BaseDao

package com.baiyun.dao;

import java.io.IOException;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.List;
import java.util.Properties;

public class BaseDao {
    private static String driver="";
    private static String url="";
    private static String id="";
    private static String pwd="";
    protected Connection cn=null;
    protected PreparedStatement pst=null;
    protected ResultSet rst=null;
    static{
        Properties ps=new Properties();
        try {
            ps.load(BaseDao.class.getResourceAsStream("/jdbc.properties"));
            driver=ps.getProperty("jdbc.driver");
            url=ps.getProperty("jdbc.url");
            id=ps.getProperty("jdbc.id");
            pwd=ps.getProperty("jdbc.pwd");
        } catch (IOException e) {
            e.printStackTrace();
        }
        try {
            Class.forName(driver);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
    //关闭数据库
    protected void close_db() throws SQLException{
        if(this.rst!=null){
            this.rst.close();
        }
        if(this.pst!=null){
            this.pst.close();
        }
        if(this.cn!=null){
            this.cn.close();
        }
    }
    //打开数据库，传入sql语句和参数，返回执行对象
    private PreparedStatement open_db(String sql,Object... param) throws SQLException{
        this.cn=DriverManager.getConnection(url, id, pwd);
        this.pst=this.cn.prepareStatement(sql);
        for(int i=0;i<param.length;i++){
            this.pst.setObject(i+1,param[i]);
        }
        return this.pst;
    }
    //增、删、改的执行结果
    private int update(PreparedStatement pt) throws SQLException{
        int count=0;
        count=pt.executeUpdate();
        this.close_db();
        return count;
    }
    //分页的数据总条数
    private int count(PreparedStatement pt) throws SQLException{
        int count=0;
        this.rst=pt.executeQuery();
        while(this.rst.next()){
            count=this.rst.getInt(1);
        }
        this.close_db();
        return count;
    }
    //分页查询
    private ResultSet query(PreparedStatement pt) throws SQLException{
        ResultSet rt=this.rst=pt.executeQuery();
        return rt;
    }
    protected int update(String sql,List param) throws SQLException{
        return this.update(sql, param.toArray());
    }
    protected int update(String sql,Object... param) throws SQLException{
        return this.update(this.open_db(sql, param));
    }
    protected int count(String sql,List param) throws SQLException{
        return this.count(sql, param.toArray());
    }
    protected int count(String sql,Object... param) throws SQLException{
        return this.count(this.open_db(sql, param));
    }
    protected ResultSet query(String sql,List param) throws SQLException{
        return this.query(sql, param.toArray());
    }
    protected ResultSet query(String sql,Object... param) throws SQLException{
        return this.query(this.open_db(sql, param));
    }
}