【JAVA】异常记录：java.net.ConnectException: Connection refused: connect

今天在测试HTTPURLConnection时报了一个这样的错：

java.net.ConnectException: Connection refused: 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 java.net.Socket.connect(Socket.java:475)
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.http.HttpClient.<init>(HttpClient.java:233)
at sun.net.www.http.HttpClient.New(HttpClient.java:306)
at sun.net.www.http.HttpClient.New(HttpClient.java:323)
at sun.net.www.protocol.http.HttpURLConnection.getNewHttpClient(HttpURLConnection.java:860)
at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:801)
at sun.net.www.protocol.http.HttpURLConnection.connect(HttpURLConnection.java:726)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1049)
at java.net.URL.openStream(URL.java:1010)

经检查发现是端口号不对，我项目是8022，而我写成了8080；

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补充：以上情况出现在服务器正常运行的情况下，如果服务器没有开启，也会出现这种问题。

不光是端口不对，也可能ip地址啊，请求的服务不对啊，等等。。。。。。。。。。。。。。。。。。。。。。