线程“main”中的异常 java.net.UnknownHostException：repo.maven.apache.org

Question

我是 spring 框架的新生。我从 start.spring.io 生成项目，现在尝试运行它。当我尝试时，我必须面对以下异常，（我使用 TomCat 服务器）请给出解决方案，

===========================异常====================== =======

G:\courses\Course-projects\spring-projects\S5Guru\spring5webapp>mvnw spring-boot:run
Exception in thread "main" java.net.UnknownHostException: repo.maven.apache.org
        at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:184)
        at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
        at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
        at java.net.Socket.connect(Socket.java:589)
        at sun.security.ssl.SSLSocketImpl.connect(SSLSocketImpl.java:668)
        at sun.security.ssl.BaseSSLSocketImpl.connect(BaseSSLSocketImpl.java:173)
        at sun.net.NetworkClient.doConnect(NetworkClient.java:180)
        at sun.net.www.http.HttpClient.openServer(HttpClient.java:432)
        at sun.net.www.http.HttpClient.openServer(HttpClient.java:527)
        at sun.net.www.protocol.https.HttpsClient.<init>(HttpsClient.java:264)
        at sun.net.www.protocol.https.HttpsClient.New(HttpsClient.java:367)
        at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(AbstractDelegateHttpsURLConnection.java:191)
        at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1138)
        at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1032)
        at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:177)
        at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1546)
        at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1474)
        at sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:254)
        at org.apache.maven.wrapper.DefaultDownloader.downloadInternal(DefaultDownloader.java:90)
        at org.apache.maven.wrapper.DefaultDownloader.download(DefaultDownloader.java:76)
        at org.apache.maven.wrapper.Installer.createDist(Installer.java:72)
        at org.apache.maven.wrapper.WrapperExecutor.execute(WrapperExecutor.java:121)
        at org.apache.maven.wrapper.MavenWrapperMain.main(MavenWrapperMain.java:61)

Answer 1

当存在代理服务器时（例如在公司网络中），就会出现此问题。要解决此问题，请使用以下内容创建文件 HOME/.mvn/jvm.config：

-Dhttp.proxyHost=<proxy-server>
-Dhttp.proxyPort=8080
-Dhttp.proxyUser=<user>
-Dhttp.proxyPassword=<password>
-Dhttps.proxyHost=<proxy-server>
-Dhttps.proxyPort=8080
-Dhttps.proxyUser=<user>
-Dhttps.proxyPassword=<password>