添加suggested行：
CountDownLatch latch = new CountDownLatch(1);
..
latch.countDown();
latch.await();
在Netbeans的ant jar之后公开了以下异常：
-do-jar:
jar:
BUILD SUCCESSFUL
Total time: 2 seconds
thufir@doge:~/NetBeansProjects/Firebase$
thufir@doge:~/NetBeansProjects/Firebase$ java -jar dist/
Firebase.jar lib/
thufir@doge:~/NetBeansProjects/Firebase$ java -jar dist/Firebase.jar
Exception in thread "pool-4-thread-1" java.lang.NoClassDefFoundError: com/google/api/client/auth/oauth2/Credential
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at com.google.firebase.auth.FirebaseCredentials$CertCredential.fetchCredential(FirebaseCredentials.java:276)
at com.google.firebase.auth.FirebaseCredentials$BaseCredential$1.call(FirebaseCredentials.java:229)
at com.google.firebase.auth.FirebaseCredentials$BaseCredential$1.call(FirebaseCredentials.java:224)
at com.google.firebase.tasks.Tasks$1.run(Tasks.java:78)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.ClassNotFoundException: com.google.api.client.auth.oauth2.Credential
at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 19 more
^Cthufir@doge:~/NetBeansProjects/Firebase$
thufir@doge:~/NetBeansProjects/Firebase$
thufir@doge:~/NetBeansProjects/Firebase$ ll dist/lib/
total 5024
drwxrwxr-x 2 thufir thufir 4096 Jul 3 20:19 ./
drwxrwxr-x 3 thufir thufir 4096 Jul 3 20:18 ../
-rw-rw-r-- 1 thufir thufir 648491 Jul 3 20:19 firebase-admin-5.2.0.jar
-rw-rw-r-- 1 thufir thufir 430683 Jul 3 20:19 firebase-client-jvm-2.2.3.jar
-rw-rw-r-- 1 thufir thufir 610019 Jul 3 20:19 firebase-server-sdk-3.0.3.jar
-rw-rw-r-- 1 thufir thufir 199100 Jul 3 20:19 google-api-client-1.22.0.jar
-rw-rw-r-- 1 thufir thufir 239194 Jul 3 20:19 google-api-client-1.4.1-beta.jar
-rw-rw-r-- 1 thufir thufir 16799 Jul 3 20:19 google-api-client-auth-oauth2-1.2.3-alpha.jar
-rw-rw-r-- 1 thufir thufir 6720 Jul 3 20:19 google-http-client-jackson2-1.22.0.jar
-rw-rw-r-- 1 thufir thufir 2575022 Jul 3 20:19 guava-22.0.jar
-rw-rw-r-- 1 thufir thufir 316575 Jul 3 20:19 jackson-core-2.9.0.pr4.jar
-rw-rw-r-- 1 thufir thufir 15896 Jul 3 20:19 jackson-jaxrs-json-provider-2.9.0.pr4.jar
-rw-rw-r-- 1 thufir thufir 57264 Jul 3 20:19 json-20170516.jar
thufir@doge:~/NetBeansProjects/Firebase$
代码：
package dur.bounceme.net.firebase;
import com.google.firebase.FirebaseApp;
import com.google.firebase.FirebaseOptions;
import com.google.firebase.auth.FirebaseCredentials;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.List;
import java.util.Properties;
import java.util.concurrent.CountDownLatch;
import java.util.logging.Level;
import java.util.logging.Logger;
public class FirebaseQuery {
private static final Logger log = Logger.getLogger(FirebaseQuery.class.getName());
private DatabaseReference databaseReference = null;
private Properties firebaseProperties = null;
public FirebaseQuery() {
}
void setProperties(Properties firebaseProperties) {
this.firebaseProperties = firebaseProperties;
}
void pushUsers(List<User> users) {
for (User u : users) {
databaseReference.child("users").child(u.uuid.toString()).setValue(u);
}
}
void tryQuery() {
try {
query();
} catch (IOException ex) {
Logger.getLogger(FirebaseQuery.class.getName()).log(Level.SEVERE, null, ex);
} catch (InterruptedException ex) {
Logger.getLogger(FirebaseQuery.class.getName()).log(Level.SEVERE, null, ex);
}
}
private void query() throws FileNotFoundException, IOException, InterruptedException {
String url = firebaseProperties.getProperty("url");
FileInputStream serviceAccount = new FileInputStream("serviceAccountKey.json");
FirebaseOptions options = new FirebaseOptions.Builder()
.setCredential(FirebaseCredentials.fromCertificate(serviceAccount))
.setDatabaseUrl(url)
.build();
FirebaseApp firebaseApp = FirebaseApp.initializeApp(options);
FirebaseDatabase firebaseDatabase = FirebaseDatabase.getInstance(firebaseApp, url);
databaseReference = firebaseDatabase.getReference().getRoot();
CountDownLatch latch = new CountDownLatch(1);
databaseReference.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
String key = null;
String value = null;
for (DataSnapshot childSnapshot : dataSnapshot.getChildren()) {
key = childSnapshot.getKey();
value = (String) childSnapshot.getValue();
log.info(key + "\t\t" + value);
}
latch.countDown();
}
@Override
public void onCancelled(DatabaseError databaseError) {
latch.countDown();
throw databaseError.toException();
}
});
latch.await();
}
}
据我所知，这些是correct个套餐，但显然不是因为没有Credential类：
thufir@doge:~/NetBeansProjects/Firebase$
thufir@doge:~/NetBeansProjects/Firebase$ jar -tf dist/lib/google-api-client-auth-oauth2-1.2.3-alpha.jar
META-INF/
META-INF/MANIFEST.MF
com/
com/google/
com/google/api/
com/google/api/client/
com/google/api/client/auth/
com/google/api/client/auth/oauth2/
com/google/api/client/auth/oauth2/AccessProtectedResource$AccessTokenIntercepter.class
com/google/api/client/auth/oauth2/AccessProtectedResource$UsingAuthorizationHeader.class
com/google/api/client/auth/oauth2/AccessProtectedResource$UsingQueryParameter.class
com/google/api/client/auth/oauth2/AccessProtectedResource$UsingFormEncodedBody.class
com/google/api/client/auth/oauth2/AccessProtectedResource.class
com/google/api/client/auth/oauth2/AccessTokenRequest$AuthorizationCodeGrant.class
com/google/api/client/auth/oauth2/AccessTokenRequest$ResourceOwnerPasswordCredentialsGrant.class
com/google/api/client/auth/oauth2/AccessTokenRequest$AssertionGrant.class
com/google/api/client/auth/oauth2/AccessTokenRequest$RefreshTokenGrant.class
com/google/api/client/auth/oauth2/AccessTokenRequest.class
com/google/api/client/auth/oauth2/AccessTokenErrorResponse$KnownError.class
com/google/api/client/auth/oauth2/AccessTokenErrorResponse.class
com/google/api/client/auth/oauth2/AccessTokenResponse.class
com/google/api/client/auth/oauth2/AuthorizationRequestUrl$ResponseType.class
com/google/api/client/auth/oauth2/AuthorizationRequestUrl.class
com/google/api/client/auth/oauth2/AuthorizationResponse$KnownError.class
com/google/api/client/auth/oauth2/AuthorizationResponse.class
META-INF/maven/
META-INF/maven/com.google.api.client/
META-INF/maven/com.google.api.client/google-api-client-auth-oauth2/
META-INF/maven/com.google.api.client/google-api-client-auth-oauth2/pom.xml
META-INF/maven/com.google.api.client/google-api-client-auth-oauth2/pom.properties
thufir@doge:~/NetBeansProjects/Firebase$
我在哪里可以下载这个特定类的JAR？无论是从CLI通过ant run运行，如上所述直接运行JAR，还是使用Netbeans，都会发生异常。