通用分页（一）

核心思路：将上一次 的查询请求再发送一次，这一次改变页码

PageBean 

private int page;  页数

private int rows;   行数

private boolean pagination； 是否分页

private int total; 总行数；

package com.page;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.List;

import com.dao.impl.BaseDao;

public class PageDao<E> extends BaseDao {
	public List<Boolean> executeQueryPage(String sql, PageBean pageBean, ICallBack<E> iCallBack) {
		Connection con = null;
		PreparedStatement ps = null;
		ResultSet rs = null;
		try {
			// 得到sql的总行数
			con = getcon();
			ps = con.prepareStatement(sql);
			rs = ps.executeQuery();
			pageBean.setTotal(rs.getString(1));
			close(ps, rs);
			// 调用分页sql语句
			ps = con.prepareStatement(getPageSql(sql, pageBean));
			rs = ps.executeQuery();
			return (List<Boolean>) iCallBack.forEach(rs);
		} catch (Exception e) {
			throw new RuntimeException(e);
		} finally {
			close(con, ps, rs);
		}

	}

	/**
	 * 返回总行数
	 * 
	 * @param sql
	 * @return
	 */
	private String getCountSql(String sql) {
		return "select count (*) from (" + sql + ") t1";
	}

	/**
	 * 返回分页语句
	 * 
	 * @param sql
	 * @param pageBean
	 * @return
	 */
	private String getPageSql(String sql, PageBean pageBean) {
		int page = pageBean.getPage();
		int rows = pageBean.getRows();
		return sql + "limit" + (page - 1) * rows + "." + rows;
	}
}

　　

package com.dao.impl;

import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.Properties;

/**
 * 连接数据库操作基本类
 * 
 * @author xyls
 *
 */

public class BaseDao {

    private static Properties properties = null;
    static {
        if (properties == null) {
            InputStream is = BaseDao.class.getResourceAsStream("/config.properties");
            properties = new Properties();
            try {
                properties.load(is);
                Class.forName(properties.getProperty("driver"));
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
        }
    }

    /**
     * 获取数据库连接对象
     * 
     * @return
     */
    public Connection getcon() {
        try {
            return DriverManager.getConnection(properties.getProperty("url"), properties.getProperty("user"),
                    properties.getProperty("pwd"));

        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * 关闭数据库的连接
     * 
     * @param con
     * @param ps
     */
    public void close(Connection con, PreparedStatement ps) {
        close(con, ps, null);
    }

    /**
     * 关闭数据库的连接
     * 
     * @param con
     * @param ps
     */
    public void close(PreparedStatement ps, ResultSet rs) {
        close(null, ps, rs);
    }

    /**
     * 关闭数据库的连接
     * 
     * @param con
     * @param ps
     * @param rs
     */
    public void close(Connection con, PreparedStatement ps, ResultSet rs) {
        try {
            if (rs != null) {
                rs.close();
            }
            if (ps != null) {
                ps.close();
            }
            if (con != null) {
                con.close();
            }
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    public int a(String sql, Object... objects) {
        Connection con = null;
        PreparedStatement ps = null;
        try {
            con = getcon();
            ps = con.prepareStatement(sql);
            for (int i = 0; i < objects.length; i++) {
                if (objects[i] != null) {
                    ps.setObject((i + 1), objects[i]);
                }
            }
            return ps.executeUpdate();
        } catch (Exception e) {
            throw new RuntimeException(e);
        } finally {
            close(con, ps);
        }
    }
}

package com.page;

/**
 * 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 + "]";
    }

}

package com.dao.impl;

import java.sql.ResultSet;
import java.util.ArrayList;
import java.util.List;

import com.dao.IBookDao;
import com.entity.BookBean;
import com.page.ICallBack;
import com.page.PageBean;
import com.page.PageDao;

public class BookDaoImpl extends PageDao<BookBean> implements IBookDao {

    @Override
    public List<Boolean> findBookListByBookNamePage(PageBean pageBean, BookBean Bean) {
        StringBuffer sb=new StringBuffer();
        sb.append("select * from t_book");
        if (Bean.getBookName().length()>0) {
            sb.append(" where bookname like '%"+Bean.getBookName()+"%'");
        }
        return executeQueryPage(sb.toString(), pageBean, new ICallBack<BookBean>() {
            List<BookBean> booklist=new ArrayList<>();
            @Override
            public List<BookBean> forEach(ResultSet rs) throws Exception {
                while(rs.next()) {
                    BookBean b=new BookBean();
                    b.setId(rs.getInt("id"));
                    b.setBookName(rs.getString("bookname"));
                    b.setPrice(rs.getDouble("price"));
                    b.setBooktype(rs.getInt("booktype"));
                    b.setCreateDate(rs.getDate("createdate"));
                    booklist.add(b);
                }
                return booklist;
                
            }
        });
    }

    @Override
    public int add(BookBean bookBean) {
        // TODO Auto-generated method stub
        return executeQueryPage(sql, pageBean, iCallBack)
    }

}