jdbc自制工具类: DBUtils, 减少代码重复

1. jdbcInfos.properties表(存放mysql数据库驱动和用户信息):

2. DBUtils工具类实现:

1. 调用getConn()方法时加载静态代码块 ,
完成注册驱动, 登录数据库, 并返回一个Connection对象
2. close()方法利用方法重载机制, 实现将jabc各个对象关闭的操作

package com.ujn.jdbcUtils;

import java.io.FileReader;
import java.net.URL;
import java.sql.*;
import java.util.Properties;

public class DBUtils {

    private static String url;
    private static String user;
    private static String password;
    private static String driver;

    /**
     * 调用静态方法时加载静态代码块
     */
    static {
        try {
            Properties ppts = new Properties();
            ClassLoader clr = DBUtils.class.getClassLoader();//clr类加载器对象
            URL res = clr.getResource("jdbcInfos.properties");
            String path = res.getPath();
            //System.out.println(path);
            ppts.load(new FileReader(path));//加载文件
            url = ppts.getProperty("url_test_database");
            user = ppts.getProperty("user");
            password = ppts.getProperty("password");
            driver = ppts.getProperty("driver");
            Class.forName(driver);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 获取数据库连接对象
     * @return Connection对象
     * @throws Exception
     */
    public static Connection getConn() throws Exception{
        return DriverManager.getConnection(url, user, password);
    }

    /**
     * 关闭数据库对象资源
     * @param stat Statement对象
     * @param conn Connection对象
     */
    public static void close(Statement stat, Connection conn){
        if (stat != null){
            try {
                stat.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (conn != null){
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 关闭数据库对象资源
     * @param res ResultSet对象
     * @param stat Statement对象
     * @param conn Connection对象
     */
    public static void close(ResultSet res, Statement stat, Connection conn){
        if (res != null){
            try {
                res.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (stat != null){
            try {
                stat.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (conn != null){
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 关闭数据库对象资源
     * @param res ResultSet对象
     * @param pstat PreparedStatement对象
     * @param conn Connection对象
     */
    public static void close(ResultSet res, PreparedStatement pstat, Connection conn){
        if (res != null){
            try {
                res.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (pstat != null){
            try {
                pstat.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (conn != null){
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 关闭数据库对象资源
     * @param pstat PreparedStatement对象
     * @param conn Connection对象
     */
    public static void close(PreparedStatement pstat, Connection conn){
        if (pstat != null){
            try {
                pstat.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (conn != null){
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

}