Servlet achieves paging effect, servlet implements Paging
The examples in this article share the code for implementing the paging Effect of Servlet for your reference. The details are as follows:
Paging algorithm:
Four variables need to be defined for their respective use
Int pageSize: How many records are displayed on each page
Int pageNow: page number to be displayed
Int pageCount: Total number of pages
Int rowCount: Total number of records
Note:
PageSize is specified, and pageNow is the user's choice.
RowCount is obtained from the table query.
PageCount is calculated. The formula is as follows:
if(rowCount%pageSize==0) { pageCount=rowCount/pageSize; } else { pageCount=rowCount/pageSize+1; }
If you use the statement: select field name list from table name where id? And?
This SQL statement is indeed fast, but there is a problem, that is, if the table id is deleted, a page may have one fewer record.
Therefore, the final method is as follows:
Select top pageSize field name list from table name where id not in (select top pageSize * (pageNow-1) id from table name)
Implementation Code:
Import javax. servlet. http. *; import java. io. *; import java. SQL. *; public class fenye extends HttpServlet {public void doGet (HttpServletRequest req, HttpServletResponse res) {Connection ct = null; PreparedStatement ps = null; ResultSet rs = null; int pageSize = 3; // The number of records that you want to display on each page int pageNow = 1; // initialize the current page as the first page int pageCount = 0; // the total number of pages, you need to know through calculation that int rowCount = 0; // The total number of records, the query table knows String sPageNow = req. getParameter ("pageNow "); // Receive the passed current page if (sPageNow! = Null) // if a non-null value is received, convert it to an Integer {pageNow = Integer. parseInt (sPageNow);} try {PrintWriter pw = res. getWriter (); Class. forName ("com. microsoft. sqlserver. jdbc. SQLServerDriver "); ct = DriverManager. getConnection ("jdbc: sqlserver: // 127.0.0.1: 1433; DatabaseName = Students", "sa", "password"); ps = ct. prepareStatement ("select count (*) from [Students]. [dbo]. [Students] "); // obtain the total number of records in the table rs1_ps.exe cuteQuery (); while (rs. next () {rowCount = r S. getInt (1); // obtain the total number of records in the table} if (rowCount % pageSize = 0) // calculate the total number of pages {pageCount = rowCount/pageSize ;} else {pageCount = rowCount/pageSize + 1;} ps = ct. prepareStatement ("select top" + pageSize + "* from [Students]. [dbo]. [Students] where id not in (select top "+ pageSize * (pageNow-1) +" id from [Students]. [dbo]. [Students]) "); rs1_ps.exe cuteQuery (); pw. println ("<body> <center>"); // displays the query result in the form of a table pw. println ("<table border = 1 "); pw. println ("<tr> <th> id </th> <th> name </th> <th> grade </th> </tr> "); while (rs. next () {pw. println ("<tr>"); pw. println ("<td>" + rs. getInt (1) + "</td>"); pw. println ("<td>" + rs. getString (2) + "</td>"); pw. println ("<td>" + rs. getString (3) + "</td>"); pw. println ("</tr>");} pw. println ("</table>"); if (pageNow = 1) // the previous page hyperlink. When you have already jumped to the first page, the page will not change {pw. println ("<a href = fenye? PageNow = "+ pageNow +"> "+" forward "+" </a> ");} When else // does not jump to the first page, each time you click a hyperlink, page jump forward once {pw. println ("<a href = fenye? PageNow = "+ (pageNow-1) +"> "+" forward "+" </a> ");} if (pageCount <= 5) // control the number of page hyperlinks displayed {for (int I = 1; I <= pageCount; I ++) {pw. println ("<a href = fenye? PageNow = "+ I +"> "+ I +" </a> ") ;}} else if (pageCount-pageNow <= 5) {for (int I = pageNow; I <= pageCount; I ++) pw. println ("<a href = fenye? PageNow = "+ I +"> "+ I +" </a> ");} else // when there are too many pages, for better page appearance, you need to control the number of display hyperlinks {for (int I = pageNow; I <= pageNow + 5; I ++) pw. println ("<a href = fenye? PageNow = "+ I +"> "+ I +" </a> ");} if (pageNow = pageCount) // when the last page is displayed, {pw. println ("<a href = fenye? PageNow = "+ pageNow +"> "+" backward "+" </a> ");} else {pw. println (" <a href = fenye? PageNow = "+ (pageNow + 1) +"> "+" backward "+" </a> ");} pw. println ("</center> </body>");} catch (Exception ex) {ex. printStackTrace () ;}} public void doPost (HttpServletRequest req, HttpServletResponse res) {this. doGet (req, res );}}
Execution result:
When the number of records per page is 3:
Click the corresponding connection to jump.
The last page is displayed as follows:
Code:
if(pageCount<=5) { for(int i=1;i<=pageCount;i++) { pw.println("<a href=fenye?pageNow="+i+">"+i+"</a>"); } }
Click backward.
To show how the program controls the number of page hyperlinks, change the number of records displayed on each page to 1.
The first page shows the effect:
Code:
else { for(int i=pageNow;i<=pageNow+5;i++) pw.println("<a href=fenye?pageNow="+i+">"+i+"</a>"); }
Display effect when the current page number increases gradually:
Code:
else if(pageCount-pageNow<=5) { for(int i=pageNow;i<=pageCount;i++) pw.println("<a href=fenye?pageNow="+i+">"+i+"</a>"); }
The above is all the content of this article. I hope it will be helpful for your learning and support for helping customers.
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