当我尝试更新Jenkins服务器中的插件时，就发生了这种情况。出现以下消息，我不知道从哪里开始。
java.net.MalformedURLException: no protocol: at java.net.URL.(URL.java:593) at java.net.URL.(URL.java:490) at java.net.URL.(URL.java:439) at
hudson.model.UpdateCenter$UpdateCenterConfiguration.toUpdateCenterCheckUrl(UpdateCenter.java:1067) at
hudson.model.UpdateCenter$UpdateCenterConfiguration.checkUpdateCenter(UpdateCenter.java:1053) at
hudson.model.UpdateCenter$ConnectionCheckJob.run(UpdateCenter.java:1488) at
java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) at
java.util.concurrent.FutureTask.run(FutureTask.java:266) at hudson.remoting.AtmostOneThreadExecutor$Worker.run(AtmostOneThreadExecutor.java:110) at java.lang.Thread.run(Thread.java:748)
以下是插件的详细信息
java.io.IOException: Server returned HTTP response code: 401 for URL: http://updates.jenkins-ci.org/download/plugins/pipeline-model-definition/1.1.8/pipeline-model-definition.hpi
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1876)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1474)
at sun.net.www.protocol.http.HttpURLConnection.getHeaderField(HttpURLConnection.java:2982)
at java.net.URLConnection.getHeaderFieldLong(URLConnection.java:629)
at java.net.URLConnection.getContentLengthLong(URLConnection.java:501)
at java.net.URLConnection.getContentLength(URLConnection.java:485)
at hudson.model.UpdateCenter$UpdateCenterConfiguration.download(UpdateCenter.java:1126)
Caused: java.io.IOException: Server returned HTTP response code: 401 for URL: http://updates.jenkins-ci.org/download/plugins/pipeline-model-definition/1.1.8/pipeline-model-definition.hpi
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at sun.net.www.protocol.http.HttpURLConnection$10.run(HttpURLConnection.java:1926)
at sun.net.www.protocol.http.HttpURLConnection$10.run(HttpURLConnection.java:1921)
at java.security.AccessController.doPrivileged(Native Method)
at sun.net.www.protocol.http.HttpURLConnection.getChainedException(HttpURLConnection.java:1920)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1490)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1474)
at hudson.model.UpdateCenter$UpdateCenterConfiguration.download(UpdateCenter.java:1139)
Caused: java.io.IOException: Failed to load http://updates.jenkins-ci.org/download/plugins/pipeline-model-definition/1.1.8/pipeline-model-definition.hpi to /var/lib/jenkins/plugins/pipeline-model-definition.jpi.tmp
at hudson.model.UpdateCenter$UpdateCenterConfiguration.download(UpdateCenter.java:1146)
Caused: hudson.util.IOException2: Failed to download from http://updates.jenkins-ci.org/download/plugins/pipeline-model-definition/1.1.8/pipeline-model-definition.hpi
at hudson.model.UpdateCenter$UpdateCenterConfiguration.download(UpdateCenter.java:1172)
at hudson.model.UpdateCenter$DownloadJob._run(UpdateCenter.java:1677)
at hudson.model.UpdateCenter$InstallationJob._run(UpdateCenter.java:1874)
at hudson.model.UpdateCenter$DownloadJob.run(UpdateCenter.java:1651)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at hudson.remoting.AtmostOneThreadExecutor$Worker.run(AtmostOneThreadExecutor.java:110)
at java.lang.Thread.run(Thread.java:748)
因此，似乎MalformedURLException是由未经授权访问插件下载URL引起的。我该如何解决这个问题呢？