private int currentPage = 1; // 當(dāng)前頁
private int totalPages = 0; // 總頁數(shù)
private int pageRecorders = 5;// 每頁5條數(shù)據(jù)
private int totalRows = 0; // 總數(shù)據(jù)數(shù)
private int pageStartRow = 0;// 每頁的起始數(shù)
private int pageEndRow = 0; // 每頁顯示數(shù)據(jù)的終止數(shù)
private boolean hasNextPage = false; // 是否有下一頁
private boolean hasPreviousPage = false; // 是否有前一頁
private int nextPage = 0;//下一頁的頁碼
private int previousPage = 0;//上一頁的頁碼
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)總的頁數(shù)，（假設(shè)當(dāng)前頁為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;
}
然后在按下一頁或者上一頁的時(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;
}
}
在HTML中按下一頁或者上一頁的時(shí)候有如下代碼：
<logic:equal name="page" property="hasNextPage" value="true">
<html:link page="/List.do?action=nextPage">
nextPage
</html:link>
</logic:equal>
<logic:equal name="page" property="hasPreviousPage" value="true">
<html:link page="/List.do?action=previousPage">
PreviousPage
</html:link>
</logic:equal>
然后在Action中作如下處理：
String currentPage = request.getParameter("currentPage");
HttpSession session = request.getSession();
EmployeeForm employeeForm = (EmployeeForm) form;
String queryString = null;
String queryCon = null;
String action = employeeForm.getAction();
List list = new ArrayList();
PageBean pb = null;
EmployeeDao employeeDao = new EmployeeDao();
if(action == null || action.equals("null")){
int totalRows = employeeDao.getTotalRows();
pb = new PageBean(totalRows);
session.removeAttribute("page");
queryString = employeeForm.getQueryString();
queryCon = employeeForm.getQueryCon();
session.setAttribute("queryString",queryString);
session.setAttribute("queryCon",queryCon);
list = employeeDao.getAllEmployee(queryString, queryCon,
String.valueOf(pb.getPageStartRow()),
String.valueOf(pb.getPageRecorders()));
}else if(action.equals("nextPage")){
queryString = (String)session.getAttribute("queryString");
queryCon = (String)session.getAttribute("queryCon");
employeeForm.setQueryString(queryString);
employeeForm.setQueryCon(queryCon);
pb = (PageBean)session.getAttribute("page");
pb.nextPage();
list = employeeDao.getAllEmployee(queryString, queryCon,
String.valueOf(pb.getPageStartRow()),
String.valueOf(pb.getPageRecorders()));
}else if(action.equals("previousPage")){
queryString = (String)session.getAttribute("queryString");
queryCon = (String)session.getAttribute("queryCon");
employeeForm.setQueryString(queryString);
employeeForm.setQueryCon(queryCon);
pb = (PageBean)session.getAttribute("page");
pb.previousPage();
list = employeeDao.getAllEmployee(queryString, queryCon,
String.valueOf(pb.getPageStartRow()),
String.valueOf(pb.getPageRecorders()));
}
pb.description();
session.setAttribute("page",pb);
request.setAttribute("admin", "admin");
request.setAttribute("employee", list);
return mapping.findForward("showlist");
然后在數(shù)據(jù)庫查詢中有如下代碼：
/**
*查詢總記錄數(shù)
*/
public int getTotalRows() {
int totalRows = 0;
String sql = "select count(*) from employee";//假設(shè)是員工表
Database db = new Database();
ResultSet rs = db.executeQuery(sql);
try {
while (rs.next()) {
String id = (String) rs.getString(1);
totalRows = Integer.parseInt(id);
}
} catch (SQLException e) {
e.printStackTrace();
}
db.close();
return totalRows;
}
/*
*查詢每一頁需要查詢的頁碼
*/
public List getAllEmployee(String queryString, String queryCon,String startRow,String num) {
List list = new ArrayList();
String sql = null;
if (queryString == null || queryString.equals("")) {
sql = "select * from employee,dept " +
"where dept.Id = employee.deptId " +
"order by employee.id asc"+ " limit "+startRow+","+num;
} else {
sql = "select * from employee,dept " +
"where dept.Id = employee.deptId order by employee."
+ queryString + " " + queryCon + " limit "+startRow+","+num;
}
Employee employee = null;
Database db = new Database();
ResultSet rs = db.executeQuery(sql);
try {
while (rs.next()) {
String id = (String) rs.getString("employee.id");
String name = (String) rs.getString("employee.name");
String deptId = (String) rs.getString("employee.deptId");
String deptName = (String) rs.getString("dept.deptName");
employee = new Employee();
employee.setId(id);
employee.setName(name);
employee.setDeptId(deptId);
employee.setDeptName(deptName);
list.add(employee);
}
} catch (SQLException e) {
e.printStackTrace();
}
db.close();
return list;
}
這里我用了hibernate進(jìn)行數(shù)據(jù)庫操作，你也可以用jdbc進(jìn)行操作，情況類似。
二，根據(jù)總的頁數(shù)，當(dāng)前頁
這樣的話構(gòu)造函數(shù)應(yīng)該寫成:
public PageBean(int totalRows,int currentPage) {
this.totalRows = totalRows;
this.currentPage = currentPage;
if(currentPage < 2)
hasPreviousPage = false;
else
hasPreviousPage = true;
if ((totalRows % pageRecorders) == 0) {
totalPages = totalRows / pageRecorders;
} else {
totalPages = totalRows / pageRecorders + 1;
}
if (currentPage < totalPages) {
hasNextPage = true;
nextPage = currentPage + 1;
pageStartRow = (currentPage - 1)*pageRecorders;
this.pageEndRow = pageStartRow + pageRecorders;
} else if(currentPage == totalPages){
pageStartRow = (currentPage - 1)*pageRecorders;
this.pageEndRow = totalRows;
hasNextPage = false;
nextPage = currentPage;
}
if(currentPage < 2){
previousPage = currentPage;
hasPreviousPage = false;
}else if(currentPage > 1){
previousPage = currentPage-1;
hasPreviousPage = true;
}
}
在action中應(yīng)該寫成
if(currentPage == null){
pb = new PageBean(totalRows);
session.removeAttribute("page");
queryString = employeeForm.getQueryString();
queryCon = employeeForm.getQueryCon();
session.setAttribute("queryString",queryString);
session.setAttribute("queryCon",queryCon);
list = employeeDao.getAllEmployee(queryString, queryCon,
String.valueOf(pb.getPageStartRow()),
String.valueOf(pb.getPageRecorders()));
}
else{
pb = new PageBean(totalRows,Integer.parseInt(currentPage));
queryString = employeeForm.getQueryString();
queryCon = employeeForm.getQueryCon();
session.setAttribute("queryString",queryString);
session.setAttribute("queryCon",queryCon);
list = employeeDao.getAllEmployee(queryString, queryCon,
String.valueOf(pb.getPageStartRow()),
String.valueOf(pb.getPageRecorders()));
}
session.setAttribute("page",pb);
request.setAttribute("admin", "admin");
request.setAttribute("employee", list);
return mapping.findForward("showlist");
在jsp中應(yīng)該寫成：
<logic:equal name="page" property="hasNextPage" value="true">
<a href="List.do?currentPage=<bean:write name="page" property="nextPage"/>">
nextPage
</a>
</logic:equal>
<logic:equal name="page" property="hasPreviousPage" value="true">
|
<a href="/test/List.do?currentPage=<bean:write name="page" property="previousPage"/>">
PreviousPage
</a>
</logic:equal>
數(shù)據(jù)庫查詢部分依然適用。
