J2EE 中的数据库连接类

1.DBConfig.properties

#属性文件，存放JDBC联接数据库的参数
#sql2005驱动
#DataBaseDriver = com.microsoft.sqlserver.jdbc.SQLServerDriver
#DataBaseURL = jdbc:sqlserver://localhost:1433;SelectMode=cursor;DatabaseName=drp
#DataBaseUser = sa
#DataBaseUserPassword = 

#mysql驱动
DataBaseDriver = com.mysql.jdbc.Driver
DataBaseURL = jdbc:mysql://localhost:3306/drp
DataBaseUser = root
DataBaseUserPassword = root

2.DBConnectionException.java

package com.mp.struts.util;

/**
 * 该异常类用来封装联接数据库时可能出现的异常
 * @author  穆 鹏
 *
 */
@SuppressWarnings("serial")
public class DBConnectionException extends Exception{
	public DBConnectionException(String message) {
		super(message);
	}
}

3.DBConnection.java

package com.mp.struts.util;
import java.io.InputStream;
import java.io.IOException;
import java.sql.*;
import java.util.Properties;

/**
 * 实用工具类,获得通过JDBC联接数据库的联接对象.
 * 联接数据库所需的参数放在资源属性文件DBConfig.properties中,
 * 该文件位于类路径的根目录下
 * @author 	穆	鹏
 *
 */
public class DBConnection {

	private static String CONFIG_FILENAME = "DBConfig.properties";
	private static String driverName = "";
	private static String url = "";
	private static String user = "";
	private static String password = "";


	/**
	 * 返回数据库联接
	 * 
	 * @return Connection
	 * @throws DBConnectionException 
	 * @throws SQLException 
	 * @throws SQLException
	 */
	public static Connection getConnection() throws DBConnectionException, SQLException {
		Properties prop = new Properties();

		// 读取配置文件信息
		InputStream in = DBConnection.class.getResourceAsStream("/"
				+ CONFIG_FILENAME);
		
		Connection conn = null;
		try {
			//装载属性文件
			prop.load(in);
			//从属性文件中读取JDBC联接数据库的参数
			driverName = prop.getProperty("DataBaseDriver");
			user = prop.getProperty("DataBaseUser");// 用户,口令
			password = prop.getProperty("DataBaseUserPassword");//口令
			url = prop.getProperty("DataBaseURL");// url
			// 装载驱动程序
			Class.forName(driverName);
			conn = DriverManager.getConnection(url, user, password);
		} catch (IOException e) {
			throw new DBConnectionException("装载数据库配置文件" + CONFIG_FILENAME
					+ "时错误!");
		} catch (ClassNotFoundException e) {
			throw new DBConnectionException("装载驱动程序" + driverName + "时错误!");
		}
		return conn;
	}
	
	/**
	 * 
	 * @param conn
	 * @throws SQLException
	 */
	public static void closeConn(Connection conn) throws SQLException {
		if(conn != null) {
			conn.close();
			conn = null;
		}
	}

	/**
	 * 
	 * @param stmt
	 * @throws SQLException
	 */
	public static void closeStmt(Statement stmt) throws SQLException {
		if(stmt != null) {
			stmt.close();
			stmt = null;
		}
	}
	
	/**
	 * 
	 * @param rs
	 * @throws SQLException
	 */
	public static void closeRs(ResultSet rs) throws SQLException {
		if(rs != null) {
			rs.close();
			rs = null;
		}
	}
	/**
	 * 测试主函数
	 * 如果未抛出异常则说明正确
	 * @param args
	 * @throws Exception
	 */
	public static void main(String[] args) throws Exception {
		
		Connection conn = DBConnection.getConnection();
		System.out.println("Connection -"+ conn.getCatalog() +" OK!");
		DBConnection.closeConn(conn);
		System.out.println("Connection is closed! now connection = " + conn.getCatalog());
	}
}