无法解析为类型

Question

我正在尝试在 JSP 代码中使用 HTTP 身份验证。但我收到 MyAuthenticator 无法解析为类型的错误。我在 jsp 页面中编写的代码的语法是否正确？任何建议将不胜感激..

    <%@ page language="java" import="java.net.Authenticator,java.net.PasswordAuthentication,java.io.BufferedReader,java.net.*,java.io.*" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<%

String urlToQuery = request.getParameter("url");
System.out.println(" " +urlToQuery);
//URL url = new URL(urlToQuery);



//InputStream in = conn.getInputStream();

String urlString = "";
String username = "";
String password = "";
Authenticator.setDefault(new MyAuthenticator(username, password));
URL url = new URL(urlToQuery);
URLConnection conn = url.openConnection();
InputStream content = (InputStream) url.getContent();
BufferedReader in = new BufferedReader(new InputStreamReader(content));
String line;
while ((line = in.readLine()) != null) {
  System.out.println(line);
}
System.out.println("Done.");

 class MyAuthenticator extends Authenticator {
    private String username, password;

    public MyAuthenticator(String user, String pass) {
      username = user;
      password = pass;
    }

    protected PasswordAuthentication getPasswordAuthentication() {
      System.out.println("Requesting Host  : " + getRequestingHost());
      System.out.println("Requesting Port  : " + getRequestingPort());
      System.out.println("Requesting Prompt : " + getRequestingPrompt());
      System.out.println("Requesting Protocol: " + getRequestingProtocol());
      System.out.println("Requesting Scheme : " + getRequestingScheme());
      System.out.println("Requesting Site  : " + getRequestingSite());
      return new PasswordAuthentication(username, password.toCharArray());
    }
  }



%>

<%=line %>

Answer 1

不要在 JSP 中定义内部类。将 JSP 视为一个简单的方法。

JSP 类似于（1）：

public class MyJSP extends Servlet {
  public void service(HttpRequest request, HttpResponse response) {
     /** JSP CODE HERE **/
  }
}

定义内部类应该作为匿名内部类完成：

 Authenticator.setDefault(new Authenticator() {
   protected getPasswordAuthentication() {
     System.out.println("Requesting Host  : " + getRequestingHost());
     System.out.println("Requesting Port  : " + getRequestingPort());
     ...
   }
 });

不确定我会做什么来传递参数（我只使用了最简单的匿名内部类）。

无论如何，对于将从外部方法使用的任何内容，我将使用公共类（在其自己的文件中）并避免所有这些麻烦。

(1)不完全是这样，但你明白了。

Answer 2

<% ... %> 使 JSP 将代码内容视为语句。因此，您的类成为局部类，遵循与局部变量相同的作用域规则（即，您必须在使用该类之前声明该类）。我没有测试它，但如果您将代码重写为：

    <%@ page language="java" import="java.net.Authenticator,java.net.PasswordAuthentication,java.io.BufferedReader,java.net.*,java.io.*" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<%

class MyAuthenticator extends Authenticator {
    private String username, password;

    public MyAuthenticator(String user, String pass) {
      username = user;
      password = pass;
    }

    protected PasswordAuthentication getPasswordAuthentication() {
      System.out.println("Requesting Host  : " + getRequestingHost());
      System.out.println("Requesting Port  : " + getRequestingPort());
      System.out.println("Requesting Prompt : " + getRequestingPrompt());
      System.out.println("Requesting Protocol: " + getRequestingProtocol());
      System.out.println("Requesting Scheme : " + getRequestingScheme());
      System.out.println("Requesting Site  : " + getRequestingSite());
      return new PasswordAuthentication(username, password.toCharArray());
    }
  }

String urlToQuery = request.getParameter("url");
System.out.println(" " +urlToQuery);
//URL url = new URL(urlToQuery);



//InputStream in = conn.getInputStream();

String urlString = "";
String username = "";
String password = "";
Authenticator.setDefault(new MyAuthenticator(username, password));
URL url = new URL(urlToQuery);
URLConnection conn = url.openConnection();
InputStream content = (InputStream) url.getContent();
BufferedReader in = new BufferedReader(new InputStreamReader(content));
String line;
while ((line = in.readLine()) != null) {
  System.out.println(line);
}
System.out.println("Done.");





%>

<%=line %>

那么 MyAuthenticator 应该可以在您的代码中解析。

考虑将 Java 类移至单独的文件以使代码更具可读性。