java仿谷歌分页

    昨天写了几个分页后，今天仿写谷歌的分页！其中遇到了算法和对象封装的问题，其中重要的是算法的选择。

下面分享一下我的主要代码：

javaBean中的Student和Pagelei。

student类：

Code:
import java.io.Serializable;   
  
public class Student implements Serializable {   
  
    /**  
     *   
     */  
    private static final long serialVersionUID = 1L;   
       
    //成员属性   
    private int id;  //递增的id序列   
    private String name;//名称   
    private int age;//年龄   
    private String email;//邮箱   
       
       
    public Student(){   
           
    }   
       
    public Student(String name,int age,String email){   
        this.name=name;   
        this.age=age;   
        this.email=email;   
    }   
  
    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 int getAge() {   
        return age;   
    }   
  
    public void setAge(int age) {   
        this.age = age;   
    }   
  
    public String getEmail() {   
        return email;   
    }   
  
    public void setEmail(String email) {   
        this.email = email;   
    }   
  
       
       
}  

Page类：

Code:
import java.util.List;   
  
public class Page {   
       
    private int nowpage;//当前页   
    private int countrecord;//总记录数   
    private int countpage;//总页数   
       
       
    public static final int PAGESIZE=5;//每页显示的记录数   
       
       
    private int sumindex =6;//索引的sum值   
    private int startindex = 1;//开始的索引值   
    private int endindex = 3;//结束的索引值   
       
       
    private List allentities;   
       
    public Page(){   
           
    }   
       
    public void index(int nowpage){ //可变   
        /*计算出索引的位置  
         *   
         * */  
        this.endindex = nowpage+2;   
        if(this.endindex-5>0){   
            if(this.endindex <= this.countpage){   
                this.startindex = this.endindex-5;   
            }else{   
                this.endindex = this.countpage;   
                this.startindex = this.endindex-5;   
            }   
        }else{   
            this.startindex = 1;   
        }   
    }   
       
    public int getNowpage() {   
        return nowpage;   
    }   
    public void setNowpage(int nowpage) {   
        this.nowpage = nowpage;   
    }   
    public int getCountrecord() {   
        return countrecord;   
    }   
    public void setCountrecord(int countrecord) {   
        this.countrecord = countrecord;   
    }   
    public int getCountpage() {   
        return countpage;   
    }   
    public void setCountpage(int countpage) {   
        this.countpage = countpage;   
    }   
    public int getStartindex() {   
        return startindex;   
    }   
    public void setStartindex(int startindex) {   
        this.startindex = startindex;   
    }   
    public int getEndindex() {   
        return endindex;   
    }   
    public void setEndindex(int endindex) {   
        this.endindex = endindex;   
    }   
    public List getAllentities() {   
        return allentities;   
    }   
    public void setAllentities(List allentities) {   
        this.allentities = allentities;   
    }   
  
    public int getSumindex() {   
        return sumindex;   
    }   
  
    public void setSumindex(int sumindex) {   
        this.sumindex = sumindex;   
    }   
  
}  

逻辑处理类：

Code:
public class ListStusServlet extends HttpServlet {   
  
    @Override  
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)   
            throws ServletException, IOException {   
        this.doPost(req, resp);   
    }   
  
    @Override  
    protected void doPost(HttpServletRequest req, HttpServletResponse resp)   
            throws ServletException, IOException {   
       //1.设置编码   
        req.setCharacterEncoding("utf8");   
           
  
           
       //2.获取当前页   
        Page stupage = new Page();   
        int nowpage=1;   
        String npage = req.getParameter("nowpage");   
           
        if(npage!=null){   
            nowpage = Integer.valueOf(npage);   
        }   
           
           
           
        //3、创建sevice服务操作对象   
        StudentServiceImpl ssi = new StudentServiceImpl();   
           
        int lastpage = ssi.getCountPage();   
           
           
       
        List<Student> allentities = ssi.getNowPageInfo(nowpage);   
           
        stupage.setCountpage(lastpage);   
        stupage.setNowpage(nowpage); //存入到page中   
        stupage.setAllentities(allentities);//将结果集放进page中   
        stupage.index(nowpage);   
        System.out.println("页码是："+nowpage+"-start："+stupage.getStartindex()+" / end："+stupage.getEndindex());   
        req.setAttribute("stupage", stupage);   
           
           
        req.getRequestDispatcher("liststs.jsp").forward(req, resp);   
    }   
  
}  

操作类：

Code:
public class StudentDaoImpl implements StudentDao {   
  
    // 数据库操作的对象   
    private Connection conn;   
    private PreparedStatement pstmt;   
    private ResultSet rs;   
    // 每页显示的记录数   
    private static final int PAGESIZE = 5;   
  
    // 获取总页数   
    public int getCountPage() {   
        return getCountRecord() % PAGESIZE == 0 ? getCountRecord() / PAGESIZE   
                : getCountRecord() / PAGESIZE + 1;   
    }   
  
    // 获取总记录   
    public int getCountRecord() {   
        // 1、定义返回结果   
        int countrecord = 0;   
        // 2、获取数据库连接对象   
        conn = DBConn.getConn();   
        // 3、创建预处理的sql语句   
        String sql = "select count(*) from student";   
  
        try {   
            // 4、根据预处理的sql语句创建预处理的操作对象   
            pstmt = conn.prepareStatement(sql);   
            // 5、查询的时候 直接执行   
            rs = pstmt.executeQuery();   
            // 6、判断   
            if (rs.next()) {   
                countrecord = rs.getInt(1);   
            }   
        } catch (SQLException e) {   
            e.printStackTrace();   
        } finally {   
            DBConn.close(rs, pstmt);   
        }   
        return countrecord;   
    }   
  
    // 获取当前页信息   
    public List<Student> getNowPageInfo(int nowpage) {   
        //1、定义返回结果变量   
        List<Student> allentities = new ArrayList<Student>();   
        //2、获取连接对象   
        conn = DBConn.getConn();   
         try {   
             //3、根据预处理的sql语句创建预处理的操作对象   
            pstmt = conn.prepareStatement("select id,name,age,email from student limit ?,?");   
             //4、定义下标变量 并赋值   
            int index = 1;   
            pstmt.setInt(index++, (nowpage-1)*PAGESIZE);   
            pstmt.setInt(index++, PAGESIZE);   
            //5、查询的时候 直接执行   
            rs = pstmt.executeQuery();   
            //判断   
            while(rs.next()){   
                //创建实体bean对象   
                Student entity = new Student();   
                entity.setId(rs.getInt("id"));   
                entity.setName(rs.getString("name"));   
                entity.setAge(rs.getInt("age"));   
                entity.setEmail(rs.getString("email"));   
                //添加到集合中   
                allentities.add(entity);   
            }   
         } catch (SQLException e) {   
            e.printStackTrace();   
        }finally{   
            DBConn.close(rs, pstmt);   
        }   
        return allentities;   
    }   
  
    public static void main(String[] args) {   
        StudentDaoImpl sdi = new StudentDaoImpl();   
  
/*      int countrecord = sdi.getCountRecord();  
 
        System.out.println(countrecord);  
          
        System.out.println(sdi.getCountPage());*/  
           
        List<Student> allentities = sdi.getNowPageInfo(7);   
           
        for(Student entity : allentities){   
            System.out.println(entity.getName());   
        }   
           
           
    }   
  
}  

总结：今天的感觉是：学习很重要，要多动脑，多练习！