jdbc 使用properties導入資料庫資訊2

使用：props.load(DBUtils.class.getClassLoader().getResourceAsStream("day01/db.properties"));

導入配置檔案

使用的是反射機制

.class   ///獲得Class對象

.class.getClassLoader()   ///獲得ClassLoader對象

.class.getClassLoader().getResourceAsStream(String name);  //獲得inputStream對象

是以括号裡是inputStream對象  這肯定是不變的

///DBUtils.java

package day02;

import java.io.File;

import java.io.FileInputStream;

import java.sql.Connection;

import java.sql.DriverManager;

import java.util.Properties;

public class DBUtils {

private static String driver;

private static String url;

private static String user;

private static String password;

static{

try{

Properties props = new Properties();

//從類路徑中加載檔案

props.load(DBUtils.class.getClassLoader().getResourceAsStream("day01/db.properties"));

//props.load(new FileInputStream("db.properties"));

driver = props.getProperty("driver");

url = props.getProperty("url");

user = props.getProperty("user");

password = props.getProperty("password");

System.out.println(driver);

System.out.println(url);

System.out.println(user);

Class.forName(driver);

}catch(Exception e){

throw new RuntimeException(e);

}

public static Connection openConnection() throws Exception{         //靜态方法獲得連接配接

Connection con = DriverManager.getConnection(url,user,password);

return con;