将连接数据库的JDBC提成BaseDao

package com.shangke;

import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

/**
 * 用来操纵数据库的类
 */
public class BeseDao {
    private static String url ="";
    private static String user ="";
    private static String password ="";
    private static String driver ="";
    private Connection conn = null;//数据库连接对象 connection
    PreparedStatement ps =null;//执行Sql statement对象
    ResultSet rs=null;//结果集
//因为只需加载一次所以就是用static代码块就可以了
    static{
        Properties pro=new Properties();
//获取读src下的输入流
        InputStream resourceStream = BeseDao.class.getClassLoader().getResourceAsStream("JDBC.properties");
        try {
//加载输入流
            pro.load(resourceStream );
//读取文件的key值
             url = pro.getProperty("url");
             user = pro.getProperty("user");
             password = pro.getProperty("password");
             driver = pro.getProperty("driver");
//加载驱动
            Class.forName(driver);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } finally {
//关闭流
            if(resourceStream!=null){
                try {
                    resourceStream .close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    //获取数据库连接
    public boolean getConnection(){
        try {
//将连接对象赋值
             conn = DriverManager.getConnection(url, user, password);
        } catch (SQLException e) {
            e.printStackTrace();
            return false;
        }
        return true;

    }

    //数据库增删改
    public int updataSQL(String sql,Object[]... obj) {
        int indenx =-1;
//先获取到连接对象
        if(this.getConnection()){
            try {
//使用连接对象 获取statement对象
                 ps = conn.prepareStatement(sql);
                 //填充占位符
                for(int i=0;i<obj.length;i++){
                    ps.setObject(i+1,obj[i]);
                }
                indenx = ps.executeUpdate();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return indenx;
    }
    //数据库查询
    public ResultSet querySQL(String sql, Object[]... obj) {
        if(this.getConnection()){
            try {
                ps=conn.prepareStatement(sql);
                //填充占位符
                for(int i=0;i<obj.length;i++){
                    ps.setObject(i+1,obj[i]);
                }
                 rs = ps.executeQuery();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

        return rs;
    }
    //释放资源
    public void close(){
        if(rs!=null){
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(ps!=null){
            try {
                ps.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(conn!=null){
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}