說(shuō)到分頁(yè)算法,一般WEB開發(fā)都會(huì)用到,我只是在我的實(shí)現(xiàn)技術(shù)上用了struts框架,其實(shí)原理都一樣的。
看了網(wǎng)上相當(dāng)多的分頁(yè)算法,有對(duì)的也有好多是錯(cuò)的,更有好多是不太優(yōu)化的。還有以前自己在augmentum做的一個(gè)分頁(yè)算法,總結(jié)了一些不足。決定重新再寫一個(gè)分頁(yè)算法。
首先,應(yīng)該寫個(gè)bean來(lái)記錄存儲(chǔ)一些頁(yè)面的屬性
分頁(yè)大致需要如下屬性:
PRivate int currentPage = 1; // 當(dāng)前頁(yè)
private int totalPages = 0; // 總頁(yè)數(shù)
private int pageRecorders = 5;// 每頁(yè)5條數(shù)據(jù)
private int totalRows = 0; // 總數(shù)據(jù)數(shù)
private int pageStartRow = 0;// 每頁(yè)的起始數(shù)
private int pageEndRow = 0; // 每頁(yè)顯示數(shù)據(jù)的終止數(shù)
private boolean hasNextPage = false; // 是否有下一頁(yè)
private boolean haspreviousPage = false; // 是否有前一頁(yè)
private int nextPage = 0;//下一頁(yè)的頁(yè)碼
private int previousPage = 0;//上一頁(yè)的頁(yè)碼
然后這些屬性之間是有聯(lián)系的,我們可以在構(gòu)造函數(shù)的時(shí)候就初始化一些屬性
有兩種方法:
一,根據(jù)總的頁(yè)數(shù),(假設(shè)當(dāng)前頁(yè)為1)
public PageBean(int totalRows){
this.totalRows = totalRows;
this.currentPage = 1;
hasPreviousPage = false;
if ((totalRows % pageRecorders) == 0) {
totalPages = totalRows / pageRecorders;
} else {
totalPages = totalRows / pageRecorders + 1;
}
if (totalRows >= pageRecorders) {
hasNextPage = true;
nextPage = 2;
this.pageEndRow = pageRecorders;
} else {
this.pageEndRow = totalRows;
hasNextPage = false;
nextPage = 1;
}
this.pageStartRow = 0;
previousPage = 1;
}
然后在按下一頁(yè)或者上一頁(yè)的時(shí)候需要如下函數(shù)處理:
public void nextPage() {
if(hasNextPage == true)
currentPage = currentPage + 1;
if ((currentPage - 1) > 0) {
hasPreviousPage = true;
} else {
hasPreviousPage = false;
}
if (currentPage >= totalPages) {
hasNextPage = false;
this.nextPage = currentPage;
} else {
hasNextPage = true;
nextPage = currentPage+1;
}
this.pageStartRow = (currentPage -1) * pageRecorders;
if(hasNextPage == true)
this.pageEndRow = pageStartRow + 5;
else{
this.pageEndRow =this.totalPages;
}
previousPage = currentPage - 1;
}
public void previousPage() {
if(hasPreviousPage == true)
currentPage = currentPage - 1;
if (currentPage == 0) {
currentPage = 1;
}
if (currentPage >= totalPages) {
hasNextPage = false;
} else {
hasNextPage = true;
}
nextPage = currentPage + 1;
if ((currentPage - 1) > 0) {
hasPreviousPage = true;
previousPage = currentPage - 1;
} else {
hasPreviousPage = false;
previousPage = currentPage;
}
this.pageStartRow = (currentPage -1) * pageRecorders;
if(hasNextPage == true)
this.pageEndRow = pageStartRow + 5;
else{
this.pageEndRow =this.totalPages;
}
}
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