java - 如何检查是否与 Java 建立了 MongoDB 连接？

Question

在我的应用程序中，MongoDB 3.2.4 在自定义端口上运行，我想实现我的应用程序将尝试在自定义端口上访问 MongoDB 的逻辑，如果失败，它将使用默认的 27018 端口。

为此，我使用了以下代码:

String mongoClientURI = "mongodb://" + DB_SRV_USR + ":" + DB_SRV_PWD + "@" + DB_URL + ":" + DB_PORT_CUS + "/" + dbName;
MongoClientURI connectionString = new MongoClientURI(mongoClientURI);

// enable SSL connection
MongoClientOptions.builder().sslEnabled(true).build();

if (this.mongoClient == null) {
    this.mongoClient = new MongoClient(connectionString);
}

// create database if doesn't exist
MongoDatabase mdb = this.mongoClient.getDatabase(dbName);

try {
    this.mongoClient.getAddress();
} catch (com.mongodb.MongoSocketOpenException e) {
    System.out.println("Switch to default port");
    /*…use default port logic…*/
}

问题是没有捕获到这个异常。 尽管 MongoDB 抛出以下异常:

com.mongodb.MongoSocketOpenException: Exception opening socket at com.mongodb.connection.SocketStream.open(SocketStream.java:63) at com.mongodb.connection.InternalStreamConnection.open(InternalStreamConnection.java:114) at com.mongodb.connection.DefaultServerMonitor$ServerMonitorRunnable.run(DefaultServerMonitor.java:128) at java.lang.Thread.run(Thread.java:745) Caused by: java.net.ConnectException: Connection refused: connect at java.net.DualStackPlainSocketImpl.waitForConnect(Native Method) at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:85) at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350) at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) 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 com.mongodb.connection.SocketStreamHelper.initialize(SocketStreamHelper.java:50) at com.mongodb.connection.SocketStream.open(SocketStream.java:58) ... 3 more

我的 try-catch 表达式无法捕获此异常。

我尝试了多种方法，比如捕捉:

• 异常
• 运行时异常
• MongoSocketOpenException
• MongoException
• MongoCommandException

它们都不起作用。

我的问题:

1. 如何检查 MongoDB 连接是否建立？

2. 如何捕获异常MongoSocketOpenException？

Answer 1

1. 我使用这段代码来检查连接:

   try {
       mongo.getAddress();
   } catch (Exception e) {
       System.out.println("Database unavailable!");
       mongo.close();
       return;
   }
   

2. 不确定我的猜测是 this.mongoClient.getAddress(); 不会抛出该异常，但我真的不知道

编辑:我通过以下方式初始化它:

Builder builder = MongoClientOptions.builder().connectTimeout(3000);  
MongoClient mongo = new MongoClient(new ServerAddress("192.168.0.1", 3000), builder.build());