Java Operations Database: Paging query

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Or use the previous goods table to add some data

1. Entity class goods

//Encapsulating Data Public classGoods {Private intGID; PrivateString Gname; PrivateString Gprice; PrivateString gdate;  Public intGetgid () {returnGID; }     Public voidSetGid (intGID) {         This. GID =GID; }     PublicString Getgname () {returnGname; }     Public voidsetgname (String gname) { This. Gname =Gname; }     PublicString Getgprice () {returnGprice; }     Public voidSetgprice (String gprice) { This. Gprice =Gprice; }     PublicString getgdate () {returngdate; }     Public voidsetgdate (String gdate) { This. gdate =gdate; }     PublicGoods (intgid, String gname, String gprice, String gdate) {        Super();  This. GID =GID;  This. Gname =Gname;  This. Gprice =Gprice;  This. gdate =gdate; }     PublicGoods () {Super(); }}

2, DBHelper class

Importjava.sql.Connection;ImportJava.sql.DriverManager;Importjava.sql.PreparedStatement;ImportJava.sql.ResultSet;Importjava.sql.Statement;/*** Get connection objects for database operations * Close various resources for database operations *@authorYanchen **/ Public classDBHelper {Private Static FinalString className = "Com.mysql.jdbc.Driver"; Private Static FinalString url = "Jdbc:mysql://localhost:3306/test?characterencoding=utf8&usessl=true"; Private Static FinalString uname = "root"; Private Static FinalString UPass = ""; /*** Ways to get database connection objects*/     Public StaticConnection Getconn () {Connection conn=NULL; Try{class.forname (className); Conn=drivermanager.getconnection (Url,uname, UPass); } Catch(Exception e) {e.printstacktrace (); }                returnConn; }        /*** Close Database Connection object*/     Public Static voidCloseconn (Connection conn) {Try{            if(conn!=NULL) {conn.close (); }        } Catch(Exception e) {e.printstacktrace (); }    }        /*** Close Database Operations Object*/     Public Static voidclosestmt (Statement stmt) {Try{            if(stmt!=NULL) {stmt.close (); }        } Catch(Exception e) {e.printstacktrace (); }    }    /*** Close Database Operations Object*/     Public Static voidclosepstmt (PreparedStatement pstmt) {Try{            if(pstmt!=NULL) {pstmt.close (); }        } Catch(Exception e) {e.printstacktrace (); }    }        /*** Close Database Operations Object*/     Public Static voidClosers (ResultSet rs) {Try{            if(rs!=NULL) {rs.close (); }        } Catch(Exception e) {e.printstacktrace (); }    }}

3, implementation of class Goodsdao: operation of the database to query

Importjava.sql.Connection;Importjava.sql.PreparedStatement;ImportJava.sql.ResultSet;Importjava.util.ArrayList;Importjava.util.List; Public classGoodsdao {PrivateConnection conn =NULL; PrivatePreparedStatement pstmt =NULL; PrivateResultSet rs =NULL; //querying data for the current page     PublicList<goods> Getlistbycurpage (intcurpage) {List<Goods> list =NewArraylist<goods>(); Try{conn=Dbhelper.getconn (); intnum = (curPage-1); String SQL= "SELECT * FROM goods limit" +num+ ", 5"; Pstmt=conn.preparestatement (SQL); RS=Pstmt.executequery ();  while(Rs.next ()) {Goods ba=NewGoods (Rs.getint ("gid"), rs.getstring ("Gname"), Rs.getstring ("Gprice"), Rs.getstring ("Gdate")); Ba.setgid (Rs.getint ("GID"));            List.add (BA); }                    } Catch(Exception e) {e.printstacktrace (); } finally{dbhelper.closers (RS);            Dbhelper.closepstmt (PSTMT);        DBHELPER.CLOSECONN (conn); }                        returnlist; }        //query total number of records     Public intGetCount () {inti = 0; Try{conn=Dbhelper.getconn (); String SQL= "SELECT COUNT (*) CNT from goods"; Pstmt=conn.preparestatement (SQL); RS=Pstmt.executequery (); if(Rs.next ()) {i= Rs.getint ("CNT"); }                    } Catch(Exception e) {e.printstacktrace (); } finally{dbhelper.closers (RS);            Dbhelper.closepstmt (PSTMT);        DBHELPER.CLOSECONN (conn); }        returni; }}

4, Display class Goodsshow

Importjava.util.List;ImportJava.util.Scanner; Public classGoodsshow { Public Static voidMain (string[] args) {goodsshow bs=Newgoodsshow ();    Bs.show (); }        PrivateScanner input =NewScanner (system.in); PrivateGoodsdao DAO =NewGoodsdao (); intCurpage = 1; List<Goods> list =NULL;  Public voidShow () {intRowCount =Dao.getcount (); intPageCount = rowcount%5==0?rowcount/5:rowcount/5+1; List=dao.getlistbycurpage (curpage);                print (list); System.out.println ("Home" F "previous" P "Next" N "last" L "Please select:"); CharChoose = Input.next (). toUpperCase (). CharAt (0); Switch(choose) { CaseF: Curpage= 1;  Break;  CaseP: Curpage= CurPage-1; if(curpage<1) {Curpage= 1; }                 Break;  CaseN: Curpage= Curpage +1; if(curpage>PageCount) {Curpage=PageCount; }                 Break;  CaseL: Curpage=PageCount;  Break;    } show (); }         Public voidPrint (list<goods>list) {System.out.println ("No. \ t goods \ t price \ t Time");  for(intI=0;i<list.size (); i++) {System.out.println (List.get (i). Getgid ()+ "\ T" +list.get (i). Getgname () + "\ T" +list.get (i). Getgprice () + "\ T" +List.get (i). Getgdate ()); }    }}

Then ....

Java Operations Database: Paging query