我的POST请求在NullPointerException抛出一个getResponseCode()，然而，它一直运作到今天。等效的curl调用可以正常工作，所以问题应该是Java。相同的实现（当然没有一些属性）适用于GET请求。这里是：
private Object executeRequest(URL url, String httpMethod, String contentType, URL jobPropsPath)
throws NoSuchAlgorithmException, KeyManagementException,
MalformedURLException, IOException, ParseException {
if(contentType == null) {
contentType = "application/json";
}
// curl -k
TrustManager[] trustAllCerts = { new OozieWorkflowTest.CustomX509TrustManager() };
SSLContext sc = SSLContext.getInstance("SSL");
sc.init(null, trustAllCerts, new SecureRandom());
HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());
HostnameVerifier allHostsValid = (hostname, session) -> true;
HttpsURLConnection.setDefaultHostnameVerifier(allHostsValid);
// execute a request
HttpsURLConnection conn = (HttpsURLConnection) url.openConnection();
conn.setRequestProperty("Content-Type", contentType);
conn.setRequestMethod(httpMethod);
conn.setConnectTimeout(30000);
// prepare request body (for XML only)
if( (jobPropsPath != null) && ("POST".equals(httpMethod)) ) {
File jobPropsXml = new File(jobPropsPath.getPath());
if(jobPropsXml.exists()) {
String jobPropsSerialized = this.serializeXml(jobPropsXml);
conn.setDoOutput(true);
// Add serialized String to a request body
try(OutputStream output = new BufferedOutputStream(conn.getOutputStream())) {
output.write(jobPropsSerialized.getBytes());
output.flush();
}
} else {
throw new IOException("Requested file does not exist in specified path.");
}
}
// Process response
int status = conn.getResponseCode();
StringBuilder sb = new StringBuilder();
switch (status) {
...
}
conn.disconnect();
return new JSONParser().parse(sb.toString());
}
这是等效的卷曲调用（为了更清晰）
curl -i -k --negotiate -u : -X POST -H "Content-Type: application/xml" -d foo/bar/wf.xml "https://host:port/oozie/v1/jobs"
堆栈跟踪：
java.lang.RuntimeException: java.lang.NullPointerException
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1488)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1474)
at sun.net.www.protocol.http.HttpURLConnection.getHeaderField(HttpURLConnection.java:3018)
at java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:489)
at sun.net.www.protocol.https.HttpsURLConnectionImpl.getResponseCode(HttpsURLConnectionImpl.java:338)
at foo.bar.proj.OozieWorkflowTest.executeRequest(OozieWorkflowTest.java:193)
at foo.bar.proj.OozieWorkflowTest.testWorkflowOverRestApi(OozieWorkflowTest.java:120)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at junit.framework.TestCase.runTest(TestCase.java:176)
at junit.framework.TestCase.runBare(TestCase.java:141)
at junit.framework.TestResult$1.protect(TestResult.java:122)
at junit.framework.TestResult.runProtected(TestResult.java:142)
at junit.framework.TestResult.run(TestResult.java:125)
at junit.framework.TestCase.run(TestCase.java:129)
at junit.framework.TestSuite.runTest(TestSuite.java:252)
at junit.framework.TestSuite.run(TestSuite.java:247)
at org.junit.internal.runners.JUnit38ClassRunner.run(JUnit38ClassRunner.java:86)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
at org.junit.vintage.engine.execution.RunnerExecutor.execute(RunnerExecutor.java:42)
at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:184)
at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193)
at java.util.Iterator.forEachRemaining(Iterator.java:116)
at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801)
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151)
at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174)
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:418)
at org.junit.vintage.engine.VintageTestEngine.executeAllChildren(VintageTestEngine.java:83)
at org.junit.vintage.engine.VintageTestEngine.execute(VintageTestEngine.java:74)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:170)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:154)
at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:90)
at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:74)
at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
Caused by: java.lang.NullPointerException
at java.util.Base64$Encoder.encode(Base64.java:261)
at java.util.Base64$Encoder.encodeToString(Base64.java:315)
at sun.net.www.protocol.http.NegotiateAuthentication.setHeaders(NegotiateAuthentication.java:182)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1731)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1474)
at java.net.HttpURLConnection.getResponseCode(HttpURLConnection.java:480)
... 38 more
该错误是由于与请求一起发送的XML文件中的一些语法错误，因此无法正确处理整个请求。但是，curl请求返回至少400，而Java根本没有得到任何响应。我创建了一个错误报告，但是没有太大的机会，因为API是私有的，否则很难再现这种行为。