标签：span 返回 获得 abstract font port new connect nbsp
通用分页核心思路：
将上一次查询请求再发一次，只是当前页变了而已。
首页 1 2 3 4 … 100 末页 跳转
MySQL分页：select * from 表 limit 3,3
每页显示记录数 自己设置
当前页 来自前端
总页数 总记录数%每页显示记录数==0?总记录数/每页显示记录数:总记录数/每页显示记录数+1
总记录数 数据库统计count()
每页起始记录数 =（当前页-1）*每页显示记录数+1
总共101条记录，每页显示10条
第一页： 1-10
第二页： 11-20
第三页： 21-30
每页结尾记录数 =当前页*每页显示记录数
1、通用的查询方法代码实现
导入jar包
连接数据库之前查看自己的用户名、密码、数据库名是否正确
Book.java
package com.huangyucan.util; public class PageBean { private int page = 1;// 页码 private int rows = 10;// 页大小 private int total = 0;// 总记录数 private boolean pagination = true;// 是否分页 public PageBean() { super(); } public int getPage() { return page; } public void setPage(int page) { this.page = page; } public int getRows() { return rows; } public void setRows(int rows) { this.rows = rows; } public int getTotal() { return total; } public void setTotal(int total) { this.total = total; } public void setTotal(String total) { this.total = Integer.parseInt(total); } public boolean isPagination() { return pagination; } public void setPagination(boolean pagination) { this.pagination = pagination; } /** * 获得起始记录的下标 * * @return */ public int getStartIndex() { return (this.page - 1) * this.rows; } @Override public String toString() { return "PageBean [page=" + page + ", rows=" + rows + ", total=" + total + ", pagination=" + pagination + "]"; } }
BookDao.java
package com.huangyucan.dao; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList; import java.util.List; import com.zking.pageBean.entity.Book; import com.zking.pageBean.util.BaseDao; import com.zking.pageBean.util.BaseEntityDao; import com.zking.pageBean.util.DBAccess; import com.zking.pageBean.util.PageBean; import com.zking.pageBean.util.StringUtils; public class BookDao extends BaseEntityDao<Book>{ // /** // * // * @param book 带条件查询需要用上 // * @param pageBean 分页 // * @return // * @throws SQLException // */ // public List<Book> list(Book book,PageBean pageBean) throws SQLException{ // List<Book> list = new ArrayList<>(); // String sql = "select * from t_mvc_book where true"; // if(StringUtils.isNotBlank(book.getBname())) { // sql += " and bname like ‘%"+book.getBname()+"%‘"; // } //// System.out.println(sql); // Connection con = DBAccess.getConnection(); // PreparedStatement pst = con.prepareStatement(sql); // ResultSet rs = pst.executeQuery(); // while(rs.next()) { // list.add(new Book(rs.getInt("bid"), rs.getString("bname"), rs.getFloat("price"))); // } // return list; // } // /** // * oop改造后的方法 // * @param book // * @param pageBean // * @return // * @throws SQLException // * @throws IllegalAccessException // * @throws InstantiationException // */ // public List<Book> list(Book book,PageBean pageBean) throws SQLException, InstantiationException, IllegalAccessException{ // String sql = "select * from t_mvc_book where true"; // if(StringUtils.isNotBlank(book.getBname())) { // sql += " and bname like ‘%"+book.getBname()+"%‘"; // } // return executeQuery(sql, pageBean, new CallBack() { // @Override // public List<Book> foreach(ResultSet rs) throws SQLException { // List<Book> list = new ArrayList<>(); // while(rs.next()) { // list.add(new Book(rs.getInt("bid"), rs.getString("bname"), rs.getFloat("price"))); // } // return list; // } // }); // } /** * 利用反射对查询进行二次增强 * @param book * @param pageBean * @return * @throws SQLException * @throws InstantiationException * @throws IllegalAccessException */ public List<Book> list(Book book,PageBean pageBean) throws SQLException, InstantiationException, IllegalAccessException{ String sql = "select * from t_mvc_book where true"; if(StringUtils.isNotBlank(book.getBname())) { sql += " and bname like ‘%"+book.getBname()+"%‘"; } return executeQuery(sql, pageBean, Book.class); } }
BaseDao
package com.huangyucan.util; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList; import java.util.List; import com.zking.pageBean.entity.Book; public class BaseDao<T> { /** * 借鉴ajax的回调函数现象 * 在调用方去处理返回的结果集 * @author Administrator * */ public abstract class CallBack{ public abstract List<T> foreach(ResultSet rs) throws SQLException, InstantiationException, IllegalAccessException; } /** * 利用oop思想对原有的查询方法向上抽取共性部分 * @param sql * @param pageBean * @return * @throws SQLException * @throws IllegalAccessException * @throws InstantiationException */ public List<T> executeQuery(String sql, PageBean pageBean, CallBack callBack) throws SQLException, InstantiationException, IllegalAccessException{ List<T> list = new ArrayList<>(); Connection con = DBAccess.getConnection(); String countSql = getCountSql(sql); PreparedStatement pst = con.prepareStatement(countSql); ResultSet rs = pst.executeQuery(); if(rs.next()) { pageBean.setTotal(rs.getString(1)); } DBAccess.close(null, pst, rs); String pageSql = getPageSql(sql, pageBean); PreparedStatement psmt = con.prepareStatement(pageSql); ResultSet rst = psmt.executeQuery(); return callBack.foreach(rst); } /** * 获取分页的sql语句 * @param sql 符合条件的查询语句 * @param pageBean 分页的实体类 * @return */ private String getPageSql(String sql,PageBean pageBean) { return sql + " limit "+ pageBean.getStartIndex() +"," + pageBean.getRows(); } /** * 获取符合查询条件的总记录数的sql * @param sql * @return */ private String getCountSql(String sql) { return "select count(*) from ("+ sql +") t"; } }
分页工具类
PageBase
package com.huangyucan.util; /** * 分页工具类 * */ public class PageBean { private int page = 1;// 页码 private int rows = 10;// 页大小 private int total = 0;// 总记录数 private boolean pagination = true;// 是否分页 public PageBean() { super(); } public int getPage() { return page; } public void setPage(int page) { this.page = page; } public int getRows() { return rows; } public void setRows(int rows) { this.rows = rows; } public int getTotal() { return total; } public void setTotal(int total) { this.total = total; } public void setTotal(String total) { this.total = Integer.parseInt(total); } public boolean isPagination() { return pagination; } public void setPagination(boolean pagination) { this.pagination = pagination; } /** * 获得起始记录的下标 * * @return */ public int getStartIndex() { return (this.page - 1) * this.rows; } @Override public String toString() { return "PageBean [page=" + page + ", rows=" + rows + ", total=" + total + ", pagination=" + pagination + "]"; } }
标签：span 返回 获得 abstract font port new connect nbsp
原文地址：https://www.cnblogs.com/bf6rc9qu/p/11057860.html
