通過rs.next()進行分頁,首先用rs.absolute(0)定位到某條記錄。然后循環(huán)取數(shù)例如:1-10 可以for(int i=0;i10;i++){rs.next()}
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import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.Enumeration;
import javax.servlet.http.HttpServletRequest;
import com.lqh.dao.db.DBCon;
public class PageDAO {
public static final String Text = "text";
public static final String Image = "image";
public static final String BbsText = "bbstext";
public static final String BbsImage = "bbsimage";
private HttpServletRequest request;
private int currentpage = 1; // 當(dāng)前是第幾頁
private int pagecount = 0; // 一共有多少頁
private int rscount = 0; // 一共有多少行
private int pagesize = 10; // 每頁有多少行[默認(rèn)為20行]
public PageDAO(HttpServletRequest request) {
this.request = request;
}
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 getRscount() {
return rscount;
}
public void setRscount(int rscount) {
this.rscount = rscount;
}
/**
* 傳入SQL語句獲取總記錄數(shù)
*/
public int getRsCountForRs(String sql) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
DBCon dbcon=new DBCon();
try {
conn = dbcon.getConn();
ps = conn.prepareStatement(sql);
rs = ps.executeQuery();
if (rs.next()) {
rs.last();
this.rscount = rs.getRow();
} else {
this.rscount = 0;
}
} catch (Exception ex) {
ex.printStackTrace();
this.rscount = 0;
} finally {
dbcon.tryClose(rs, ps, conn);
}
return this.rscount;
}
public int getRsCountForSQL(String sql) {
Connection conn = null;
PreparedStatement ps = null;
ResultSet rs = null;
DBCon dbcon=new DBCon();
try {
conn = dbcon.getConn();
ps = conn.prepareStatement(sql);
rs = ps.executeQuery();
if (rs.next()) {
this.rscount = rs.getInt("rscount");
} else {
this.rscount = 0;
}
} catch (Exception ex) {
ex.printStackTrace();
this.rscount = 0;
} finally {
dbcon.tryClose(rs, ps, conn);
}
return this.rscount;
}
/**
* 獲取總頁數(shù)
*
* @return int
*/
public int getPageCount() {
try {
this.pagecount = ((this.rscount - 1) / this.pagesize) + 1;
} catch (Exception ex) {
this.pagecount = 0;
}
return this.pagecount;
}
/**
* 獲取當(dāng)前頁碼的設(shè)置
*
* @return int
*/
public int getCurrentPage() {
try {
if (this.request.getParameter("currentpage") != null
Integer.parseInt(this.request
.getParameter("currentpage")) 1) {
this.currentpage = Integer.parseInt(this.request
.getParameter("currentpage"));
} else {
this.currentpage = 1;
}
} catch (Exception ex) {
this.currentpage = 1;
}
return this.currentpage;
}
/**
* 分頁工具條
*
* @param fileName
* String
* @return String
*/
public String pagetool(String flag) {
StringBuffer str = new StringBuffer();
String url = this.getParamUrl();
int ProPage = this.currentpage - 1;
int Nextpage = this.currentpage + 1;
// 文字的分頁
if (flag.equals(PageDAO.Text)) {
str.append("form method='post' name='pageform' action=''");
str
.append("table style='color: windowframe' width='100%' border='0' cellspacing='0' cellpadding='0'");
str.append("tr");
str.append("td width='20%'/td");
str.append("td height='26'");
str.append("共有記錄" + this.rscount + "條?");
str.append("共" + this.pagecount + "頁?");
str.append("每頁" + this.pagesize + "記錄?");
str.append("現(xiàn)在" + this.currentpage + "/" + this.pagecount + "頁");
str.append("/tdtd");
if (this.currentpage 1) {
str.append("a href='" + url + "currentpage=1'首頁/a");
str.append("?");
str.append("a href='" + url + "currentpage=" + ProPage
+ "'上一頁/a");
str.append("?");
} else {
str.append("首頁");
str.append("?");
str.append("上一頁");
str.append("?");
}
if (this.currentpage this.pagecount) {
str.append("a href='" + url + "currentpage=" + Nextpage
+ "'下一頁/a");
str.append("?");
} else {
str.append("下一頁");
str.append("?");
}
if (this.pagecount 1 this.currentpage != this.pagecount) {
str.append("a href='" + url + "currentpage=" + pagecount
+ "'尾頁/a");
str.append("?");
} else {
str.append("尾頁");
str.append("?");
}
str.append("轉(zhuǎn)到");
str
.append("select name='currentpage' onchange='javascript:ChangePage(this.value);'");
for (int j = 1; j = pagecount; j++) {
str.append("option value='" + j + "'");
if (currentpage == j) {
str.append("selected");
}
str.append("");
str.append("" + j + "");
str.append("/option");
}
str.append("/select頁");
str.append("/tdtd width='3%'?/td/tr/table");
str.append("script language='javascript'");
str.append("function ChangePage(testpage){");
str.append("document.pageform.action='" + url
+ "currentpage='+testpage+'';");
str.append("document.pageform.submit();");
str.append("}");
str.append("/script");
str.append("/form");
} else if (flag.equals(PageDAO.Image)) {
/**
* 圖片的分頁
*/
} else if (flag.equals(PageDAO.BbsText)) {
/**
* 論壇形式的分頁[直接以數(shù)字方式體現(xiàn)]
*/
str
.append("table width='100%' border='0' cellspacing='0' cellpadding='0'");
str.append("tr");
str.append("td width='3%'?/td");
str.append("td height='26'");
str.append("記錄" + this.rscount + "條??");
str.append("共" + this.pagecount + "頁??");
str.append("每頁" + this.pagesize + "記錄??");
str.append("現(xiàn)在" + this.currentpage + "/" + this.pagecount + "頁");
str.append("/tdtd");
// 設(shè)定是否有首頁的鏈接
if (this.currentpage 1) {
str.append("a href='" + url + "currentpage=1'首頁/a");
str.append("??");
}
// 設(shè)定是否有上一頁的鏈接
if (this.currentpage 1) {
str.append("a href='" + url + "currentpage=" + ProPage
+ "'上一頁/a");
str.append("???");
}
// 如果總頁數(shù)只有10的話
if (this.pagecount = 10) {
for (int i = 1; i = this.pagecount; i++) {
if (this.currentpage == i) {
str.append("font color=red[" + i
+ "]/font??");
} else {
str.append("a href='" + url + "currentpage=" + i
+ "'" + i + "/a??");
}
}
} else {
// 說明總數(shù)有超過10頁
// 制定特環(huán)的開始頁和結(jié)束頁
int endPage = this.currentpage + 4;
if (endPage this.pagecount) {
endPage = this.pagecount;
}
int startPage = 0;
if (this.pagecount = 8 this.currentpage = 8) {
startPage = this.currentpage - 5;
} else {
// 表示從第一頁開始算
startPage = 1;
}
System.out.println(startPage);
System.out.println(endPage);
for (int i = startPage; i = endPage; i++) {
if (this.currentpage == i) {
str.append("font color=red[" + i
+ "]/font??");
} else {
str.append("a href='" + url + "currentpage=" + i
+ "'" + i + "/a??");
}
}
}
// 設(shè)定是否有下一頁的鏈接
if (this.currentpage this.pagecount) {
str.append("a href='" + url + "currentpage=" + Nextpage
+ "'下一頁/a");
str.append("??");
}
// 設(shè)定是否有尾頁的鏈接
if (this.pagecount 1 this.currentpage != this.pagecount) {
str.append("a href='" + url + "currentpage=" + pagecount
+ "'尾頁/a");
str.append("??");
}
str.append("/tdtd width='3%'?/td/tr/table");
} else if (flag.equals(PageDAO.BbsImage)) {
/**
* 論壇形式的分頁[以圖片的方式體現(xiàn)]
*/
// 設(shè)定分頁顯示的CSS
str.append("style");
str
.append("BODY {FONT-SIZE: 12px;FONT-FAMILY:宋體;WIDTH: 60%; PADDING-LEFT: 25px;}");
str
.append("DIV.meneame {PADDING-RIGHT: 3px; PADDING-LEFT: 3px; FONT-SIZE: 80%; PADDING-BOTTOM: 3px; MARGIN: 3px; COLOR: #ff6500; PADDING-TOP: 3px; TEXT-ALIGN: center}");
str
.append("DIV.meneame A {BORDER-RIGHT: #ff9600 1px solid; PADDING-RIGHT: 7px; BACKGROUND-POSITION: 50% bottom; BORDER-TOP: #ff9600 1px solid; PADDING-LEFT: 7px; BACKGROUND-IMAGE: url('"
+ this.request.getContextPath()
+ "/meneame.jpg'); PADDING-BOTTOM: 5px; BORDER-LEFT: #ff9600 1px solid; COLOR: #ff6500; MARGIN-RIGHT: 3px; PADDING-TOP: 5px; BORDER-BOTTOM: #ff9600 1px solid; TEXT-DECORATION: none}");
str
.append("DIV.meneame A:hover {BORDER-RIGHT: #ff9600 1px solid; BORDER-TOP: #ff9600 1px solid; BACKGROUND-IMAGE: none; BORDER-LEFT: #ff9600 1px solid; COLOR: #ff6500; BORDER-BOTTOM: #ff9600 1px solid; BACKGROUND-COLOR: #ffc794}");
str
.append("DIV.meneame SPAN.current {BORDER-RIGHT: #ff6500 1px solid; PADDING-RIGHT: 7px; BORDER-TOP: #ff6500 1px solid; PADDING-LEFT: 7px; FONT-WEIGHT: bold; PADDING-BOTTOM: 5px; BORDER-LEFT: #ff6500 1px solid; COLOR: #ff6500; MARGIN-RIGHT: 3px; PADDING-TOP: 5px; BORDER-BOTTOM: #ff6500 1px solid; BACKGROUND-COLOR: #ffbe94}");
str
.append("DIV.meneame SPAN.disabled {BORDER-RIGHT: #ffe3c6 1px solid; PADDING-RIGHT: 7px; BORDER-TOP: #ffe3c6 1px solid; PADDING-LEFT: 7px; PADDING-BOTTOM: 5px; BORDER-LEFT: #ffe3c6 1px solid; COLOR: #ffe3c6; MARGIN-RIGHT: 3px; PADDING-TOP: 5px; BORDER-BOTTOM: #ffe3c6 1px solid}");
str.append("/style");
str.append("div class=\"meneame\"");
// 判定是否有上一頁
if (this.currentpage 1) {
str.append("a href='" + url
+ "currentpage=1' hidefocus=\"true\"首頁/a");
str.append("???");
str.append("a href='" + url + "currentpage=" + ProPage
+ "' hidefocus=\"true\"上一頁/a");
str.append("???");
} else {
str.append("span class=\"disabled\"首頁/span");
str.append("??");
str.append("span class=\"disabled\"上一頁/span");
str.append("??");
}
// 顯示中間的圖片
if (this.pagecount = 10) {
for (int i = 1; i = this.pagecount; i++) {
if (this.currentpage == i) {
str.append("span class=\"current\"" + i + "/span");
} else {
str.append("a href='" + url + "currentpage=" + i
+ "' hidefocus=\"true\"" + i
+ "/a??");
}
}
} else {
// 說明總數(shù)有超過10頁
// 制定特環(huán)的開始頁和結(jié)束頁
int endPage = this.currentpage + 4;
if (endPage this.pagecount) {
endPage = this.pagecount;
}
int startPage = 0;
if (this.pagecount = 8 this.currentpage = 8) {
startPage = this.currentpage - 5;
} else {
// 表示從第一頁開始算
startPage = 1;
}
System.out.println(startPage);
System.out.println(endPage);
for (int i = startPage; i = endPage; i++) {
if (this.currentpage == i) {
str.append("span class=\"current\"" + i + "/span");
} else {
str.append("a href='" + url + "currentpage=" + i
+ "' hidefocus=\"true\"" + i
+ "/a??");
}
}
}
// 判斷下一頁和尾頁
if (this.currentpage this.pagecount) {
if (this.currentpage this.pagecount - 10) {
str.append("...");
str.append("a href='" + url + "currentpage="
+ (this.pagecount - 1) + "' hidefocus=\"true\""
+ (this.pagecount - 1) + "/a??");
str.append("a href='" + url + "currentpage="
+ this.pagecount + "' hidefocus=\"true\""
+ this.pagecount + "/a??");
}
str.append("a href='" + url + "currentpage=" + Nextpage
+ "' hidefocus=\"true\"下一頁/a");
str.append("??");
} else {
str.append("span class=\"disabled\"下一頁/span");
str.append("??");
}
if (this.pagecount 1 this.currentpage != this.pagecount) {
str.append("a href='" + url + "currentpage=" + pagecount
+ "' hidefocus=\"true\"尾頁/a");
str.append("??");
} else {
str.append("span class=\"disabled\"尾頁/span");
str.append("??");
}
str.append("/div");
}
return str.toString();
}
public String getParamUrl() {
String url = "";
url = this.request.getRequestURI().toString();
if (url.indexOf("?") == -1) {
url = url + "?";
}
String totalParams = "";
Enumeration params = this.request.getParameterNames();// 得到所有參數(shù)名
while (params.hasMoreElements()) {
String tempName = params.nextElement().toString();
String tempValue = this.request.getParameter(tempName);
if (tempValue != null !tempValue.equals("")
!tempName.equals("currentpage")) {
if (totalParams.equals("")) {
totalParams = totalParams + tempName + "=" + tempValue;
} else {
totalParams = totalParams + "" + tempName + "="
+ tempValue;
}
}
}
String totalUrl = url + totalParams;
return totalUrl;
}
}
真分頁:每次從數(shù)據(jù)庫里按照排序方法,取一段數(shù)據(jù),比如每頁20條,第一頁就是1-20 ,第二頁就是21-40。它是每次都從數(shù)據(jù)庫里查詢。都是最新的。假分頁:一次從數(shù)據(jù)庫里得到很多頁的數(shù)據(jù),然后緩存起來。比如每頁20條,一次取了100條,緩存起來。第一頁依然是1-20 ,第二頁就是21-40。到第6頁的時候,再從數(shù)據(jù)庫里取101-200條,在緩存起來。只不過,取數(shù)據(jù)的時候不是從數(shù)據(jù)庫里取了,而是在緩存里取。但是這個數(shù)據(jù)有可能不是最新的,因為不是直接從數(shù)據(jù)庫里查詢的。這種多用在更新不多的數(shù)據(jù)上。
可以定義一個實體類,該類包含ArrayList(n條記錄),havePre(是否有上一頁),havaNext(是否有下一個)和index(當(dāng)前頁碼)。然后去數(shù)據(jù)庫查數(shù)據(jù),將數(shù)據(jù)封裝成以上實體類就能實現(xiàn)了。
當(dāng)前題目:分頁查詢代碼java java分頁查詢原理思路
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