web常用的工具类总结

数据库的链接的操作类

package utils;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

public class DBConnection {
    private static final String DBDRIVER = "com.mysql.jdbc.Driver" ;            //驱动类类名
    private static final String DBURL = "jdbc:mysql://localhost:3306/db_votemanage";//连接URL
    private static final String DBUSER = "root" ;                                //数据库用户名
    private static final String DBPASSWORD = "root";                            //数据库密码
    public static Connection getConnection(){
        Connection conn = null;                                                    //声明一个连接对象
        try {
            Class.forName(DBDRIVER);                                            //注册驱动
            conn = DriverManager.getConnection(DBURL,DBUSER,DBPASSWORD);        //获得连接对象
        } catch (ClassNotFoundException e) {                                    //捕获驱动类无法找到异常
            e.printStackTrace();
        } catch (SQLException e) {                                                //捕获SQL异常
            e.printStackTrace();
        }
        return conn;
    }
    public static void close(Connection conn) {//关闭连接对象
        if(conn != null) {                //如果conn连接对象不为空
            try {
                conn.close();            //关闭conn连接对象对象
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
    public static void close(PreparedStatement pstmt) {//关闭预处理对象
        if(pstmt != null) {                //如果pstmt预处理对象不为空
            try {
                pstmt.close();            //关闭pstmt预处理对象
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
    public static void close(ResultSet rs) {//关闭结果集对象
        if(rs != null) {                //如果rs结果集对象不为null
            try {
                rs.close();                //关闭rs结果集对象
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

分页的工具类

package utils;
public class Page {
    private int everyPage;            //每页显示记录数
    private int totalCount;            //总记录数
    private int totalPage;            //总页数
    private int currentPage;        //当前页
    private int beginIndex;            //查询起始点
    private boolean hasPrePage;        //是否有上一页
    private boolean hasNextPage;    //是否有下一页
    public Page(int everyPage, int totalCount, int totalPage,
            int currentPage,int beginIndex, boolean hasPrePage,
            boolean hasNextPage) {    //自定义构造方法
        this.everyPage = everyPage;
        this.totalCount = totalCount;
        this.totalPage = totalPage;
        this.currentPage = currentPage;
        this.beginIndex = beginIndex;
        this.hasPrePage = hasPrePage;
        this.hasNextPage = hasNextPage;
    }
    public Page(){}                    //默认构造函数
    public int getEveryPage() {        //获得每页显示记录数
        return everyPage;
    }
    public void setEveryPage(int everyPage) {//设置每页显示记录数
        this.everyPage = everyPage;
    }
    public int getTotalCount() {//获得总记录数
        return totalCount;
    }
    public void setTotalCount(int totalCount) {//设置总记录数
        this.totalCount = totalCount;
    }
    public int getTotalPage() {//获得总页数
        return totalPage;
    }
    public void setTotalPage(int totalPage) {//设置总页数
        this.totalPage = totalPage;
    }
    public int getCurrentPage() {//获得当前页
        return currentPage;
    }
    public void setCurrentPage(int currentPage) {//设置当前页
        this.currentPage = currentPage;
    }
    public int getBeginIndex() {//获得查询起始点
        return beginIndex;
    }
    public void setBeginIndex(int beginIndex) {//设置查询起始点
        this.beginIndex = beginIndex;
    }
    public boolean isHasPrePage() {//获得是否有上一页
        return hasPrePage;
    }
    public void setHasPrePage(boolean hasPrePage) {//设置是否有上一页
        this.hasPrePage = hasPrePage;
    }
    public boolean isHasNextPage() {//获得是否有下一页
        return hasNextPage;
    }
    public void setHasNextPage(boolean hasNextPage) {//设置是否有下一页
        this.hasNextPage = hasNextPage;
    }
}

-------------------------------------------------------------------------------

package utils;
/*
 * 分页信息辅助类
 */
public class PageUtil {
    public static Page createPage(int everyPage,int totalCount,int currentPage) {//创建分页信息对象
        everyPage = getEveryPage(everyPage);
        currentPage = getCurrentPage(currentPage);
        int totalPage = getTotalPage(everyPage, totalCount);
        int beginIndex = getBeginIndex(everyPage, currentPage);
        boolean hasPrePage = getHasPrePage(currentPage);
        boolean hasNextPage = getHasNextPage(totalPage, currentPage);
        return new Page(everyPage, totalCount, totalPage, currentPage,
                beginIndex, hasPrePage,  hasNextPage);
    }
    public static int getEveryPage(int everyPage) {        //获得每页显示记录数
        return everyPage == 0 ? 10 : everyPage;
    }
    public static int getCurrentPage(int currentPage) {    //获得当前页
        return currentPage == 0 ? 1 : currentPage;
    }
    public static int getTotalPage(int everyPage,int totalCount) {//获得总页数
        int totalPage = 0;
        if(totalCount != 0 &&totalCount % everyPage == 0) {
            totalPage = totalCount / everyPage;
        } else {
            totalPage = totalCount / everyPage + 1;
        }
        return totalPage;
    }
    public static int getBeginIndex(int everyPage,int currentPage) {//获得起始位置
        return (currentPage - 1) * everyPage;
    }
    public static boolean getHasPrePage(int currentPage) {//获得是否有上一页
        return currentPage == 1 ? false : true;
    }
    public static boolean getHasNextPage(int totalPage, int currentPage) {    //获得是否有上一页
        return currentPage == totalPage || totalPage == 0 ? false : true;
    }
}