jdbc to mysql 示例(1)續-優化

新建如下2個.java文件

package cn.dzj.demo.jdbc;

import java.sql.*;

/**
 * Create Date:2013-6-24 Author : Dzj E-mail : [email protected]
 */
public class BaseBetter {

	public static void main(String[] args) throws ClassNotFoundException {
		// TODO Auto-generated method stub
		try {
			jdbcTemplate();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	public static void jdbcTemplate() throws Exception {
		Connection conn = null;
		Statement stm = null;
		ResultSet rs = null;

		try {
			// build connection
			conn = JdbcUtils.getConnection();

			// create statement
			stm = conn.createStatement();

			// execute SQL
			rs = stm.executeQuery("Select * from persons;");

			// while get
			while (rs.next()) {
				System.out.println(rs.getObject(1) + "," + rs.getObject(2));
			}

		} finally {
			JdbcUtils.free(conn, stm, rs);
		}
	}
}

package cn.dzj.demo.jdbc;

import java.sql.*;

/**
 * Create Date:2013-6-24 Author : Dzj E-mail : [email protected]
 */
public final class JdbcUtils {
	public static String url = "jdbc:mysql://localhost:3306/PIMS";
	public static String username = "root";
	public static String password = "123456";
	public static String drivername = "com.mysql.jdbc.Driver";

	static {
		try {
			Class.forName(drivername);
		} catch (ClassNotFoundException e) {
			throw new ExceptionInInitializerError(e);
		}
	}

	public static Connection getConnection() throws SQLException {
		return DriverManager.getConnection(url, username, password);
	}

	public static void free(Connection conn, Statement st, ResultSet rs) {
		try {
			if (rs != null) {
				rs.close();
			}
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			try {
				if (st != null) {
					st.close();
				}
			} catch (SQLException e) {
				e.printStackTrace();
			} finally {
				try {
					if (conn != null) {
						conn.close();
					}
				} catch (SQLException e) {
					e.printStackTrace();
				}
			}
		}
	}
}