jdbc DBUtils

package jing.lian.kui.util;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

import jing.lian.kui.common.Common;

public class DBUtil {
    private static Connection con = null;
    private Statement statement;
    private ResultSet resultSet;
    private static String userName;
    private static String password;
    private static String driver;
    private static String host;
    private static String databasename;
    private static String url;
    private static String port;
    private static Properties properties = null;
    private final static String pathName = Common.decode(DBUtil.class.getResource("/config.properties").getPath());
    static{
    	if(properties == null)
    		 properties = new Properties();
    	try {
			InputStream inputStream = new FileInputStream(pathName);
			properties.load(inputStream);
			inputStream.close();
			init();
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		}catch(IOException e){
			e.printStackTrace();
		}
    }
    
    public DBUtil() {
	}
    
    public static void init(){
      	databasename = properties.getProperty("databasename");
    	userName = properties.getProperty("userName");
    	password = properties.getProperty("password");
    	driver = properties.getProperty("driver");
    	host = properties.getProperty("host");
    	port = properties.getProperty("port");
    	url =properties.getProperty("url")+host+":"+port+"/"+databasename;
    }
    
    
    public synchronized static Connection getConnection(){
    	if(con==null){
    		try {
    			System.out.println(driver);
    			Class.forName(driver).newInstance();
    			con = DriverManager.getConnection(url, userName, password);
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    	}
    	return con;
    }
    
    
    
    public int update(String sql){
    	int i = 0;
    	con = getConnection();
    	try {
			this.statement = con.createStatement();
			i = statement.executeUpdate(sql);
		} catch (SQLException e) {
			e.printStackTrace();
			i = -1;
		}finally{
			this.close();
		}
    	return i;
    }
    
    
    
  
    
    public ResultSet queryDate(String sql) {
    	con = getConnection();
		try {
			this.statement = con.createStatement();
			this.resultSet = statement.executeQuery(sql);
		} catch (SQLException e) {
			e.printStackTrace();
		}finally{
			this.close();
		}
		return this.resultSet;
	}
    
    
    
	/**
	 * 释放数据库资源
	 */
	public void close() {
		try {
			if (resultSet != null) {
				resultSet.close();
				resultSet = null;
			}
			if (statement != null) {
				statement.close();
				statement = null;
			}
			if (con != null) {
				con.close();
				con = null;
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}
}

properties文件:放在class文件下

userName = root
password = 000000
driver = com.mysql.jdbc.Driver
databasename = test
host = 127.0.0.1
port = 3306
url = jdbc:mysql://