startIndex = (pageNum-1)*pageSize;
//初始頭頁
this.start = 1;
//初始尾頁
this.end = 5;
if(totalPage<5){
//如果總頁數小于5頁,則尾頁為總頁數
this.end = this.totalPage;
}else{
this.start = this.pageNum-2;
this.end = this.pageNum+2;
if(this.start<0){
this.start = 1;
this.end = 5;
}
if(this.end>totalPage){
this.end = totalPage;
this.start = this.end-5;
}
}
}
//下面的為get/set方法
public int getPageNum() {
return pageNum;
}
public void setPageNum(int pageNum) {
this.pageNum = pageNum;
}
public int getPageSize() {
return pageSize;
}
public void setPageSize(int pageSize) {
this.pageSize = pageSize;
}
public int getTotalRecord() {
return totalRecord;
}
public void setTotalRecord(int totalRecord) {
this.totalRecord = totalRecord;
}
public int getTotalPage() {
return totalPage;
}
public void setTotalPage(int totalPage) {
this.totalPage = totalPage;
}
public int getStartIndex() {
return startIndex;
}
public void setStartIndex(int startIndex) {
this.startIndex = startIndex;
}
public List<Book> getBooklist() {
return booklist;
}
public void setBooklist(List<Book> booklist) {
this.booklist = booklist;
}
public int getStart() {
return start;
}
public void setStart(int start) {
this.start = start;
}
public int getEnd() {
return end;
}
public void setEnd(int end) {
this.end = end;
}
}
pageNum從請求中獲得,pageSize自己設置,totalRecord通過mybatis查詢獲得,一開始登錄的時候請求中沒有pageNum,所以進行一個判斷,如果沒有pageNum則賦值為1
//pageNum
String pageNum = request.getParameter("pageNum") == null?"1":request.getParameter("pageNum");
//pageSize
int pageSize = 7;
//totalRecord
int totalRecord = bookMapper.BookSize();
//mybatis
<select id="BookSize" resultType="int">
select count(*) from book
</select>
有了pageNum和startIndex就可以查詢到特定范圍的數據,通過使用mysql中的limit函數,limit有兩個參數,第一個參數為起始位置,即從那開始查,第二個參數為查詢范圍,即查多少個,如 limit 14,7 為從第14個數據開始往后查七個。
<select id="Books" parameterType="java.util.Map" resultType="book">
select *from book limit #{startIndex},#{pageSize}
</select>
public static Page getPageUser(int pageNum,int pageSize){
SqlSession sqlSession = GetSqlSession.getSqlSession();
BookMapper bookMapper = sqlSession.getMapper(BookMapper.class);
int totalRecord = bookMapper.BookSize();
Page page = new Page(pageNum,pageSize ,totalRecord );
int startIndex = page.getStartIndex();
Map<String,Integer> map = new HashMap<>();
map.put("startIndex",startIndex );
map.put("pageSize",pageSize );
page.setBooklist(bookMapper.Books(map));
return page;
}
jsp頁面:
<a href="index?pageNum=1">首頁</a>
<%--當前頁數為第一頁--%>
<c:if test="${sessionScope.page.pageNum == 1}">
<c:forEach begin="${sessionScope.page.start}" end="${sessionScope.page.end}" step="1" var="i">
<c:if test="${sessionScope.page.pageNum == i}">
<span style="color: deeppink">${i}</span>
</c:if>
<c:if test="${sessionScope.page.pageNum != i}">
<a href="index?pageNum=${i}">${i}</a>
</c:if>
</c:forEach>
<a href="index?pageNum=${sessionScope.page.pageNum+1}">下一頁</a>
</c:if>
<%--當前頁數為中間頁數--%>
<c:if test="${sessionScope.page.pageNum >1 && sessionScope.page.pageNum<sessionScope.page.totalPage}">
<a href="index?pageNum=${sessionScope.page.pageNum-1}">上一頁</a>
<c:forEach begin="${sessionScope.page.start}" end="${sessionScope.page.end}" step="1" var="i">
<c:if test="${sessionScope.page.pageNum == i}">
<span style="color: deeppink">${i}</span>
</c:if>
<c:if test="${sessionScope.page.pageNum != i}">
<a href="index?pageNum=${i}">${i}</a>
</c:if>
</c:forEach>
<a href="index?pageNum=${sessionScope.page.pageNum+1}">下一頁</a>
</c:if>
<%--當前頁數為最后一頁--%>
<c:if test="${sessionScope.page.pageNum == sessionScope.page.totalPage}">
<a href="index?pageNum=${sessionScope.page.pageNum-1}">上一頁</a>
<c:forEach begin="${sessionScope.page.start}" end="${sessionScope.page.end}" step="1" var="i">
<c:if test="${sessionScope.page.pageNum == i}">
<span style="color: deeppink">${i}</span>
</c:if>
<c:if test="${sessionScope.page.pageNum != i}">
<a href="index?pageNum=${i}">${i}</a>
</c:if>
</c:forEach>
</c:if>
<a href="index?pageNum=${sessionScope.page.totalPage}">尾頁</a>
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