1. 使用java.util.Properties类的load()方法（注意点：jdbc.properties这个文件若以此种方式加载，必须要放在类路径下，不然将无法进行加载）

InputStream inputStream = new BufferedInputStream(new   FileInputStream(new File("jdbc.properties")));
        Properties properties =new Properties();
        properties.load(inputStream);
        System.out.println(properties.get("jdbc.url"));

        2. 使用java.util.ResourceBundle类的getBundle()方法（注意点：文件的写入并没有文件的后缀名）

ResourceBundle rb = ResourceBundle.getBundle("jdbc",Locale.getDefault());
            Enumeration<String> keys = rb.getKeys();
            while (keys.hasMoreElements()) {
                  String key = (String) keys.nextElement();
                  System.out.println(rb.getString(key));
           }

        3.  使用java.util.PropertyResourceBundle类的构造函数

InputStream inputStream = new BufferedInputStream(new FileInputStream("src/jdbc.properties"));
        ResourceBundle bundle =new PropertyResourceBundle(inputStream);
        System.out.println(bundle.getString("jdbc.url"));

       4. 使用java.lang.ClassLoader类的getSystemResourceAsStream()静态方法

InputStream inputStream = ClassLoader.getSystemResourceAsStream("jdbc.properties"); 
         Properties properties =new Properties();
         properties.load(inputStream);
         System.out.println(properties.get("jdbc.url"));

       5.  使用class.getClassLoader()所得到的java.lang.ClassLoader的getResourceAsStream()方法

InputStream inputStream = JDBCProperties.class.getClassLoader().getResourceAsStream("jdbc.properties");
         Properties properties =new Properties();
         properties.load(inputStream);
         System.out.println(properties.get("jdbc.url"));

       6.  使用java.lang.ClassLoader类的getSystemResourceAsStream()静态方法

InputStream inputStream = JDBCProperties.class.getResourceAsStream("/jdbc.properties");
         Properties properties =new Properties();
         properties.load(inputStream);
         System.out.println(properties.get("jdbc.url"));

      7. Servlet中可以使用javax.servlet.ServletContext的getResourceAsStream()方法

InputStream in = context.getResourceAsStream(path);
       Properties p = new Properties();
       p.load(in);