转: 数据库连接的工具类

package jdbc.util;
 
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;
 
public class DBUtil {
     
    private static String driver;
    private static String url;
    private static String username;
    private static String password;
     
    static{
        try{
        //读取配置文件，初始化数据连接参数
        String file = "/jdbc/util/db.properties";
        Properties map = new Properties();
        //从包中打开文件流
        InputStream in = DBUtil.class.getResourceAsStream(file);
        map.load(in); //自动将流读取到load中
        System.out.println(map);
        in.close();
        //读取文件的内容，初始化连接参数
        driver = map.getProperty("driver");
        url = map.getProperty("url");
        username = map.getProperty("username");
        password = map.getProperty("password");
        }catch(IOException e){
            e.printStackTrace();
            throw new RuntimeException(e);
        }
    }
 
    /** 数据库的管理方法 */
    public static Connection getConnection(){
        try{
        Class.forName(driver);
        Connection conn = DriverManager.getConnection(url,username,password);
        return conn;
        }catch(Exception e){
            e.printStackTrace();
            throw new RuntimeException("反正是没连上",e);
        }
    }
     
    /** 在DBUtil 类体中添加方法，方便关闭方法的重用*/
    public static void close(Connection conn){
        if(conn!=null){
            try {
                conn.close();
            } catch (SQLException e) {                  
                e.printStackTrace();
            }
        }
    }
 
}