1.在mysql中创建supmark数据库 新建表main 插入数据

2.新建java项目。导入jar包，创建包，创建类

?

3.sqlHelper类（如下）

package com.sup.sqlhelper;

import java.sql.*;

public class sqlHelper {

public Connection getConn() {
Connection conn = null;
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
try {
conn = DriverManager.getConnection(
"jdbc:mysql://127.0.0.1:3306/supmark", "admin", "admin");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return conn;
}

public void closeAll(ResultSet rs, Statement stat, Connection conn) {
if (rs != null)
try {
rs.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
if (stat != null)
try {
stat.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
if (conn != null)
try {
conn.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

4.主程序main调用如下:

package com.sup.main;

import java.sql.*;

import com.sup.sqlhelper.sqlHelper;

public class supmain {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
sqlHelper sql=new sqlHelper();
Connection con=sql.getConn();
ResultSet rs=null;
Statement stmt=null;
try {
stmt= con.createStatement() ;
rs= stmt.executeQuery("SELECT * FROM main");
System.out.println("\t================================商品存货列表================================");
while (rs.next()) {
try {
String name = rs.getString("buessName");
String buyPrice = rs.getString("buyPrice");
String numHave = rs.getString("numHave");
String salePrice = rs.getString("salePrice");
System.out.print("\t商品名称:"+name);
System.out.print("\t商品买入价格:"+buyPrice+"元");
System.out.print("\t商品数量:"+numHave);
System.out.print("\t商品卖出价格:"+salePrice+"元");
System.out.println();
} catch (Exception e) {
System.out.println("\t数据库缺少指定列！请查询数据库是否正常!");
System.out.println("\t错误内容.."+e);
sql.closeAll(rs, stmt, con);
}
}
System.out.println("\t======================================================================");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
sql.closeAll(rs, stmt, con);
}
}

}

5.执行效果

================================商品存货列表================================
商品名称:康师傅绿茶(250ML) 商品买入价格:2.3元 商品数量:150 商品卖出价格:2.5元
商品名称:康师傅方便面(包) 商品买入价格:2.9元 商品数量:200 商品卖出价格:4元
商品名称:拿铁咖啡(250ML) 商品买入价格:2元 商品数量:400 商品卖出价格:3.5元
商品名称:雀巢咖啡(包) 商品买入价格:0.4元 商品数量:1000 商品卖出价格:1元
======================================================================

(注：该方法可能存在问题，欢迎提出修改)