Java分页代码的独立实现

╰半夏微凉° 2022-06-03 10:11 203阅读 0赞

在项目中，分页是一个项目中必不可少的，它可以防止我们从数据库中进行大量数据查询时速度变慢，提高我们的查询效率

1、定义分页模型：PageModel

package com.common.page;  
          
        import java.util.List;  
          
        /** 
         * 封装分页信息 
         * @author Administrator 
         * 
         */  
        public class PageModel<E> {  
          
            //结果集  
            private List<E> list;  
              
            //查询记录数  
            private int totalRecords;  
              
            //每页多少条数据  
            private int pageSize;  
              
            //第几页  
            private int pageNo;  
              
            /** 
             * 总页数 
             * @return 
             */  
            public int getTotalPages() {  
                return (totalRecords + pageSize - 1) / pageSize;  
            }  
              
            /** 
             * 取得首页 
             * @return 
             */  
            public int getTopPageNo() {  
                return 1;  
            }  
              
            /** 
             * 上一页 
             * @return 
             */  
            public int getPreviousPageNo() {  
                if (pageNo <= 1) {  
                    return 1;  
                }  
                return pageNo - 1;  
            }  
              
            /** 
             * 下一页 
             * @return 
             */  
            public int getNextPageNo() {  
                if (pageNo >= getBottomPageNo()) {  
                    return getBottomPageNo();  
                }  
                return pageNo + 1;    
            }  
              
            /** 
             * 取得尾页 
             * @return 
             */  
            public int getBottomPageNo() {  
                return getTotalPages();  
            }  
              
            public List<E> getList() {  
                return list;  
            }  
          
            public void setList(List<E> list) {  
                this.list = list;  
            }  
          
            public int getTotalRecords() {  
                return totalRecords;  
            }  
          
            public void setTotalRecords(int totalRecords) {  
                this.totalRecords = totalRecords;  
            }  
          
            public int getPageSize() {  
                return pageSize;  
            }  
          
            public void setPageSize(int pageSize) {  
                this.pageSize = pageSize;  
            }  
          
            public int getPageNo() {  
                return pageNo;  
            }  
          
            public void setPageNo(int pageNo) {  
                this.pageNo = pageNo;  
            }  
        }

2、分页测试：在MySQL中建立admin表，里面有字段id、name、password

3、简历Admin的实体bean类：

package com.common.page;  
          
        public class Admin {  
            private int id;  
            private String name;  
            private String password;  
            public int getId() {  
                return id;  
            }  
            public void setId(int id) {  
                this.id = id;  
            }  
            public String getName() {  
                return name;  
            }  
            public void setName(String name) {  
                this.name = name;  
            }  
            public String getPassword() {  
                return password;  
            }  
            public void setPassword(String password) {  
                this.password = password;  
            }  
          
        }

4、测试调用：

package com.common.page;  
          
        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.common.db.DbUtil;  
          
        public class Client {  
            public static PageModel findAdmins(int pageNo,int pageSize){  
                Connection conn=DbUtil.getConnection();  
                String sql="select * from admin limit ?,?";  
                PageModel pageModel=null;  
                PreparedStatement pstm=null;  
                ResultSet rs=null;  
                Admin admin=null;  
                List<Admin> list=new ArrayList<Admin>();  
                try {  
                    pstm=conn.prepareStatement(sql);  
                    pstm.setInt(1, (pageNo-1)*pageSize);  
                    pstm.setInt(2, pageNo*pageSize);  
                    rs=pstm.executeQuery();;  
                    while(rs.next()){  
                        admin=new Admin();  
                        admin.setId(rs.getInt("a_id"));  
                        admin.setName(rs.getString("a_name"));  
                        admin.setPassword(rs.getString("a_pwd"));  
                        list.add(admin);  
                    }  
                    ResultSet rs2=pstm.executeQuery("select count(*) from admin");  
                    int total=0;  
                    if(rs2.next()){  
                        total=rs2.getInt(1);  
                    }  
                    pageModel=new PageModel();  
                    pageModel.setPageNo(pageNo);  
                    pageModel.setPageSize(pageSize);  
                    pageModel.setTotalRecords(total);  
                    pageModel.setList(list);  
                } catch (SQLException e) {  
                    e.printStackTrace();  
                }finally{  
                    DbUtil.close(conn);  
                    DbUtil.close(pstm);  
                    DbUtil.close(rs);  
                }  
                return pageModel;  
            }  
              
            public static void main(String[] args) {  
                PageModel pageModel=Client.findAdmins(2,4);  
                List<Admin> list=pageModel.getList();  
                for(Admin a:list){  
                    System.out.print("ID:"+a.getId()+",用户名:"+a.getName()+",密码:"+a.getPassword());  
                    System.out.println();  
                }  
                System.out.print("当前页:"+pageModel.getPageNo()+" ");  
                System.out.print("共"+pageModel.getTotalPages()+"页  ");  
                System.out.print("首页:"+pageModel.getTopPageNo()+" ");  
                System.out.print("上一页:"+pageModel.getPreviousPageNo()+" ");  
                System.out.print("下一页:"+pageModel.getNextPageNo()+" ");  
                System.out.print("尾页:"+pageModel.getBottomPageNo()+" ");  
                System.out.print("共"+pageModel.getTotalRecords()+"条记录");  
                System.out.println();  
            }  
          
        }

这样分页效果就实现了，我们要实现分页效果，只要传入相应的参数和相应的数据库执行语句即可实现，希望大家能灵活运用。  
  
转自：http://blog.csdn.net/harderxin/article/details/7731313