一定要注意配置文件放的位置 是在src文件下的第一层，不能放其他地方

package com.ryan.demo4jdbc;

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




public class JDBCUtils {
    private static Connection conn;
    private static String user;
    private static String password;
    private static String url;
    private static String driverClass;


    static{
        try{
            readConfig();
            Class.forName(driverClass);
            conn=  DriverManager.getConnection(url,user,password);
                       }catch (Exception ex){
            throw new RuntimeException("数据库连接失败");
        }

    }
    public static void readConfig() throws Exception{
        InputStream in=JDBCUtils.class.getClassLoader().getResourceAsStream("database.properties");
        Properties pro=new Properties();
        pro.load(in);
        driverClass=pro.getProperty("driverClass");
        url=pro.getProperty("url");
        password=pro.getProperty("password");
        user=pro.getProperty("user");
    }
   public static Connection getConnection(){
       return conn;
   }
    public static void close(Connection conn,PreparedStatement stat,ResultSet rs){
        if(rs!=null){
            try{rs.close();}catch (Exception ex){}
        }
        if(stat!=null){
            try{stat.close();}catch (Exception ex){}
        }if(conn!=null){
            try{conn.close();}catch (Exception ex){}
        }

    }
}

package com.ryan.demo4jdbc;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;
import com.mysql.jdbc.Driver;


public class JDBCUtilsDemo {

    public static void main(String[] args)throws  Exception{
      Connection conn= JDBCUtils.getConnection();
      System.out.println(conn);
        PreparedStatement pst=conn.prepareStatement("SELECT *FROM sort");
        ResultSet rs=pst.executeQuery();
        List<Sort> list=new ArrayList<Sort>();
       while (rs.next()){
           Sort s= new Sort(rs.getInt("sid"),rs.getString("sname"),rs.getDouble("sprice"),rs.getString("sdescr"));
               
       list.add(s);}
        JDBCUtils.close(conn, pst, rs);
        for(Sort s:list)
        {System.out.println(s);}

    }
}

/**
 * Created by Administrator on 2018/5/23.
 */
public class Sort {
    private Integer sid;
    private  String sname;
    private  Double sprice;
    private  String sdescr;

    public Sort(String sdescr, Double sprice, String sname, Integer sid) {
        this.sdescr = sdescr;
        this.sprice = sprice;
        this.sname = sname;
        this.sid = sid;
    }

    @Override
    public String toString() {
        return "Sort{" +
                "sid=" + sid +
                ", sname='" + sname + '\'' +
                ", sprice=" + sprice +
                ", sdescr='" + sdescr + '\'' +
                '}';
    }

    public String getSdescr() {
        return sdescr;
    }

    public void setSdescr(String sdescr) {
        this.sdescr = sdescr;
    }

    public Double getSprice() {
        return sprice;
    }

    public void setSprice(Double sprice) {
        this.sprice = sprice;
    }

    public String getSname() {
        return sname;
    }

    public void setSname(String sname) {
        this.sname = sname;
    }

    public Integer getSid() {
        return sid;
    }

    public void setSid(Integer sid) {
        this.sid = sid;
    }
}