连接超时。为什么？ [英] Connection timed out. Why?

问题描述

运行此代码时出现异常。为什么？

I get an exception when I run this code. Why?

线程中的异常mainjava.net.ConnectException：连接超时：connect

Exception in thread "main" java.net.ConnectException: Connection timed out: connect

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.URL;

public class MainClass {

  public static void main(String[] args) throws Exception {
    System.setProperty("java.protocol.handler.pkgs", "com.sun.net.ssl.internal.www.protocol");

    URL url = new URL("https://www.verisign.com/");
    BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));

    String line;
    while ((line = in.readLine()) != null) {
      System.out.println(line);
    }
    in.close();
  }
}

异常：

Exception in thread "main" java.net.ConnectException: Connection timed out: connect
    at java.net.PlainSocketImpl.socketConnect(Native Method)
    at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
    at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
    at java.net.Socket.connect(Socket.java:525)
    at com.sun.net.ssl.internal.ssl.SSLSocketImpl.connect(SSLSocketImpl.java:550)
    at com.sun.net.ssl.internal.ssl.BaseSSLSocketImpl.connect(BaseSSLSocketImpl.java:141)
    at sun.net.NetworkClient.doConnect(NetworkClient.java:163)
    at sun.net.www.http.HttpClient.openServer(HttpClient.java:394)
    at sun.net.www.http.HttpClient.openServer(HttpClient.java:529)
    at sun.net.www.protocol.https.HttpsClient.<init>(HttpsClient.java:272)
    at sun.net.www.protocol.https.HttpsClient.New(HttpsClient.java:329)
    at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(AbstractDelegateHttpsURLConnection.java:172)
    at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:801)
    at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:158)
    at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1049)
    at com.sun.net.ssl.internal.www.protocol.https.HttpsURLConnectionOldImpl.getInputStream(HttpsURLConnectionOldImpl.java:204)
    at java.net.URL.openStream(URL.java:1010)
    at https.ssl.MainClass.main(MainClass.java:13)

推荐答案

你应该看看的东西：

• 你可以 ping 主持人？


• 您可以使用网络浏览器连接到 http://www.verisign.com 吗？


• 您可以使用网络浏览器连接到 https://www.verisign.com 吗？


• 可以连接吗？到 http://www.verisign.com 使用你的程序？


• 你可以连接到任何东西使用你的程序？

• can you ping the host?
• can you connect to http://www.verisign.com using a web browser?
• can you connect to https://www.verisign.com using a web browser?
• can you connect to http://www.verisign.com using your program?
• can you connect to anything using your program?

您的问题可能与防火墙有关。我的第一个猜测是你没有设置正确的环境变量或Java系统属性来告诉JVM使用本地代理服务器来传出HTTP / HTTPS请求。

The chances are that your problem is firewall related. My first guess would be that you don't have the correct environment variables or Java system properties set to tell the JVM to use a local proxy server for outgoing HTTP / HTTPS requests.

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