The input box displays the news list by PAGE (1) and the News list by page.

The input box displays the news list by PAGE (1) and the News list by page.
Today, I learned how to use the paging technology in the news and publishing system to display pages by page. I feel that it is very difficult to do it at first, and I need to do it gradually and slowly. Step 1: determine the number of data displayed on each page. 2. Calculate the number of pages displayed. 3. Write an SQL statement. Step 1: connect to the database.

Import java. SQL. connection; import java. SQL. driverManager; import java. SQL. preparedStatement; import java. SQL. resultSet; import java. SQL. SQLException; import java. util. arrayList; import java. util. list;/*** database Connection help class * @ author zql_pc * Singleton design mode */public class DbHelp {// database Connection object private Connection conn = null; // database Connection help public Connection lianjie () {if (conn = null) {// Database Configuration String driver = "oracle. jdbc. driver. oracleDriver "; // driver String url =" jdbc: oracle: thin: @ localhost: 1521: NEWS "; // url String username =" epet "; // username String password = "123456"; // password // 1. load the driver Class try {Class. forName (driver); // 2. establish connection conn = DriverManager. getConnection (url, username, password);} catch (ClassNotFoundException e) {e. printStackTrace ();} catch (SQLException e) {e. printStackTrace () ;}} return conn ;}}

Step 2: write news entity classes for encapsulation

/*** News entity class ** @ author zql_pc **/public class news {private int id; private int t_id; private String title; private String author; private String createdate; private String picpath; private String content; private String modifydate; private String summay; public int getId () {return id;} public void setId (int id) {this. id = id;} public int getT_id () {return t_id;} public void setT_id (int tId) {t_id = tId;} public String getTitle () {return title ;} public void setTitle (String title) {this. title = title;} public String getAuthor () {return author;} public void setAuthor (String author) {this. author = author;} public String getCreatedate () {return createdate;} public void setCreatedate (String createdate) {this. createdate = createdate;} public String getPicpath () {return picpath;} public void setPicpath (String picpath) {this. picpath = picpath;} public String getContent () {return content;} public void setContent (String content) {this. content = content;} public String getModifydate () {return modifydate;} public void setModifydate (String modifydate) {this. modifydate = modifydate;} public String getSummay () {return summay;} public void setSummay (String summay) {this. summay = summay ;}}

Step 3: Query news

Import java. SQL. connection; import java. SQL. preparedStatement; import java. SQL. resultSet; import java. SQL. SQLException; import java. SQL. statement; import java. util. arrayList; import java. util. list;/*** query news * @ author zql_pc **/public class SelectNews {DbHelp help = new DbHelp (); // query news count public int newsCount () throws SQLException {// query the news entry Connection con = help. lianjie (); // create a database operation object Statement st = co N. createStatement (); String SQL = "select count (*) from news"; // obtain the result set ResultSet rs = st.exe cuteQuery (SQL); // The number of news int newsCount = 0; while (rs. next () {newsCount = rs. getInt (1) ;}return newsCount;} // calculate the public int getPages (int newsSize) throws SQLException {int newsCount = newsCount (); int num = (newsCount % newsSize = 0 )? NewsCount/newsSize: newsCount/newsSize + 1; return num;} // query news public List <news> getList (int pageIndex, int newsSize) as required) throws SQLException {// calculate the upper and lower limits // page 1st 1-5 // 2 6-10 int up = newsSize * pageIndex; int down = newsSize * (pageIndex-1) + 1; // obtain the Connection con = help. lianjie (); String SQL = "select * from" + "(select n. *, rownum r from "+" (select * from news order by ncreatedate desc) N "+" where rownum <= ?) Where r> =? "; PreparedStatement pst = con. prepareStatement (SQL); pst. setInt (1, up); pst. setInt (2, down); // obtain the result set ResultSet rs = pst.exe cuteQuery (); // create a List of news objects containing the set <news> list = new ArrayList <news> (); while (rs. next () {// create a news object news = new news (); news. setTitle (rs. getString ("ntitle"); news. setCreatedate (rs. getString ("ncreatedate"); list. add (news) ;}return list ;}}

Step 4: display on page

<% @ Page language = "java" import = "java. util. * "pageEncoding =" UTF-8 "%> <% @ page import =" tools. selectNews "%> <% @ page import =" tools. news "%> <! Doctype html public "-// W3C // dtd html 4.01 Transitional // EN">