java - 客户端或服务器上的 NoRouteToHostException？

Question

我得到了

Caused by: java.net.NoRouteToHostException: No route to host
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:351)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:213)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:200)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
at java.net.Socket.connect(Socket.java:529)
at com.sun.net.ssl.internal.ssl.SSLSocketImpl.connect(SSLSocketImpl.java:564)
at sun.reflect.GeneratedMethodAccessor638.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.commons.httpclient.protocol.ReflectionSocketFactory.createSocket(ReflectionSocketFactory.java:140)
at org.apache.commons.httpclient.protocol.SSLProtocolSocketFactory.createSocket(SSLProtocolSocketFactory.java:130)
at org.apache.commons.httpclient.HttpConnection.open(HttpConnection.java:707)
at org.apache.commons.httpclient.HttpMethodDirector.executeWithRetry(HttpMethodDirector.java:387)
at org.apache.commons.httpclient.HttpMethodDirector.executeMethod(HttpMethodDirector.java:171)
at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:397)
at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:323)

javadoc说

Signals that an error occurred while attempting to connect a socket to a remote address and port. Typically, the remote host cannot be reached because of an intervening firewall, or if an intermediate router is down.

这个错误是在客户端还是在远程，或者它可以是其中之一？

Answer 1

基本上它表示您的客户端无法连接到服务器，因为客户端计算机无法访问该地址。

请通过命令提示符 (Windows) 或终端(基于 Unix)中的 ping 命令检查您要连接的地址是否可访问:

ping <address>

或者如果它是一个网络服务器，您可以尝试在您的网络浏览器中检查它。
在大多数情况下，ping 命令对我很有帮助，因为我知道为什么我无法连接到该地址。它可能是输入错误的地址，或者如 javadoc 所建议的那样，是防火墙问题。