java中getResource()关于空指针的问题

Question

代码如下:

Properties prop = new Properties();

          ClassLoader cl = Demo.class.getClassLoader();
        URL res = cl.getResource("test.properties");
        String path = res.getPath();

        try {
            prop.load(new FileReader(path));
        } catch (IOException e) {
            e.printStackTrace();
        }
        String url = prop.getProperty("url");
        String user = prop.getProperty("user");
        String password = prop.getProperty("password");

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

        Statement state = connect.createStatement();

        ResultSet resultSet = state.executeQuery("select * from emp");

        while(resultSet.next()){
            int id = resultSet.getInt(1);
            System.out.println(id);
        }

        state.close();
        connect.close();

test.properties如果放在src外面和src同级，则会在String path = res.getPath();报错NullPointerException
test.properties如果放在src内，则会有如下报错：
java.io.FileNotFoundException: D:\1.%e5%9e%83%e5%9c%be%e7%ab%99\JAVAWEB\JDBC\out\production\JDBC\test.properties (系统找不到指定的路径。)
at java.base/java.io.FileInputStream.open0(Native Method)
at java.base/java.io.FileInputStream.open(FileInputStream.java:219)
at java.base/java.io.FileInputStream.(FileInputStream.java:157)
at java.base/java.io.FileInputStream.(FileInputStream.java:112)
at java.base/java.io.FileReader.(FileReader.java:60)
at DQL查询练习2.Demo.main(Demo.java:59)
Exception in thread "main" java.sql.SQLException: The url cannot be null
at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:660)
at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:228)
at DQL查询练习2.Demo.main(Demo.java:67)

67行是：Connection connect = DriverManager.getConnection(url, user, password);
59行是：prop.load(new FileReader(path));
我本想用getResource("")获取项目路径的再通过+"\src\test.properties"组合的,结果这条路好像行不通

Answer 1

空指针是由于没有获取到参数导致的。
很明显的报错The url cannot be null
建议找一篇Property的文档好好看一看。