pagination.java

jsp实现网络教育系统

package org.jetic.web;

import java.sql.ResultSet;
import java.sql.Statement;

/**
 * Title:        经天科技
 * Description:
 * Copyright:    Copyright (c) 2001
 * Company:      www.jetic.org 经天
 * @author hover
 * @version 1.0
 */

public class Pagination {
    private Statement stmt;
    private String sql = "";
    private String table = "";
    private String fields = "";
    private int recordcount = 0;
    private int pagesize = 10;
    private int pagecount = 0;
    private int page = 1;
    private String condition = "";
    private boolean direction = true;

    public Pagination() {
    }
    public Pagination(int pagesize) {
        setPagesize(pagesize);
    }
    public Pagination(Statement stmt) {
        setStmt(stmt);
    }

    public String getSql() {
        String strCondition = "";
        String order1, order2;

        if (condition.length() > 0) strCondition = " WHERE " + condition;

        // 计算页数
        sql = "SELECT COUNT(*) FROM " + table + strCondition;
        try {
            ResultSet rs = stmt.executeQuery(sql);
            if (rs.next())  recordcount = rs.getInt(1);
            rs.close();
        }
        catch (Exception ex) {
            ex.printStackTrace(System.err);
        }
        if (recordcount < 1)
            pagecount = 0;
        else
            pagecount = (recordcount - 1) / pagesize + 1;

        if (page < 1)
            page = 1;
        else if (page > pagecount)
            page = pagecount;

        if (direction) {
            order1 = " ORDER BY [ID]";
            order2 = " ORDER BY [ID] DESC";
        }
        else {
            order1 = " ORDER BY [ID] DESC";
            order2 = " ORDER BY [ID]";
        }

        if (page == 1) {
            sql = "SELECT TOP " + pagesize + " [ID]" + fields + " FROM " + table +
                strCondition + order1;
        }
        else if (page == pagecount) {
            /*
            顺序：
            SELECT ... FROM (table) WHERE [ID] IN
            (SELECT TOP rest [ID] FROM (table) ORDER BY [ID] DESC)
            ORDER BY [ID]
            */
            int rest;   // 最后一页记录数
            rest = recordcount % pagesize;
            if (rest == 0)  rest = pagesize;
            sql =
                "SELECT [ID]" + fields + " FROM " + table + " WHERE [ID] IN " +
                "(SELECT TOP " + rest + " [ID] FROM " + table + order2 + ") " +
                order1;
        }
        else {
            /*
            顺序：
            SELECT ... FROM (table) WHERE [ID] IN
            (SELECT TOP (pagesize) [ID] FROM (table) WHERE [ID] IN
            (SELECT TOP (pagesize * page) [ID] FROM (table) WHERE (condition) ORDER BY [ID])
            ORDER BY [ID] DESC)
            ORDER BY [ID]
            反序：
            SELECT ... FROM (table) WHERE ID IN
            (SELECT TOP (pagesize) ID FROM (table) WHERE ID IN
            (SELECT TOP (pagesize * page) ID FROM (table) ORDER BY ID DESC)
            ORDER BY ID)
            ORDER BY ID DESC
            */
            sql =
                "SELECT [ID]" + fields + " FROM " + table + " WHERE [ID] IN " +
                "(SELECT TOP " + pagesize + " [ID] FROM " + table + " WHERE [ID] IN " +
                "(SELECT TOP " + (pagesize * page) + " [ID] FROM " + table +
                strCondition  + order1 + ")" + order2 + ")" + order1;
        }

        return sql;
    }
    public String getSql(String table) {
        this.table = table;
        return getSql();
    }
    public String getSql(int page) {
        this.page = page;
        return getSql();
    }
    public String getSql(String table, int page) {
        this.table = table;
        this.page = page;
        return getSql();
    }
    public String getSql(String table, String condition) {
        this.table = table;
        this.condition = condition;
        return getSql();
    }
    public String getSql(String table, String condition, int page) {
        this.table = table;
        this.condition = condition;
        this.page = page;
        return getSql();
    }

    public void setTable(String newTable) {
        table = newTable;
    }
    public String getTable() {
        return table;
    }
    public int getRecordcount() {
        return recordcount;
    }
    public void setPagesize(int newPagesize) {
        pagesize = newPagesize;
    }
    public int getPagesize() {
        return pagesize;
    }
    public int getPagecount() {
        return pagecount;
    }
    public void setPage(int newPage) {
        page = newPage;
    }
    public int getPage() {
        return page;
    }
    public void setCondition(String newCondition) {
        condition = newCondition;
    }
    public String getCondition() {
        return condition;
    }
    public void setStmt(Statement newStmt) {
        stmt = newStmt;
    }
    public Statement getStmt() {
        return stmt;
    }
    public void setFields(String newFields) {
        fields = newFields;
    }
    public void setFields(String[] newFields) {
        fields = "";
        for (int i = 0; i < newFields.length; i++) {
            fields += "," + newFields[i];
        }
    }
    public String getFields() {
        return fields;
    }
    public void setDirection(boolean newDirection) {
        direction = newDirection;
    }
    public boolean isDirection() {
        return direction;
    }
}