8.22 java pagination and SQL statement

In class yesterday, we learned how to make our system page query, here we will use the limit of SQL.
1. First, let's create a new java file named PageBean.

package com.zhongruan.bean;
import java.util.List;
public class PageBean<T> {
    private int currentPage;
    private int pageSize;
    private List<T> musics;
    private int totalCount;
    private int totalPage;
public int getCurrentPage() {
        return currentPage;
    }
public void setCurrentPage(int currentPage) {
        this.currentPage = currentPage;
    }
 public int getPageSize() {
        return pageSize;
    }
     public void setPageSize(int pageSize) {
        this.pageSize = pageSize;
    }
     public List<T> getMusics() {
        return musics;
    }
     public void setMusics(List<T> musics) {
        this.musics = musics;
    }
     public int getTotalCount() {
        return totalCount;
    }
     public void setTotalCount(int totalCount) {
        this.totalCount = totalCount;
    }
 public int getTotalPage() {
        return totalPage;
    }
 public void setTotalPage(int totalPage) {
        this.totalPage = totalPage;
    }
    @Override
    public String toString() {
        return "PageBean{" +
                "currentPage=" + currentPage +
                ", pageSize=" + pageSize +
                ", musics=" + musics +
                ", totalCount=" + totalCount +
                ", totalPage=" + totalPage +
                '}';
    }
     }

Here are some variables we will use.
We put some query pagination code in MusicService:

  if (j == 1) {
            System.out.println("-------欢迎进入音乐管理系统-------");
            System.out.println("\t1.查询音乐\t2.添加音乐\t3.修改音乐\t4.删除音乐\t5.返回上一层");
            int a = input.nextInt();
            switch (a) {
                case 1:
                    int count = musicDao.getCount();
                    pageBean.setTotalCount(count);
                    double ceil = Math.ceil(count / 5.0);//12  5   2.4    3   2  2  2.1  3
                    int totalPage= (int) ceil;
                    pageBean.setTotalPage(totalPage);
                    System.out.println("请问你要查询第几页：我们一共有"+totalPage+"页");
                    int i=input.nextInt();
                    List<Music> music1 = getMusic(i, totalPage, musicDao);
                    System.out.println("下一步还要做什么：\t1.上一页 \t2.下一页 \t3.退出");
                    int i1 = input.nextInt();
                    switch (i1){
                        case 1:
                            if(i==1){
                                getMusic(1, totalPage, musicDao);
                            }else{
                                getMusic(i-1, totalPage, musicDao);
                            }
                         break;

Connect to the database and SQL statement:

public int getCount() throws SQLException{
    Connection connection=DBUtil.getconnection();
    connection.prepareStatement("select count (*) from music");
    PreparedStatement statement=null;
    ResultSet resultSet=statement.executeQuery();
    int count=0;
    while (resultSet.next()){
        count = resultSet.getInt(1);
    }
    DBUtil.closeAll(resultSet,statement,connection);
    return count;
}