Java 连接超时。为什么？_Java

Java 连接超时。为什么？

java

Java 连接超时。为什么？,java,Java,当我运行此代码时，会出现异常。为什么? 线程“main”java.net.ConnectException中出现异常：连接超时：连接例外情况： Exception in thread "main" java.net.ConnectException: Connection timed out: connect at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.PlainSocketImpl.

当我运行此代码时，会出现异常。为什么?

线程“main”java.net.ConnectException中出现异常：连接超时：连接

例外情况：

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)

线程“main”java.net.ConnectException:连接超时：连接位于java.net.PlainSocketImpl.socketConnect（本机方法）位于java.net.PlainSocketImpl.doConnect（PlainSocketImpl.java:333）位于java.net.PlainSocketImpl.connectToAddress（PlainSocketImpl.java:195）位于java.net.PlainSocketImpl.connect（PlainSocketImpl.java:182）位于java.net.socksocketimpl.connect（socksocketimpl.java:366）位于java.net.Socket.connect（Socket.java:525）位于com.sun.net.ssl.internal.ssl.SSLSocketImpl.connect（SSLSocketImpl.java:550）位于com.sun.net.ssl.internal.ssl.BaseSSLSocketImpl.connect（BaseSSLSocketImpl.java:141）位于sun.net.NetworkClient.doConnect（NetworkClient.java:163）位于sun.net.www.http.HttpClient.openServer（HttpClient.java:394）位于sun.net.www.http.HttpClient.openServer（HttpClient.java:529）在sun.net.www.protocol.https.HttpsClient.（HttpsClient.java:272）位于sun.net.www.protocol.https.HttpsClient.New（HttpsClient.java:329）位于sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient（AbstractDelegateHttpsURLConnection.java:172）位于sun.net.www.protocol.http.HttpURLConnection.plainConnect（HttpURLConnection.java:801）位于sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect（AbstractDelegateHttpsURLConnection.java:158）位于sun.net.www.protocol.http.HttpURLConnection.getInputStream（HttpURLConnection.java:1049）位于com.sun.net.ssl.internal.www.protocol.https.HttpsURLConnectionOldImpl.getInputStream（HttpsURLConnectionOldImpl.java:204）位于java.net.URL.openStream（URL.java:1010）位于https.ssl.MainClass.main（MainClass.java:13）

你应该看的东西：

你能
```
ping
```
主机吗
你能连接到
```
http://www.verisign.com
```
是否使用web浏览器
你能连接到
```
https://www.verisign.com
```
是否使用web浏览器
你能连接到
```
http://www.verisign.com
```
是否使用您的程序
你能用你的程序连接到任何东西吗

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来发送HTTP/HTTPS请求。

那么您以前自己采取了哪些步骤来解决这个问题呢？我认为您的连接超时了。对我来说，这就是它的样子。只需ping一下站点，看看你是否可以连接，或者连接需要花费很多时间。

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)