java - 从 URL 读取文件时出现问题 - 权限被拒绝

Question

我试图连接到这样的主机

                url = new URL(urlString);
                BufferedReader in = new BufferedReader(
                                new InputStreamReader(
                                url.openStream()));

但我总是得到 MalformedException - 权限被拒绝，我需要提供用户名和密码(我知道)，但我不知道如何提供，URL 中没有带有这些参数的构造函数，也没有 setusername/password 方法。用户名和密码放在哪里？

Answer 1

我在之前的项目中曾这样做过。为了访问 protected 资源，您需要使用 Authenticator 类。

用户名和密码进入最后为它们定义的变量中，但它们不必硬编码，您可以使用 java 属性将它们外部化。

这是一个旧的片段

// Install the custom authenticator
Authenticator.setDefault(new MyAuthenticator());

// Access the page
try {
    // Create a URL for the desired page
    URL url = new URL("THE URL YOU NEED TO OPEN/ACCESS");

    // Read all the text returned by the server
    BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));
    String str;
    while ((str = in.readLine()) != null) {
        // str is one line of text; readLine() strips the newline character(s)
    }
    in.close();
} catch (MalformedURLException e) {
} catch (IOException e) {
}

public class MyAuthenticator extends Authenticator {
    // This method is called when a password-protected URL is accessed
    protected PasswordAuthentication getPasswordAuthentication() {
        // Get information about the request
        String promptString = getRequestingPrompt();
        String hostname = getRequestingHost();
        InetAddress ipaddr = getRequestingSite();
        int port = getRequestingPort();

        // Get the username from the user...
        String username = "myusername";

        // Get the password from the user...
        String password = "mypassword";

        // Return the information
        return new PasswordAuthentication(username, password.toCharArray());
    }
}