自写的mysqljdbc程序

连接mysql数据库：mydata

import java.sql.*;

public class TestMysqlConnection {

    /**
     * @param args
     */
    public static void main(String[] args) {
        Connection con=null;
        PreparedStatement pSta=null;
        ResultSet rs=null;
        con = DBManager.getConnection();
        String sql = "select * from dept";
        try {
            pSta = con.prepareStatement(sql);
            rs = pSta.executeQuery();
            while (rs.next()) {
                int depno = rs.getInt("depno");
                String dname = rs.getString("dname");
                String loc = rs.getString("loc");
                System.out.println(depno + "--" + dname + "--" + loc);
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally{
            DBManager.closeResultSet(rs);
            DBManager.closeStatement(pSta);
            DBManager.closeConnection(con);
        }
    }
}

class DBManager {
    public static Connection getConnection() {
        Connection con = null;
        
        try {
            Class.forName("com.mysql.jdbc.Driver");
            con = DriverManager
                    .getConnection("jdbc:mysql://localhost:3306/mydata?user=root&password=root");
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return con;
    }

    public static void closeResultSet(ResultSet rs) {
        try {
            if (rs != null) {
                rs.close();
                rs = null;
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    public static void closeStatement(PreparedStatement pSta) {
        try {
            if (pSta != null) {
                pSta.close();
                pSta = null;
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    public static void closeConnection(Connection con) {
        try {
            if (con != null && !con.isClosed()) {
                con.close();
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

}

PreparedStatement接口继承自Statement接口，PreparedStatement实例包含已编译的SQL语句，且SQL语句可以有输入参数。这些输入参数在SQL语句创建时并未被指定，而是为每个输入参
数保留一个问号作为占位符。在执行PreparedStatement对象之前，必须通过setXXX方法来设置每个输入参数的值。例如：
　　pSta.setInt(1,1);就是为第一个参数设置整型值1.
　　pSta.setString(2,"博客园");就是为第二个参数设置String类型值"博客园".