分页查询代码java java分页查询原理思路
java 怎么分页?
通过rs.next()进行分页，首先用rs.absolute(0)定位到某条记录。然后循环取数例如：1-10 可以for(int i=0;i10;i++){rs.next()}
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谁能给我个完整的java 分页代码 谢谢了
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; // 当前是第几页
private int pagecount = 0; // 一共有多少页
private int rscount = 0; // 一共有多少行
private int pagesize = 10; // 每页有多少行[默认为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;
}
/**
* 传入SQL语句获取总记录数
*/
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;
}
/**
* 获取总页数
*
* @return int
*/
public int getPageCount() {
try {
this.pagecount = ((this.rscount - 1) / this.pagesize) + 1;
} catch (Exception ex) {
this.pagecount = 0;
}
return this.pagecount;
}
/**
* 获取当前页码的设置
*
* @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;
}
/**
* 分页工具条
*
* @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;
// 文字的分页
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("共有记录" + this.rscount + "条 ");
str.append("共" + this.pagecount + "页 ");
str.append("每页" + this.pagesize + "记录 ");
str.append("现在" + this.currentpage + "/" + this.pagecount + "页");
str.append("/tdtd");
if (this.currentpage 1) {
str.append("a href='" + url + "currentpage=1'首页/a");
str.append(" ");
str.append("a href='" + url + "currentpage=" + ProPage
+ "'上一页/a");
str.append(" ");
} else {
str.append("首页");
str.append(" ");
str.append("上一页");
str.append(" ");
}
if (this.currentpage this.pagecount) {
str.append("a href='" + url + "currentpage=" + Nextpage
+ "'下一页/a");
str.append(" ");
} else {
str.append("下一页");
str.append(" ");
}
if (this.pagecount 1 this.currentpage != this.pagecount) {
str.append("a href='" + url + "currentpage=" + pagecount
+ "'尾页/a");
str.append(" ");
} else {
str.append("尾页");
str.append(" ");
}
str.append("转到");
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页");
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)) {
/**
* 图片的分页
*/
} else if (flag.equals(PageDAO.BbsText)) {
/**
* 论坛形式的分页[直接以数字方式体现]
*/
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("记录" + this.rscount + "条 ");
str.append("共" + this.pagecount + "页 ");
str.append("每页" + this.pagesize + "记录 ");
str.append("现在" + this.currentpage + "/" + this.pagecount + "页");
str.append("/tdtd");
// 设定是否有首页的链接
if (this.currentpage 1) {
str.append("a href='" + url + "currentpage=1'首页/a");
str.append(" ");
}
// 设定是否有上一页的链接
if (this.currentpage 1) {
str.append("a href='" + url + "currentpage=" + ProPage
+ "'上一页/a");
str.append(" ");
}
// 如果总页数只有10的话
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 {
// 说明总数有超过10页
// 制定特环的开始页和结束页
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 {
// 表示从第一页开始算
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 ");
}
}
}
// 设定是否有下一页的链接
if (this.currentpage this.pagecount) {
str.append("a href='" + url + "currentpage=" + Nextpage
+ "'下一页/a");
str.append(" ");
}
// 设定是否有尾页的链接
if (this.pagecount 1 this.currentpage != this.pagecount) {
str.append("a href='" + url + "currentpage=" + pagecount
+ "'尾页/a");
str.append(" ");
}
str.append("/tdtd width='3%' /td/tr/table");
} else if (flag.equals(PageDAO.BbsImage)) {
/**
* 论坛形式的分页[以图片的方式体现]
*/
// 设定分页显示的CSS
str.append("style");
str
.append("BODY {FONT-SIZE: 12px;FONT-FAMILY:宋体;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\"");
// 判定是否有上一页
if (this.currentpage 1) {
str.append("a href='" + url
+ "currentpage=1' hidefocus=\"true\"首页/a");
str.append(" ");
str.append("a href='" + url + "currentpage=" + ProPage
+ "' hidefocus=\"true\"上一页/a");
str.append(" ");
} else {
str.append("span class=\"disabled\"首页/span");
str.append(" ");
str.append("span class=\"disabled\"上一页/span");
str.append(" ");
}
// 显示中间的图片
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 {
// 说明总数有超过10页
// 制定特环的开始页和结束页
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 {
// 表示从第一页开始算
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 ");
}
}
}
// 判断下一页和尾页
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\"下一页/a");
str.append(" ");
} else {
str.append("span class=\"disabled\"下一页/span");
str.append(" ");
}
if (this.pagecount 1 this.currentpage != this.pagecount) {
str.append("a href='" + url + "currentpage=" + pagecount
+ "' hidefocus=\"true\"尾页/a");
str.append(" ");
} else {
str.append("span class=\"disabled\"尾页/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();// 得到所有参数名
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;
}
}
JAVA项目中的真分页与假分页的代码怎么写~
真分页：每次从数据库里按照排序方法，取一段数据，比如每页20条，第一页就是1－20 ，第二页就是21－40。它是每次都从数据库里查询。都是最新的。假分页：一次从数据库里得到很多页的数据，然后缓存起来。比如每页20条，一次取了100条，缓存起来。第一页依然是1－20 ，第二页就是21－40。到第6页的时候，再从数据库里取101－200条，在缓存起来。只不过，取数据的时候不是从数据库里取了，而是在缓存里取。但是这个数据有可能不是最新的，因为不是直接从数据库里查询的。这种多用在更新不多的数据上。
用JAVA实现分页查询
可以定义一个实体类，该类包含ArrayList（n条记录），havePre（是否有上一页），havaNext（是否有下一个）和index（当前页码）。然后去数据库查数据，将数据封装成以上实体类就能实现了。
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