java 连接超时。为什么？
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Connection timed out. Why?
提问by Psl
I get an exception when I run this code. Why?
运行此代码时出现异常。为什么？
Exception in thread "main" java.net.ConnectException: Connection timed out: connect
线程“main”中的异常java.net.ConnectException：连接超时：连接
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();
}
}
Exception:
例外：
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)
回答by Stephen C
Things you should look at:
你应该看的东西：
- can you
pingthe host? - can you connect to
http://www.verisign.comusing a web browser? - can you connect to
https://www.verisign.comusing a web browser? - can you connect to
http://www.verisign.comusing your program? - can you connect to anythingusing your program?
- 你能做
ping主人吗？ - 您可以
http://www.verisign.com使用网络浏览器连接吗？ - 您可以
https://www.verisign.com使用网络浏览器连接吗？ - 你能连接到
http://www.verisign.com使用你的程序吗？ - 你能用你的程序连接到任何东西吗？
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.
您的问题很可能与防火墙有关。我的第一个猜测是，您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发送 HTTP/HTTPS 请求。
