[英]Unable to connect with MongoDB using Java Driver on Heroku
I am building a web application with Java and MongoDB on Heroku. 我正在Heroku上使用Java和MongoDB构建Web应用程序。 I learnt this project from here .
我从这里学到了这个项目。 I have been kept trying for two days.
我一直努力尝试了两天。
I use 3.2.2 mongo-java-driver
and 3.5.1 maven-compiler-plugin
我使用
3.2.2 mongo-java-driver
和3.5.1 maven-compiler-plugin
This is in my Main
class: 这是在我的
Main
班上:
public static void main(String[] args) throws MongoException, UnknownHostException, Exception {
MongoClientURI uri = new MongoClientURI(System.getenv("MONGOHQ_URL"));
MongoClient mongoClient = new MongoClient(uri);
String dbname = uri.getDatabase();
//mongoClient.setWriteConcern(WriteConcern.JOURNALED);
DB db = mongoClient.getDB(dbname);
staticFileLocation("/public");
new TodoResource(new TodoService(db));
MongoCredential credential = MongoCredential.createCredential(uri.getUsername(),dbname,uri.getPassword());
MongoClientOptions mongoClientOptions = MongoClientOptions.builder().build();
}
And I got this error: 我得到了这个错误:
1:38:42 AM web.1 | Exception in thread "main"
1:38:42 AM web.1 | java.lang.NullPointerException
1:38:42 AM web.1 | at com.mongodb.MongoClientURI.<init> (MongoClientURI.java:174…
1:38:42 AM web.1 | at com.mongodb.MongoClientURI.<init> (MongoClientURI.java:159…
1:38:42 AM web.1 | at Main.main(Main.java:32)
It's NullPointerException, so I tried to replace MONGOHQ_URL
by mongodb://user:passwd@host1:port1,host2:port2/dbname
, and I also tried to use mLab MongoDB on Heroku, but the same error: 它是NullPointerException,因此我尝试用
mongodb://user:passwd@host1:port1,host2:port2/dbname
替换MONGOHQ_URL
,并且我还尝试在Heroku上使用mLab MongoDB ,但存在相同的错误:
11:17:05 AM web.1 | SLF4J: Class path contains multiple SLF4J bindings.
11:17:05 AM web.1 | SLF4J: Found binding in [jar:file:/Users/zhugejunwei/full-sta…
11:17:05 AM web.1 | SLF4J: Found binding in [jar:file:/Users/zhugejunwei/full-sta…
11:17:05 AM web.1 | SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings …
11:17:05 AM web.1 | SLF4J: Actual binding is of type [org.slf4j.impl.Log4jLoggerF…
11:17:05 AM web.1 | Exception in thread "main" java.lang.NullPointerException
11:17:05 AM web.1 | at com.mongodb.ConnectionString.<init>(ConnectionString.java…
11:17:05 AM web.1 | at com.mongodb.MongoClientURI.<init>(MongoClientURI.java:176…
11:17:05 AM web.1 | at com.mongodb.MongoClientURI.<init>(MongoClientURI.java:158…
11:17:05 AM web.1 | at Main.main(Main.java:28)
From the original version to my current version, I really tried a lot, and I just want to make it runnable on Heroku to learn this project in another way. 从原始版本到当前版本,我确实做了很多尝试,并且我只想使其在Heroku上可运行以通过另一种方式学习此项目。
When I learnt another tutorial, the code below is ok, but I don't know why it doesn't work in this project. 当我学习了另一个教程时,下面的代码还可以,但是我不知道为什么它在该项目中不起作用。
MongoURI mongoURI = new MongoURI(System.getenv("MONGOHQ_URL"));
//get connected
DB db = mongoURI.connectDB();
mongoURI.getPassword());
MongoCredential credential = MongoCredential.createCredential(mongoURI.getUsername(), mongoURI.getDatabase(), mongoURI.getPassword());
MongoClient mongoClient = new MongoClient(new ServerAddress(), Arrays.asList(credential));
I also opened an issue on github and on jira 我还在github和jira上打开了一个问题
Please help me with this issue. 请帮我解决这个问题。 Thanks in advance.
提前致谢。
I tried for more than 40 hours, and finally get it worked. 我尝试了40多个小时,终于成功了。
I changed a lot. 我改变了很多。 Here are something I think is important:
我认为这很重要:
First, it seems I cannot use DB db = mongoURI.connectDB();
首先,看来我不能使用
DB db = mongoURI.connectDB();
, maybe because of the 3.2.2 java-driver version or because of the MongoDB version on Heroku. ,可能是因为3.2.2 java驱动程序版本,还是因为Heroku上的MongoDB版本 。 When I use "
MongoDatabase
" instead of " DB
", some errors disappeared, but still cannot run the project. 当我使用“
MongoDatabase
”代替“ DB
”时, 一些错误消失了,但仍然无法运行项目。 Because I have to changed a lot in my project wherever used "DB", and this is very difficult to change from DB
to MongoDatabase
. 因为无论在哪里使用“ DB”,我都必须在项目中进行很多更改,而从
DB
更改为MongoDatabase
。
I realized that I can use DB
in 2.7.2 , so I changed all the syntaxes related to the mongo-java-driver version. 我意识到可以在2.7.2中使用
DB
,因此我更改了与mongo-java-driver版本有关的所有语法。 But again, errors disappeared, I cannot run the project. 但是同样,错误消失了,我无法运行该项目。 However, at this time, it seems most errors disappeared.
但是,这时似乎大多数错误都消失了。 One more error showed that another process is running on the same port.
另一个错误表明另一个进程正在同一端口上运行。 I killed that process.
我杀死了那个过程。 Now all errors gone.
现在所有错误都消失了。 When I run it, I cannot open it on Heroku, but on port 4567. This is weird, because the default port for Heroku is 5000, and 4567 is the default port for Jetty, which is a embedded server for Java application.
当我运行它时,无法在Heroku上打开它,而无法在端口4567上打开它。这很奇怪,因为Heroku的默认端口为5000,而4567是Jetty的默认端口,Jetty是Java应用程序的嵌入式服务器。 I added this piece of code, and it finally worked.
我添加了这段代码,终于奏效了。
port(Integer.valueOf(System.getenv("PORT")));
Thanks to my professor and thanks to all the people that helped me. 感谢我的教授,也感谢所有帮助我的人。
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